Intro Object Making

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Introduction to Object Making

GDL for Beginners

Written by David Nicholson-Cole


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Graphisoft Visit the Graphisoft website at http://www.graphisoft.com for local distributor and product availability information.

Introduction to Object Making© 2004. Originally written 2000, rewritten 2004 by David Nicholson-Cole. All rights reserved. Reproduction, paraphrasing or translation without express prior written permission of Graphisoft is strictly prohibited.

Cover credits: Marks Barfield Architects, creators of the British Airways London Eye, http://www.marksbarfield.com. GDL model by DavidNicholson-Cole.

Published by GRAPHISOFT R&D Rt.

2004 edition.

The version of GDL described in this manual is compatible with ArchiCAD 8.1, ArchiCAD 9 and ArchiFM 2000.

Trademarks ArchiCAD and ArchiFM are registered trademarks and PlotMaker, Virtual Building, StairMaker and GDL are trademarks of Graphisoft. IFC

and IAI are trademarks of the International Alliance for Interoperability. Artlantis and PhotoCAD are trademarks of Abvent. Piranesi is atrademark of Informatix. ArchiFacade is a trademark of Cigraph. Lara Croft is a trademark of Core Design. Lightworks is the trademark ofLightwork Design. All other trademarks are the property of their respective holders.

http://www.graphisoft.com/http://www.graphisoft.com/


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3 IIntroduction to Object Making

About this Book

Introduction to Object Making is designed to help you get moreenjoyment and productivity from ArchiCAD: it takes you beyond theconfines of the standard ArchiCAD Tool palette into the realm ofobject making. We hope that this little primer will open up new

worlds for each user. Part I, Object Making Without GDL, shows youhow to make objects using existing tools, without having to touch anyGDL script. Part II, Beginners’ Guide to GDL Scripting, eases youinto the possibilities of GDL scripting. We hope you will find thetransition enjoyable, but please note that you don’t have to read the whole book to get useful information: even if you never get to theGDL script, the initial object-making tips will greatly enhance yourconfidence and productivity with ArchiCAD.

Some of the examples used in the book will be available from thesupport website or from the installer CD.

About the Author

David Nicholson-Cole is an architect and teaches at NottinghamUniversity in the UK. He has been an enthusiastic evangelist forGDL and a prodigious producer of GDL objects since discoveringthe power (and the pleasure) of GDL.

He made his mark in the GDL world as the author of the series ofGDL training books, the GDL Cookbook. David founded the‘ArchiCAD University’ series of user conferences, and is a foundermember of the GDL Alliance.

The GDL Cookbook 4 logically follows after the book you are nowreading. It is an A-Z of GDL technique, and is usable in its own rightas a GDL manual. David has also travelled around the Globe at theinvitation of ArchiCAD dealers and their customers, teaching GDL.

Acknowledgements

Introduction to Object Making with ArchiCAD: GDL for Beginners wasdeveloped in concept by Graphisoft as a means of filling the gapbetween the GDL Cookbook and the existing reference manuals. Thefirst edition was in 2000 for ArchiCAD 6.5 and 7.0.

This edition has been completely rewritten during 2004 to include ArchiCAD 8 and ArchiCAD 9 thinking and techniques. It containseasy to follow exercises in object making, and pulls together wisdom

about object making from other sources, including the referencemanuals, for which all the authoring team should be thanked. It takesobject making a lot further than the original volume.

The author would like to thank his editing team at Graphisoft - AnettCsaki, Tibor Szolnaki and Akos Pfemeter - for their regular emails of

advice and support. He would also like to thank Karl Ottenstein ofSandpoint, Idaho for his critiques and technical proofreading duringthe writing.

Printing Note

We have provided this as a .PDF file, but we have designed it with

chapters starting on odd numbered pages. This is to enable you toprint out your own copy and run it off on a double sided photocopier

if you wish to save paper.


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4 IIntroduction to Object Making


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Introduction to Object Making 5

CONTENTSPART ONE: OBJECT MAKING WITHOUT GDL______________ 9Chapter 1: Introduction to Object Making. . . . . . . . . . . . . . . . . . . . . . .9

1.1 About Object Making . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9Library Parts in ArchiCAD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10Sources of Library Parts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13

Add-ons that make Objects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .141.2 Making your own Library Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Without GDL – using ArchiCAD’s Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . .14 Making Objects with GDL Scripts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15 How do you make an Object? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16 Does it need to LOOK right, or BE right? . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16 The idea of an ‘Investment Object’ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Can you learn GDL?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17 The ArchiCAD experience . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17 Read about Object Making . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18

Chapter 2: Object Making without GDL 1 . . . . . . . . . . . . . . . . . . . . . . 192.1 Making Objects without GDL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19Getting started with Object Making . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19

2.2 Let’s make something in 2D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 202.3 Bring a file in from DXF/DWG. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .202.4 Let’s make a 3D Object – a Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 212.5 Let’s Make a 3D Window with slabs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 222.6 Let’s make a Chair using Wall tool. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .242.7 Let’s make a Roof Truss with Fills . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Summary of Object Making in this chapter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 Chapter 3: Object Making without GDL 2 . . . . . . . . . . . . . . . . . . . . . .283.1 Using Basic Shapes from the Library . . . . . . . . . . . . . . . . . . . . . . . . . . . .28

Make a ‘Banana’ Truss or Mullion object. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28 3.2 Let’s make an Object by Cutting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 293.3 Urban Modelling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Urban modelling – entire buildings as objects. . . . . . . . . . . . . . . . . . . . . . . . . . . .32 Urban modelling – entire sites can be objects . . . . . . . . . . . . . . . . . . . . . . . . . . . .33Urban modelling – the Camera is the mightiest weapon! . . . . . . . . . . . . . . . . . . . .33

3.4 Making Objects with Add-ons and Solid Geometry . . . . . . . . . . . . . . . . 33Profiler – for extrusions and lathing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

3.5 Make a Flywheel with Profiler! . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .353.6 Convert Mesh to Roof . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .37

Other free Add-ons within ArchiCAD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 3.7 Carving Walls with the Roof tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .38

Solid Element Operations (SEO) to the rescue! . . . . . . . . . . . . . . . . . . . . . . . . . .39

Notes on the naming of parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .40Why bother to make objects? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .40 Are you using the Student version? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .41Summary of Object Making in this chapter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

PART TWO: BEGINNERS' GUIDE TO GDL SCRIPTING _____ 42Chapter 4: Starting with GDL. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

4.1 Starting with GDL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .42The Scripts and Buttons in the Parameter Table. . . . . . . . . . . . . . . . . . . . . . . . . .42 3D Entities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .44First steps in 3D GDL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .443D View. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .44Check Script . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .45 3D Space and the 3D Cursor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .45 Do not forget the 2D script . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .46 Summary of GDL, to this point. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .46

4.2 Let’s build a 3D Object – a Chair . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .474.3 Let’s make this chair parametric. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .484.4 First steps in 2D scripting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .50

Selecting Objects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .52

Subtypes – you can put this into a category. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .52 Summary of GDL, in this chapter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .52 Chapter 5: Providing Options in GDL . . . . . . . . . . . . . . . . . . . . . . . . . 545.1 Providing Options in GDL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .545.2 Boolean parameters – easy options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .545.3 Popdown Menus: allow many choices. . . . . . . . . . . . . . . . . . . . . . . . . . . .565.4 The MultiObject concept . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .58

Summary of GDL in this chapter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .61Chapter 6: The Power of PRISM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 626.1 The Power of PRISM. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .62

PRISM is the most versatile element in 3D GDL . . . . . . . . . . . . . . . . . . . . . . . .62 ‘Instant GDL’. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .63Writing Prisms from new. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .64

About Prism syntax.... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .646.2 Apply Prisms to the chair seatframe . . . . . . . . . . . . . . . . . . . . . . . . . . . . .666.3 Learn about Circle Geometry and make the chair more comfortable. . .68

Summary of GDL in this section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .70Chapter 7: Looking into Autoscripted GDL . . . . . . . . . . . . . . . . . . . . 717.1 Looking into Autoscripted GDL. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .71

Examine the 3D script of the autoscripted table . . . . . . . . . . . . . . . . . . . . . . . . . .71The table can be tuned up – to be parametric . . . . . . . . . . . . . . . . . . . . . . . . . . . .74Cautionary note for modifying objects. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .79

7.2 Come back to ‘Instant GDL’ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .79Try instant GDL with a REVOLVE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .80

Modifying objects made with Add-ons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .82

Summary of GDL in this section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .82 Chapter 8: Build on the power of GDL . . . . . . . . . . . . . . . . . . . . . . . . 838.1 Subroutines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .83

Golden Rules for Subroutines. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .84

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Contents

6 Introduction to Object Making

8.2 Macros . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85Subroutines versus Macros . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85 Complex example of Macros . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86

8.3 Textures – the big secret revealed. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87You could do Texture mapping with a Macro . . . . . . . . . . . . . . . . . . . . . . . . . . . 89

More things to note on textures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89 Summary of GDL in this se ction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90

Chapter 9: Billboard Objects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 919.1 Billboard Objects – use picturereality! . . . . . . . . . . . . . . . . . . . . . . . . . . . 919.2 Make your own Billboards as accurate Cutouts . . . . . . . . . . . . . . . . . . . . 929.3 Make your own Billboards using the Alpha Channel with PICTURE . . 959.4 Rectangular ‘cutout’ – the combination object . . . . . . . . . . . . . . . . . . . . 979.5 The Billboard idea in 2D?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 989.6 Billboard creation – the photograph . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99

Summary of Billboarding in this section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100Chapter 10: GDL Windows and Doors. . . . . . . . . . . . . . . . . . . . . . . . 10110.1 GDL Windows and Doors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101

The Rules of Windows and Doors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10110.2 Revisit the Window . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102

10.3 You can make Skylights too . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10510.4 Try a very complex window!. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107 Note for future versions of ArchiCAD. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110

Objects can be better than Windows . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110Summary of GDL covered in this chapter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110

Chapter 11: GDL Roundup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11211.1 GDL Roundup. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112

The programming language of GDL. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112 11.2 Loops – FOR... NEXT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113

The FOR... NEXT Loop . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113Loop by counting numbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113Loop by Distance – and optimise it! . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114Smart way to recalculate spacing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114Loop by Angle. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115 Other ways of Looping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116

11.3 Graphical Hotspots . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117Let’s write some Graphical Hotspots . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118

11.4 Solid Geometry Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118Solid Geometry on the chair. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119

11.5 Defining Text in 2D. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12011.6 Other possibilities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12111.7 Advice for Newcomers to GDL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12111.8 Summary of ArchiCAD 9 changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122

Index ___________________________________________________123


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PART ONE: OBJECT MAKING WITHOUT GDL

CHAPTER 1: INTRODUCTION TO OBJECT M AKING

An introduction to the possibilities of object making in ArchiCAD, with or without GDL. Architecture is... “the conscious, correct, and magnificent interplay of volumes assembled under light”. -- Le Corbusier

1.1 About Object Making

The real 3D world can be thought of as a vast assembly of objectsmade visible in light. ArchiCAD’s 3D environment can be thought ofas a large theatrical stage where you assemble the cast (the elementsand objects), the set (the plan) and the screenplay (the design idea). You bring the objects together, illuminate them, and then – let the

play begin!Most of the objects in the ArchiCAD assembly area are buildingelements – walls, slabs, roofs, columns, meshes, etc. – broughttogether to form buildings. These elements are easily made with thetools given to you in ArchiCAD.

Whenever you need to go beyond walls and floors, you can use specialobjects such as furniture, windows and doors, lamps and components.In ArchiCAD manuals, these are also referred to extensively as LibraryParts. These can be found in your library or made specially. So, whyshould we bother to make objects? Well, we can make:

• Structural elements that are right for their purpose.• Details of building construction that look authentic.

• Furniture that is smart, functional and elegant.

• Components that conform to catalog numbers and manufacturers’specifications.

• Lamps that can transform the environment of a model.

• Windows, Doors that cut holes in walls, open or swivel, offer achoice of styles for frames, ironwork and leaves or sashes.

• Skylights and Dormers that cut holes in roofs like windows cut

holes in walls.• Label tools or blocks of custom text.

• Stairs in which you can vary landings, risers and handrails.

• Picture objects that can be placed in a model to look like people,trees, or even whole buildings.

• 2D drawing objects and tools that can enhance your productivityand drawing accuracy.

In short, the pleasure and productivity of the ArchiCAD user can begreatly enhanced with objects. This book is intended to ease the ArchiCAD user safely into making objects. It is not entirely self

contained; it needs to be read with the GDL Reference Manual, theHelp Menu and the main ArchiCAD Reference Guide. Dip into thesefrequently. If you wish to take object making further, your next stagesafter this primer are to take a more informed look at the manual andGDL Help menu, and to work with the GDL Cookbook, all of whichtake you progressively into more advanced GDL.


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The Eureka Tower in Melbourne, Australia, by Fender Katsalidis: ObjectTechnology is not just for pretty renderings – it is central to the task ofconstruction documentation.

Library Parts in ArchiCAD

When you build an ArchiCAD project, you can use the primarymodelling tools – walls, slabs, columns, roofs, etc. The ArchiCAD

Tools palette also offers access to library parts: furniture objects,lamps, windows, doors, skylights etc. In the Tools palette or the Toolsmenu or Extras menu, you may also find add-ons such as ArchiTerra,StairMaker, Profiler or RoofMaker. To place an object in the projectyou can use different actions, such as click and stretch, click and clickagain to indicate direction, or you may encounter an entire dialog boxcontaining instructions and many data fields

In your use of ArchiCAD, you will have noticed that most libraryparts offer many chances for variation (called parameters) such as thenumber of mullions in a window or glazing styles in a door. They may

also offer different ways (in materials, pens and fills) of representingthemselves in the 3D view and in 2D.

If you have tried making objects in ArchiCAD without GDL (we willcall these ‘Autoscripted’ objects), you are used to getting an object whose only possibility for variation is stretchiness. You are notoffered a choice of materials, you have to get these right before savingthe object. This introduction to object making will encourage you tobuild objects yourself, but more significantly it will encourage you totry to make them capable of offering variations – thus they could bepartially parametric.

Libraries must be loaded

Whatever you make, however you make it, ArchiCAD must be able tofind the object. Every time you open ArchiCAD, it reads through thelibrary directories (folders) and makes an index of what it finds.

The existing ArchiCAD Library is a folder in your installed ArchiCAD directory. ArchiCAD’s own library will be loaded (bydefault) but when you are running a project, or experimenting withGDL, you should make additional folders of your objects. Make sureyou do not make objects or folders with the same names as ones that

already exist in the libraries. When you are working with ArchiCAD,make sure that the folder you are saving your objects to is one of yourloaded libraries.


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You can either make a new library folder that relates to currentprojects, or your objects can be stored in a personal library in the ArchiCAD folder. The main point is that you should know wherethey are, and ensure that you have loaded them. Subfolders to keepfurniture objects, building components, window objects, textures etc.,should be logically named and organized.

What’s new since the last object making book?

There are many small changes in the GDL since the year 2000, butlet’s look at the four most notable changes that affect the objectmaker.

Subtypes: All object names now end with a .GSM, and they carry aunique internal ID number which enables ArchiCAD to know if theyare windows, doors, lamps etc. International conferences have agreedon a way of classifying objects in the virtual world called IndustryFoundation Classes (IFCs). Graphisoft play a leading part in thismovement. A 3D model is in reality a vast database, of which the 3Dform is a visible manifestation, and the design process is just onestage in the life of the building. The IFC concept considers thelifecycle stages of conception, design, management and even

demolition of the built environment. Documentation is vital at everystage and buildings have to be managed by teams of people whorequire access to shared information databases.

Objects in the environment can be classified by Subtype – forexample they will be Seating, Windows, Roof structure, Storage or

other similar categories. If your ArchiCAD model uses internationallysourced GDL components, how does it know the difference betweenobjects called ‘sedia’, ‘janela’, ‘fenster’, ‘Tür’, ‘tepe_penceresi’,‘iskemle’, ‘parathiro’? Is a ‘lanterna’ a lamp or a skylight? ArchiCADknows!

All objects now have an internal identity code GUID ( GloballyUnique IDentifier) which includes the subtype classification, andenables the APIs inside ArchiCAD to perform correctly whatever theobject’s name – so a skylight will cut a hole in a roof but not a wall; alamp will have brightness and colour controls but cannot cut holes ina roof.

The GUID is very powerful – more so than the object’s name. As a

risky experiment, I changed the name of an object in a library,reloaded libraries and checked the plan. The object was still in the


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correct place, with its new name, and looked the same in 3D view –because the GUID was unchanged (don’t do this at home!).

You can see a quick sample of the IFC categories in GDL by going toFile>GDL Objects>Open Object by Subtype – click open thecascading groups and you will get a comprehensive listing of the

possibilities – even animals, cars and railings are included.Graphical Hotspots (GHs): GDL objects can now have customhotspots in any part of the model for editing its configuration.Previous versions of GDL only permitted stretching of an imaginarycuboid around the object. Now an object of some complexity can bemanipulated by the user – in a piece of storage furniture, you can pullor push the drawers, swing open or shut the doors, change thespacing of shelves or dividers – it is easy to do using hotspots in the3D or the 2D or both, and the hotspot coding is not difficult. For theGDL writer, GHs are very rewarding to write and get working.

This structural steel tube can be stretched and twisted and rotated – in 3D space

and in 2D using graphical hotspots.Solid Geometry Commands (SGC): We can achieve a far moreauthentic 3D appearance and improved line drawing of objects byadding or subtracting solids. Where intersecting tubes would lookacceptable in 3D render but wrong in wireframe, we can now addthem and get cleancut junctions. We can now subtract 3D outlinesout of a 3D solid surface (for example spherical indents into a slab) tocreate shapes that could not be built with ‘positive’ constructioncommands. These are similar to the Solid Element Operations in ArchiCAD.

This carved wood arch is now easy with SGC.

Open GL: This is a new engine for fast 3D visualisation, originallydevised by Silicon Graphics. It is much faster than ArchiCAD’s 3Dengine, using accelerated routines on dedicated hardware – thegraphics card of your computer, Mac or PC. Open GL includesroutines for hidden line, shading, texture mapping, texture filtering,anti-aliasing, lighting, geometry transformations, etc. This affects youbecause previously, textures were relatively unconsidered. Now itlooks blatantly horrid if you are lazy with textures and all your woodgrain goes the wrong way. It can also cope with models of morepolygons allowing a higher level of detail, more curviness. Open GLdrawings can be preferred to renderings as they include pen lines, asin most of the illustrations in this book.

Rendering: ArchiCAD 9 introduces the major advance in renderingtechnology, Lightworks. It is one of the most popular renderingengines available on the market. Currently more then 80 applicationsare licensing this technology and a total of 1 million end users areusing it.

The Lightworks rendering engine is now built into the ArchiCADrendering interface. Lightworks gives you the ability to create highquality photorealistic images within ArchiCAD. Lightworks offersray-tracing, soft shadow and reflection features and complex shaderediting capabilities, and works with ArchiCAD’s own elements.

Find more details in the ArchiCAD 9 documentation, and see the website: http://www.lightworks.com/.

Future developments with ArchiCAD

Whichever version you are using by the time you read this, you can be

sure that it will be easy to find your way around. Every new releasehas been safely incremental, so that users have been able to adapt


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readily to new capabilities. The fundamental modelling tools (Walls,Slabs, Roofs) have changed for the better, but are still familar witheach new release. We have an extra armoury of tools like the Column,Beam and Mesh, the continuous Line tool – and in recent times, wehave the technology of ‘Add-ons’ – custom tools which makemodelling even easier. GDL itself, the internal code of ArchiCAD,has also changed over the versions, but never so differently that anexperienced user couldn’t immediately make use of it, and later adaptto the new features as they became evident.

Sources of Library Parts

The ArchiCAD Library

It is worth going through the ArchiCAD Library included with yourpackage before you start creating library parts on your own.Investigate what already exists. This will give you an idea of what you

can use and do not need to make; and the examples in there will giveyou ideas of what is possible. You will be able to see how parameterschange and this will make you think about what qualities you mightlike to include in objects that you make – such as useful 3D options,clear organization and description of parameters, stretchiness withhotspots, nice textures, 3D authenticity and intelligible 2D symbols,pop down menus and even a user interface.

GDL is very widely supported – the web is ful l of sites with object making adviceand downloads.

Complementary Libraries

Several specialist libraries are available on the web or on CD fromcompanies specialising in object making and add-ons, such as Peopleand More, Theometrics, Hoshino, M.A.D., etc. If you explore the

Internet, you will find an increasing number of websites devoted to ArchiCAD objects and add-ons such as GDL Central (www.gdlcentral.com) and Objects On Line (www.objectsonline. com). Trysome of these in Google: Studio Arkada, Arkiklub, ArchiRadar, GDL Alliance, Cigraph. The Graphisoft website gives you an up-to-date listof addresses of such sites. From GDL Central, you can discover theaddresses of manufacturers using GDL for products.

You will find that, with the free GDL object web browser plug-in,GDL objects can be viewed in a browser, changed parametrically, andrendered, almost as if you were examining them from within ArchiCAD – and then perhaps, downloaded to the user.

DXF and DWG Libraries

Most building component manufacturers offer disks of DXF/DWGfiles, although most of these are 2D only. It is always worth gettingthese, as DXF/DWG files can be used in ArchiCAD, and you will be

able to make use of them in GDL. 2D DXF and DWG files can bebrought straight into the Project plan. Where you see the opportunityto make library parts out of DWG or DXF originals, you may be ableto take advantage of the parametric power available to you in GDL.

For 3D, you can also make objects with other applications from 3rdparties – Zoom, Sketchup, Rhino, Design Workshop, AutoCAD, 3DS – save them as a DXF/DWG, then bring them into ArchiCAD as alibrary part. The DXF/DWG Conversion Guide included in your ArchiCAD package explains this procedure in more detail. Sites like3D Cafe (www.3dcafe. com) are full of third party objects – although

these will be mostly DXF/DWG models requiring import into ArchiCAD via GDL. However good they may look, they will not beparametric.

You can also work in the other direction. If you take the time to learnGDL, you have the advantage over other CAD users in that you canmake a 2D or 3D library part in GDL that is parametrically variable,and you can save the resulting varied forms as separate DXF/DWGs.Parts you create in GDL will wholly or partially work in AutoCAD or ADT using the GDL Adaptor.

Using old libraries – update library parts You can use library parts from older ArchiCADs providing they have3-letter suffices. They will be much slower to load, and may work


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incorrectly. You can speed this up by opening ArchiCAD with theSpecial Menu visible. Boot up ArchiCAD holding down the Opt-Cmdkeys (Mac) or Alt-Ctrl (PC) – you will see the Special Menu appear.Load the library you want to update. Now select ‘Update Libraryparts’ from the Special Menu. It may take 10-20 mins. It is bringingthem all up to date with GUIDs and other AC8/9 characteristics.

Add-ons that make Objects

There are a number of third party programs that can create or edit ArchiCAD library parts, for example, Zoom GDL, 3NF. You will alsofind a growing number of object-making Add-ons working in ArchiCAD such as RoofMaker, Trussmaker, Profiler, Roof, Floor and Wall Accessories, ArchiForma, GDL Toolbox.

Objects created by these Add-ons contain GDL scripts as well asother, application-dependent data.

1.2 Making your own Library Parts

Without GDL – using ArchiCAD’s Tools

Walls, Slabs, Roofs and other ArchiCAD 3D tools are available in the Tools palette as custom tools for object making, regardless of theiroriginally intended purpose. You could, for example, model a diningtable easily by using walls and slabs. The legs could be tall, small slabs,or short thin walls. The tabletop could be a slab. A lipped edge to thetop could be made with a very thin low wall. The resulting structure

can be viewed in the 3D window and saved as a library part.Library parts originating from the floor plan can be saved either as‘Editable’ scripts or in ‘Binary’ format. Editable scripts give you someGDL so you can enhance the library part’s 3D appearance bymodifying its script. You can do useful work on a script, mainly inediting materials and pen values. Binary library parts offer lightningfast imaging speeds, but do not allow editing, and have no parametersother than ones enabling stretchiness – width, depth and height. Ifyou want to perform other modifications, you must return to theoriginal floor plan document, modify the model, and save it again as

the same or as another binary library part.If you save floor plan elements as a GDL script, the complexity of theresulting script will depend on the element types you have used. The

Slab tool and Roof tool will produce GDL script that is relatively easyto modify. The Wall tool creates bits of script which are harder butnot impossible to modify, but are easier to build in the first place.Some of the most interesting possibilities are with the Mesh tool, which makes surfaces that can be converted to roofs and saved asobjects.

Sometimes the objects you make with ArchiCAD tools are moreeasily built on their side, rather than upright. Windows and doorsshould be built flat on the floor and ArchiCAD will convert them tobe upright.

Sometimes you will not be able to make an object all at once. Youmay have to make the legs first and save those, then make thesuperstructure, save that, then make additional parts, and save them. There are primitives such as cylinders, cones and domes in the ArchiCAD Library that you might also use as part of your object. Youcan then bring all those subsidiary parts together in the floor plan,and save the whole result as your final library part. Later in this bookthere is an exercise to demonstrate this procedure. Be warned,though, that this final object will only work if all the subsidiaryobjects can be found in the loaded libraries.

This bentwood chair is entirely made from small walls.

For the more experienced object maker, it is possible to combine theuse of ArchiCAD tools with a knowledge of GDL. Because youcannot rotate objects in the ArchiCAD floor plan (other than aroundthe Z axis), you will quickly see the benefit of learning even a smallamount of GDL, in which you can rotate shapes however you want.

Shapes can be drawn out in the floor plan with the wall, roof or slabtool, saved as little chunks of GDL, brought back into the plan and


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then added into a larger GDL project that the writer is working on –moved and rotated into position, amended or simplified.

Not all objects need to be 3D. It is possible to use the 2D tools oflines, text and fills to draw standard symbols, select them, and‘File>GDL Object>Save selection as...’ a library part. If you alreadyhave a 3D object that you wish to use purely as 2D, you can select it,‘explode’ it, and save the resulting lines as a new 2D library part. Thisdoes not change the original 3D part.

All library parts are objects, but when you save them you can decide ifthey are to be an Object (a piece of furniture or a building component),a Window , or a Door . If it’s to be a Lamp or a special furniture object,place the object in the plan, open it and select a new Subtype for it.

This accurate ship model for the US Coastguard was built entirely by tracing overthe DWG construction drawings in ArchiCAD with 2D fills, dragging the f illshapes into GDL, and tidying up into 3D subroutines.

Assemblies built with the Tools palette do not have to be lost. Youmay want to edit or elaborate and resave. Select your assembly andsave as a Module . This will take a fraction of the disk space, and can beput in a folder near your Library with a filename that helps youremember its relation to the library object that it helped you create. With modules, you may wonder, why bother to save as objects?

The answer is, if you wish them to behave as objects (stretchy) and

allow further editing (improved materials etc.) and appear correctly inschedules, they must be saved as library parts.

Making Objects with GDL Scripts

Even a small knowledge of GDL allows you to go far beyond thepossibilities offered by the simpler methods above. If you candescribe what you want in words and numbers, you can make objects with GDL. That’s why it’s called Geometric Description

Language.• Because GDL has many 2D and 3D commands, you can make

interesting objects that cannot be made with the Tools palette –they can be Complex and Curvy.

• Because you can define diameters, spacing, thickness, materials andpens, your objects can allow variations –- they can beParametric.

• Because you specify elements in a GDL model by precisedimensions, angles or parameters, the objects will be exactly whatyou want them to be –- they can be Accurate.

• Because you can write IF statements, you can build rules ofbehavior into your objects, such as manufacturers’ requirements,checks on incorrect parameters, self-sizing components etc. – theycan be Smart..

• Because you can write routines that loop around and repeatactions many times, you can economically build large or repetitivestructures that would be futile to build with the Tools palette – your objects can be Tools.

• Because you can rotate, slide and resize components in the model,your objects can change their shape – you can makeMechanisms.

You also have the ability to decide which parts of a GDL model cancast shadows, which pen colors the object should be drawn with, howmany polygons there should be in curvy bits. You can generate yourown materials – shiny, matte, transparent or glowing – so that they will work even with an ArchiCAD in a different language from yours.GDL objects are independent of dimensional settings because theyare parametric; GDL models can animate, or contain dozens of variedconfigurations selectable from a popdown menu.

GDL is an ideal tool for the Internet, for marketing products such asoffice furniture or kitchens. GDL Objects are cross platform and


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economical in size. They can be viewed with a browser, configured intheir parameters, and downloaded.

How do you make an Object?

Look around you, examine the 3D objects that surround you as you

read this book. Observe, if you can, the essential primitive forms thatcompose each object. Most objects can be seen as composed ofblocks, prisms, cylinders, cones, tubes or surfaces. Your coffee mug isa hollowed out cylinder, with a closed bottom. Your laptop is twoflattish brick shapes hinging. Your mouse is an elongated egg shape with a flattened bottom surface. Ask yourself what detail needs to beincluded; discard detail that is not essential to the 3D render you wantto get from it – think about the viewing distance that the object willbe seen from. Use a level of detail that is within your abilities tomodel either from the Tools palette or with GDL script.

Difficult 3D tasks such as surface rippling or perforation might moreeasily be solved by using textures instead of struggling to find aphysical 3D modelling solution.

If you are using the ArchiCAD tools (not GDL), view the object interms of the familiar tools of wall, slab and roof, and include in your vision the primitive shapes from the shapes library or bits you canmake with Profiler or Trussmaker.

If using GDL, look at it in terms of blocks, spheres, cylinders andcones. As your GDL skills grow, you can add prisms, sweeps, planeand meshed surfaces and tubes.

Does it need to LOOK right, or BE right? An object that is used to furnish the interior of a house may only berequired to give a luxurious impression of the interior, an authentic‘lived in’ look. It only needs to LOOK right. This could be built with ArchiCAD’s own tools or with GDL, and the dimensions could be‘eyeballed’ – that is, you use the grid as a guide and get the size asaccurate as your eye tells you it needs to be. But using the Toolspalette, your objects will still have a ‘blocky’ look to them.

Another object may be required to be totally accurate, so that you can

derive accurately dimensioned sections and plans from it. It may needto be precise enough to fit a confined space, like a kitchen orbathroom part. At the top end, it may be required to drive a

CADCAM system (cutting tool) or a rapid prototyping machine. Soyou must be satisfied that it IS right. For this, you are better off working in GDL from the beginning.

The idea of an ‘Investment Object’

Ask yourself if the object you want to make is to be used more thanonce, if it could be useful in other projects. You might be the oneperson in the office making objects for other people, and thereforeyou need to make the object usable by others. If you make itparametric and smart, it might take you longer to make an object thatcould more quickly be made with the Tools palette. But if the objecthas versatility and can be used in many more projects, the time takento make the object well is an investment and your users will begrateful for the effort.

Investment Objects: This parapet ladder is required un-countable times on thebuildings of Orcutt Winslow (Arizona) and each one is painfully slow to draw in2D sections with differ ent heights for each ladder. The GDL object took theauthor less than an hour to write and is stretchily configurable in every conceivable

direction and provides 2D and 3D data for materials ordering and welding.


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Furthermore, objects made with the Tools palette are no longereditable if the original floor plan file that made them has been lost(and you also forgot to save them as a module!)

A piece of GDL that is well written can be extended and made morepowerful when your own knowledge of GDL improves or when anew edition of ArchiCAD offers more features. A well written objectcould be taken on by someone else in the office, years after you haveleft, and improved to take advantage of greater knowledge or of newfeatures like graphical hotspots or better texture and detail.

Here’s another investment idea – objects you make can be used in AutoCAD and ADT using the free GDL Adaptor – how manypeople may now be able to enjoy a good parametric object, andperhaps pay you for it?

Can you learn GDL?

Many objects do not need to be built with GDL – the ArchiCADtools may be enough. Experienced ArchiCAD users who are scaredof GDL get very skillful in transforming the simple 3D tools of wall,slab and roof and some add-ons into most complex objects. But they will never have the pleasure of making their objects parametric.

If you are prepared to go beyond the Tools palette, GDL is an easyscripting language compared with those available in the other CADpackages. GDL is based on BASIC, the easiest of the programminglanguages. Millions of people learned BASIC during the pioneer yearsof microcomputing, and GDL remains the most useful and practicaldescendant from BASIC. Experts who used to say that BASIC wasnot powerful enough for commercial applications can be confoundedby a well written piece of GDL. ArchiCAD users who make the boldstep of tackling GDL are frequently surprised at how easy it iscompared with what they expected. Users can suddenly find apractical use for all the mathematics they learned at school.

Total beginners can please themselves with rapid progress up thelearning curve. They can make objects that impress their friends andcolleagues, and genuinely improve the quality of their work.

Experts in GDL continue to find additional depths and techniques inGDL. With energy and programming experience they can extend thepossibilities. As soon as they begin to feel they have reached the limit,

Graphisoft’s next edition of ArchiCAD provides new areas ofexploration and power.

The ArchiCAD experience

You may wonder if you can learn to make good objects without

knowing too much about ArchiCAD. Well you can, but it really paysto have a good knowledge of ArchiCAD as a working tool – the useof the 3D and 2D elements; the use of techniques such as the Magic wand and the Marquee; splitting, mirroring, resizing andmultiplication.

If you are a regular user of ArchiCAD you will also develop a feel for what you like or hate about objects – do they stretch mindlessly, arethey difficult to pick up or snap to, are they transparent when theyshould be opaque, do they look clumsy in 2D, can you understand theparameter descriptions?

A critical appreciation of the experience of the user will help youmake better objects.

Spelling and grammar

A note for pedants: in the text, some words are capitalised oritalicised for emphasis or because they are titles e.g. the Wall tool. Inother cases you may find spellings that you do not agree with e.g.colour, metre. Largely, we have used English rather than Americanspelling in the English language edition.

For the countries which use commas as a decimal point, please note:in GDL, commas are separators, period (stop) symbols are decimalpoints.

You learn by looking at the objects

Try to get the objects that are illustrated in this book from a CD or Website, and work through them as you read the book.


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Read about Object Making

Besides this book, you can read about object making in other manualsand guides:

ArchiCAD Reference Guide – see table of contents and index of that volume. In particular, peruse the section on “Parametric Objects”

(Tools chapter). It is an important complement to this book and it would be repetitive for me to reprint it all here – but it contains very valuable information on object making.

DXF/DWG Conversion Guide : Bringing in objects from other CADenvironments.

ArchiCAD Training Guide : Making library parts (see table of contentsof that volume).

GDL Reference Manual : Syntax of GDL commands, in depthinformation on every aspect of GDL except programming.

Help Menu in ArchiCAD : Syntax of GDL commands, more frequentlyupdated (when versions change) than the Manual, this book or theCookbook.

Not included with ArchiCAD, but obtainable:

The GDL Cookbook: Project-based approach to learning GDL thatteaches both GDL and the technique of programming with GDLfrom beginner to expert level.

Project Framework: Discussion of how to get the most out of ArchiCAD in the professional office, with good explanations oforganization of your libraries.

You could also consider keeping a personal notebook of yourprogress with object making. By noting your successes, you can buildup a personal fund of expertise.


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CHAPTER 2: OBJECT M AKING WITHOUT GDL 1

Before learning GDL it is wise to become fully conversant with object making using ArchiCAD’s own tools.

2.1 Making Objects without GDL

Most ArchiCAD users become skilled at making objects using thenormal building elements in the Tools palette before they tackleGDL. For ArchiCAD newcomers, let’s make sure you are fullyconversant with object making before moving on to discover thepower of GDL.

Three methods of saving an object from ArchiCAD

Make the object using the Slab, Wall and Roof tool, and select it in thefloor plan window with the cursor. Then use one of these threemethods:

1 If the object has been made the right way up, or on its side, view in the 3D window in plan or elevation respectively. Savethe resulting view as a library part – use File>GDLObjects>Save 3D Model as... to save it as a .GSM object, window or door. Save it into one of your loaded libraries.

2 If the object has been made the right way up in 3D or if it is2D, use File> GDL Objects> Save Selection as... to save itinto one of your loaded libraries.

3 If the object is 2D, use File>GDL Objects>New Object...

and when the GDL dialog appears, click the 2D Symbolbutton and draw it into the 2D symbol window – or paste insomething you drew earlier in the floor plan. Set the A and Bdimensions to the size of the object in your drawing.

Processes 1 and 2 are called ‘Autoscripting’. ArchiCAD creates aGDL library part, with 3D form (if any) and either 2D scripts orsymbol, and routines to provide stretchiness. Every object, 2D or 3D,has an imaginary size-defining cuboid around it of ‘A’ for width, ‘B’for depth and ‘zzyzx’ for height. Method 1 and 2 will set this sizeautomatically; for 3 you have to set the size.

When you have made such objects, open them using File>GDLObjects>Open Object... – you will be able to view the scripts – a

highly educational process! The format of GDL script it generatescould be called ‘industrial’ – quite off-putting in appearance and a lot

more complicated than the ‘Creative GDL’ that you can attempt withthe help of this book.

Getting started with Object Making

Before making your first object with the Tools palette (withoutGDL), ensure that you are or you will become conversant with someof these basic ArchiCAD using skills:

• The use of the Magic Wand (for transforming a Fill to a Slab, or aSlab to a Roof, Line to a Wall etc.)

• Setting Grids, large and small, and setting dimensional preferencesto work with Metres or Decimal Inches.

• Using the Coordinates palette to make things accurate.

• Using the Settings dialogs for the various tools in the Tools paletteto get their materials and heights correct.

• Using Add-ons like Profiler and Trussmaker.

• Discovering the useful ready-made bits of GDL in the ‘Specialconstructions>Basic shapes’ library.

• Using the Marquee tool and 3D Cutaway to cut objects.

• Solid Element Operations (new in ArchiCAD 8).

• Making curved edges in slabs and fills with the Pet Palette.

• Setting up 3D Projection Settings to arrange camera and viewingangles correctly.

• Making Section/Elevation windows and copying and pastingbetween those and the floor plan.

• Multiply, Rotate and Mirror.

• Align texture – set origin and set direction.

Setting up

Open a new ArchiCAD file, load your standard library, and load anew folder to use as your working library and save the new file to thatfolder or to somewhere convenient. Set the large grid to 12” or to 300


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mm and the small grid to 5mm or 0.2”. Zoom in to somewhere nearthe Origin of the Floor Plan, so that you are viewing an area of thegrid that is a little larger than the furniture you wish to build. Try to work at or near the real origin, not a temporary one. Hairlines help with 3D building, True line weight helps with making 2D objects.

2.2 Let’s make something in 2DLet’s try making some 2D bathroom fittings. There is no scripting todo, it can be drawn with 2D tools. You could use this procedure forelectrical symbols, kitchen or bathroom furniture, or as a personalisedsymbol for trees and plants.

There are two ways to do this: draw the object in the floor plan usingLines, Arcs, Fills, Hotspots and Text. Select and File>GDLObjects>Save Selection as... an object into a loaded library (method2). You are advised to use mainly the Fill tool with opaque fill, so that

the object is solid against a coloured background and not transparent.Be warned that the object is not scale sensitive, so text and line widthsand vectorial fills may appear differently according to the scale of thefinal drawing.

Bring it straight back by selecting a library part from the Toolbox andplacing it in the Floor plan next to the original drawing. Normally, themost recent library part saved is the first object that appears whenyou place an object in the plan.

If you now Open the Object (from the File>GDL Objects menu)you will find that the 2D view is scripted, including all the hotspots

from the original drawing. This object may be saved as‘bthrm_whb.gsm’ and the other two objects may be saved with namesto match, e.g. as ‘bthrm_wc.gsm’ and ‘bthrm_bidet.gsm’.

The other method (3) is to create a New Object (from File>GDLObjects>New Object) and from the GDL dialog, hit the 2D Symbolbutton to get a 2D symbol window and draw the symbol directly intothat window (or paste it from the floor plan drawing). Check the sizeof the sanitary fitting, and set the A (width) and B (depth) values inthe parameter table correctly, or your drawing will be distorted whenit is an object. One benefit of method 3 is that you can return to addmore detail to the drawing in the 2D symbol window and you candecorate it with the hotspots of your choice on key parts of theobject, like the corners and the plugholes. If you do not add anyspecial hotspots, you will get 5 ‘bounding box’ hotspots – so addthose hotspots.

Set the A and B to the correct dimensions

You will not have to do this too often because the ArchiCAD libraryis well equipped with 2D objects, and many of the 3D objects fromthe ArchiCAD Library have a ‘2D only’ mode in which the 3D can be

omitted.

2.3 Bring a file in from DXF/DWG

If you want to bring in some 2D from DXF/DWG, bring it in to thefloor plan first. Then you have the option to clean it up, get the scaleright and make it into a 2D Library part as in the earlier section. When you want to bring the 3D DXF/DWG into ArchiCAD, bring itin as a GDL library part. The procedure is File>GDL Objects>OpenObject. Look for ‘Files of Type...’ and select either the DXF or the

DWG. Click on the file you want. You can opt for Default Translator. The Default Translator brings a 3D DWG in as GDL Script. Save theobject, then place it in the floor plan and open the object: look at the


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scripts. All the 2D and 3D data was imported, but you may be faced with colossal quantities of script.

You may be disappointed with the result. Nothing brought in fromDXF/DWG is solid; it seems to be a vast mass of polygons and lines,and in no particular order. If you attempt to edit these you will need alot of luck and guesswork. The most you can be sure of editingsuccessfully is the 2D symbol, and in the 3D, some IF statementsadded by you to hide or show portions; and insert some material andpen numbers.

3D objects may come in on their side, or the wrong size due to yournot knowing if they are created in millimetres, inches, feet or metres.If the object is the size of a pinhead or larger than your town, youmay have to ‘duplicate’ the Default Translator and amend the scaleconversion of the import. It may also be many kilometres from theOrigin.

Solids may be inside-out hollow things. You may find that the lack ofcontrol over the number of polygons leaves you with a model that hasso many polygons that your rendering times become unacceptable.

Many objects can be found by some smart searching with Google.Check the file format before downloading. Choose the DXF/DWGif you have a choice. Always take the opportunity (exert your‘consumer power’) to ask manufacturers of components to provideobjects in GDL.

This model of the Eiffel Tower comes in perfectly from DXF directlyfrom the Eiffel Tower’s own website. Unfortunately, it’s lying on its

side, and only 150m high. You have to be prepared to do some fixing,e.g. rotating it upright, making a new 2D symbol and resizing itcorrectly in height and plan area.

2.4 Let’s make a 3D Object – a Table

The next object, a Table, is to be made ‘the right way up’ and for this,the Slab tool is the most useful tool. Build up the table, starting withthe table top, and add the legs and frame. For each part, use thesettings dialog box to get the height of the slab correct. Rememberthat the height (altitude) of the slab is the top and the thickness is theamount of slab below the top. If you build from walls, the altitude ofa wall is its base, and the height of the wall is above the base.

It helps you later (if you want to tweak some of the GDL) to buildover the main origin. If you have made a temporary origin somewhereelse and the main origin is greyed out, just select the Origin tool and

click on the grey main origin.

We can use the curving function in the Pet palette to soften the edgesof the object. Remember also that you need to set the materials of thetabletop and legs using the Slab settings dialog box. A cylindricalelement like the chair leg could be made by magic wanding a slab to acircular arc, or by bringing in a cylinder from the ArchiCAD Library.Perhaps the best way is to use the Column tool, set to the rightdimension and materials.


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To make sure that each leg is consistent, make just one leg correctly atfirst. Next, Edit>Drag a Copy to the other end of the table. If thisoption isn’t available, use Options> Preferences>Miscellaneous toactivate the ‘Show Element copy...’ button. If you use the grid, youcan make the table reasonably accurate in dimensions. Keep an eye on

the Coordinates palette as you type in your X and Y locations and youcan make the table totally accurate. This is easier if you set Grid Snapto ON, and use a small grid of say 10mm or 3/8”. Make the tableabout 750mm (30”) high.

When you have built the chair, select it and using 3D ProjectionSettings, view it in 3D hidden line, in Plan with the camera at 270°.Save it using File>GDL Objects>Save 3D model as....

Now click on the object icon in the Tools palette and place it in thefloor plan. The result is indistinguishable from the original, but theGDL object can be placed as often as you need, it will appear inlistings and can be used in other building models. This table will bestretchy, but if you stretch it, the section sizes will deform – so build itthe size you want from the star t if you want to avoid distortion.

No matter how well you make it this way, it will never permit you tomake parametric alterations to height, leg spacing or timber sizesunless you are prepared to dive in and do some editing in GDL.

We will cover the editing of ‘industrial GDL’ in a later chapter.

2.5 Let’s Make a 3D Window with slabs

Windows have to be made flat on the floor, and are best made withthe Slab tool. Again, it is best to build it over the origin, and the origin


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should be symmetrically at the centre of the lower sill of the window. The external face of the frame must lie at a height of project zero onthe ground plane. Normally, slabs have their tops on the groundplane, so be careful to set your window frame at the right height andaltitude.

Draw out a rectangular slab first which defines the overall opening

size. Then select this slab, and with the Slab tool selected drawanother rectangle within the first slab. This draws a hole in the slaband effectively makes the frame hollow. A better way to do it is tomake the frame from four separate pieces. In this era of Open GLyou want to try to get better texture rendering – look at the woodgrain – GDL organises the grain separately for each piece. Setthe material of this slab to frame material. You can now draw anotherslab into the window, set this to 20mm (3/4”) thick and set it to‘Glass’ for top bottom and sides. Make sure the height of the glass is well positioned in height, within the frame. For added realism, you

can add a smaller group of frame sections to play the part of acasement, and a small slab below the project zero to be a sill.

The illustration above shows how the window should sit on theproject zero ground plane. Check that the frame/casement/glassrelationships are working correctly. Use a Section/Elevation view toget it perfect, including the glass position.

In this case, the project origin is neatly positioned at the centre of thesill. This is not absolutely necessary because ArchiCAD will make

adjustments when it saves the window so that the origin finishes up inthe right place. But it is tidy and more disciplined to get it right at thestart.

When you are done laying slabs, select all the slab elements of the window, and view them in Plan (270°) just like you did for the table.Use a wireframe view to show the frame. Although you are viewing it

in plan, ArchiCAD will turn it the right way round for it to work as a window in a wall.

Save that 3D view as an Object and when asked, click on the‘Window’ icon. Check the box that hides redundant lines. Make sureyou save it into a loaded library. If you have not already done so, makea folder in your personal library for windows and doors as you save.

If you clicked the window or door icon, ArchiCAD will recognise thatit has to cut a hole in any wall. The hole size will be the width anddepth of the window you made.

Back in the floor plan, build a wall, and then select a window to putinto it. Select the window you have just saved. Place it into the wall,making sure that the Eyeball cursor is clicked to the outside face ofthe wall (the face with more hotspots). You can now view the resultand change its parameters – of size only.

One unfortunate finding is that the textures can be perfectly alignedin the object itself, but in the wider ArchiCAD environment, the wood textures behave differently. The way to guarantee perfecttextures is to use Edit>Align 3D texture on each part of the frame

before you save the window object.


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The technique of making windows is similar to door construction.But you would need GDL to change the window or door styles, tomake it open and shut, add grilles, or offer a choice of glazing or

ironwork styles.

Before you move on, you would find that the 2D symbol (see figureat right, in illustration above) is too horrid to use in a plan. The curvein the window head produces a lot of spurious lines. You should openthe Window as a GDL object, click on the 2D Symbol button and it will open up a drawing window, enabling you to delete the bad linesand clean up the pen thicknesses (left side, in illustration above).

Unusually shaped windows – ‘wallhole’ idea

Actually, this example is so simple that you find adequate windowslike this in the ArchiCAD library already. Windows like this only cut

rectangular holes in the wall. What you may need is a window of amore unusual shape. The trick is to lay a roof or a slab over the

outline of the window, and give it an ID of ‘wallhole’. We will explainthat more fully in chapter 10 on windows.

2.6 Let’s make a Chair using Wall tool

Many objects are easier to make lying on their side, because of their

complexity or shape. They may be far easier to build in profile than tobuild as a stack of slabs or walls assembled vertically.

You can make skillful use of the Wall tool. Walls are most useful asthey can be set to a thickness and height and can be snapped tofollow lines with the Magic Wand. They are more controllable atfollowing curves than the Slab tool. Their only trouble is theirannoying tendency to join together and form strange spiky mitringeffects when you least want it. In the Display Options you could turnoff Clean Wall Intersections for straight lined objects. To get thesecurvy walls working, we should retain Clean Wall Intersections.

This Bentwood chair illustrates the use of the Wall tool perfectly – itcould be made with the Slab tool but only with more difficulty.

Making the Frame and Seat

First, using the 2D line tools, draw the outline of the chair frame,including the curve of the arms using 2D lines. Then set the Wall toolto be your choice of Wood material, 30mm (1.25”) thick and 150mm(6”) high. Magic Wand the Wall tool to the lines (click with space bardown); this causes the little walls to follow the lines. Ensure that the walls are grouped; drag a copy of the wall group to one side. Now usethe Elevate command to raise that wall group by 600 mm (24”). Movethat wall group back until it is exactly over the first. You now have thebentwood frame of the chair. Using the same wall setting, put in the


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straight sections for the seat and back. Change their heights to startfrom 150mm (6”) above the deck and finish 600mm (24”) high – as inthe illustration.

Duplicate the seat and back walls, and make them about 90mm (3.5”)thick and change material to fabric. You can use the wall-end featureof ArchiCAD 8.1 to get rounded ends, or get the same outline with

the Slab tool. To finish, the chair has some little black hinge bolts forthe connecting rods, which can be a small but very high slab.

Try using the Log setting in the wall, set to 30mm (1.25”) log heightsto simulate bamboo for the arms. It works on the straight bits, butnot on the curves. For this effect, you will need real GDL.

Stand it upright in 3D

When you have something like the Bentwood chair in the diagram,lying fully on its side, it’s time to rotate it upright. Set the 3Dprojection setting in the parallel views to 90° position for camera

with elevational view selected. Save the 3D view as a library part intoyour loaded library; this time, click the object icon (not the window ordoor) and tick the ‘Editable’ radio button, and tick the redundantlines checkbox.

Place the chair into your project and enjoy! In this view, the finishedchair object admires its creator with satisfaction. To improve it, youmight edit the 2D Symbol (as you did for the window) to eraseextraneous lines.

Give the object a Preview Picture

If you are pleased with your object, capture a small rendered view ofit with the image size set to 128x128 pixels. Select it and copy. Openthe object’s GDL dialog, click the Preview Picture button and pastethe image into the Preview Picture of the object. It will look better in

Windows/Finder and will be much easier to pick from the Objectbrowser.

You can paste any image that is near-enough square into the PreviewPicture, but it will be rescaled by GDL. Pasting in a 128x128 ensures adistortion free image.

You do not need to use ArchiCAD for the image. It could come froma photo, or a company logo.

2.7 Let’s make a Roof Truss with Fills

Try this exercise, which provides a link between the section/elevationand the floor plan windows.

Construct a small one-room building, and place a pitched roof over it.Make the walls higher than the roof and then use the Trim to Roofcommand to make the walls and roof fit each other. Insert a windowand door if you like. Now using the Section/Elevation tool from your Tools palette, draw a section through the building, and view thesection.


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This homely interior (rendered in ArchiCAD) needs some timber trusses.

Draw Fills into the Section

View the section. You can make use of the Line tool to set upguidelines to make sure that your timbers line at the right angles andhave the right depths. When you have the section in the foreground,you can only draw with the 2D tools. Use the Fill tool to outline asmall truss. This ensures that your future truss will fit the roofperfectly. Select the fill and continue to draw into it. If you need any

holes, you can cut holes in the fill. Thus you form the outline of the

whole truss. In this case, use a separate Fill for the Steel wires, the Timber and the Circlebolt.

Now select the fills, copy them, move to the floor plan and pastethem. Move them to a clear space, and it would help if one end cornerof the truss is over the Origin – perhaps one of the truss bearings. The hotspots will help you. Now you can magic-wand the Slab tool to

follow the outline of the Fill, and to cut any holes you might have(there are none in this truss).

Making the 3D with Magic Wand and Slabs

Make sure before you use the Slab tool so that it is centered on theground plane – in this case, for the timber set the thickness to 100mm, the top of the slab to 50 mm and the material to timber. Thusthe truss is nicely centered above and below ground zero. You willmake similar settings for the Steel wires and the circle bolt.

You may have a bit of trouble with the Magic Wand. Snap-click to the

outline of the fill first to get the outline of the truss. If there are holesin the truss, select the new slab, select the slab tool again (making sureit is the slab and not the fill by looking at the Info palette) and thensnap-click any of the holes in the fill. This will drill holes in the slab.

You should finish with a small truss like the one illustrated. If youmake a mistake, delete the waste slabs and try again with the sequenceabove. Make yours more complicated if you want to, with moremembers, or more varied width of members, and add extra metalplates for extra realism.

Keep the two sides of the truss separate by splitting the slab at the

apex; do an ‘Align Texture’ for each side for the wood grain. This willlook good in the finished object. Now select and view the truss from


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the 90° camera position in parallel elevation view. Save the 3D view asa library part, click the object icon and you have your truss, withtexture alignment.

Tidy up the 2D Symbol – add hotspots

Now bring this truss into the floor plan. Open it as a GDL object and

edit the 2D Symbol. Place 2D hotspots at the apex and at the bearingpoints where the truss meets the wall. This makes it easier to place inthe model. Place one truss into the building and look at the originalSection view. Use the view to get the first one the right height andposition relative to the wall – make sure your truss aligns perfectly with the original fill pattern. Autoscripted objects are automaticallystretchy so be careful when handling them – you do not want tostretch them accidentally. Use Edit>Drag a Copy or Edit> Multiply>Distribute to move and duplicate them, and use the Coordinatespalette if you want exact spacing.

This same method can be used to make complex structures – thelimitation being that they will not be parametric, and they will all berectilinear in section. Trussmaker is good for most trusses if madefrom a single material. This method is good for composite wood-steeltrusses. Remember that single slab objects made this way will have thetexture all one direction and will not look authentic unless you do it inseparate pieces as we did for this truss.

Now the inhabitants have a nice steel tied timber roof!

Summary of Object Making in this chapter

• You can make complex objects without GDL using the 3D toolsor using library objects that already exist. They will be stretchy butnot smart, and not parametric in anything except stretchiness.

• These can be 2D or 3D and can be saved from the floor plan, or

from the 3D view.• Windows and Doors can be made without scripting GDL.

• The Wall tool is powerful for object making without GDL.

• Using the Magic Wand, you can ‘steal’ shapes from 2D ArchiCADand turn them into Objects.

PART ONE OBJECT MAKING WITHOUT GDL


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CHAPTER 3: OBJECT M AKING WITHOUT GDL 2

Even without GDL there are techniques of object making that go beyond the simple use of the standard ArchiCAD tools.

3.1 Using Basic Shapes from the Library

You can make more complex or curvy objects using library parts thatare in one of your loaded libraries. The standard ArchiCAD librarycontains a directory of special structures such as cones, curved tubesand vaults. Before you try to do this, just check which libraries areloaded (File menu>Load Libraries) and if it’s not already in, load the ArchiCAD Library.

If you have an object-making add-on like Trussmaker , ArchiForma orGDL Toolbox , consider whether you can make your object with one ofthese more easily.

Make a ‘Banana’ Truss or Mullion object This banana truss has been built entirely from the ‘elbow’ and‘cylinder’ objects in the existing ArchiCAD Library. The key is placingand configuring them, and thinking out which way to organise thecamera direction. In this process, you are making parts of the truss,saving them, bringing them back in, grouping, then resaving –‘nesting’, or ‘encapsulating’. Some of these components aresomewhat confusing to manipulate. Once you have done the firstsave, you lose control over parametric changes, as the objects whichfollow are the ones you saved. So place them correctly at each stage.

This object starts with the ‘Elbow’. Lay it down flat on the ground(centre of the tube at ground zero) and configure it to the length you want. Use 2D lines as guidelines. Place some single cylinders of asmaller diameter (see below) to form the bracing tubes.

For the next step, it’s easier to rotate it 90°, so we can save it as an upright truss.

Here the elbow has been placed and stretchy cylinders laid. Now save this with thecamera at 90° in ele vational view.

Bring it back in to the plan, twice, and it should be upright, as in thenext illustration. The upright truss halves can be splayed at the angleyou wish to achieve, and then reviewed and resaved. Add in a columnto form the long straight tube.



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Save again, with the camera at the same viewpoint, in elevation. You need great

precision in placing them in relation to each other.Bring it back in, this time laid flat on the ground. It’s time to add inlinking cross tubes. You will need the sectional view to get the preciseposition and height of each cross tube. In the plan make sure that thecylinder ends are ‘lost’ inside each main curving tube. View it in 3DPlan, 270° and you can save it as a horizontal 3D Truss.

You could view it one more time in 3D Elevation, 90°, and save a version of it, upright, for use as vertical wind resisting mullions – which is what I intended to make originally.

Remember that if you ever wish to view the final object, you willalways have to be able to find the constituent parts in a loaded library.If you alter one of the components, it may result in an error when the

final object is viewed. We have become used to seeing the ‘Missingobjects’ dialog box coming up at some time or other. This is useful; ifyou read it, the warnings of duplicate library objects and of missingones require action.

If the composite object never needs to be edited again, then youcould view it once more in 3D plan view from an angle of your choiceand then save as a Binary. This ensures that all the subsidiary objectsare included and wrapped up into a new bundle of polygons and andyou do not need to worry about missing the earlier components.

A final finish would be to open it as a GDL object and plant somehotspots into the 2D Symbol to remove the bounding box and makethe truss easier to pickup and snap to wall surfaces.

3.2 Let’s make an Object by Cutting

The banana truss/mullion is an example of nested objects (objects within the larger object). As another example of nested objects, we


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Plan of the shimmering marquee over the vault object. The thin 2D lines ensurethat your cutter is at exactly the right angle. Use the Coordinate Box if you like totype the angle in. Now you see the groin vault part in 3D.

View this in 3D axonometric and you will find that you have a groin vault mitred at 45°. If the cutting effect does not occur, close the 3D

window, use the Display> Rebuild command, and then try 3D again.If it is cutting correctly, use the 3D projection settings to set thecamera position to 270° and the view type to Parallel>Plan. Save thisas a library part and you can call it ‘vault_part2.GSM’.

Return to the floor plan, and place your new vault piece. Now thisobject has default ‘Bounding Box’ hotspots. You can make your lifeeasier – open the 2D Symbol in the GDL dialog and customize yourhotspots. Place your own 2D hotspots at the corners, including one inthe middle. Zoom in real close and place one at the pointy apex of thegroin-vault.

Personalised hotspots will remove the bounding box. The hotspot atthe pointy corner can now be used as a hinge around which toEdit>Multiply>Rotate.

Place the result next to a piece of straight vaulting and you can nowgroup these two. Now use Edit>Multiply to Rotate yourself anotherthree and you have the complete groin vault!

Picture of the four vaults in 3D axo

You can now add in more uncut vault objects alongside these, stretchto appropriate lengths and before you know it, you have your churchroof. You can use the same technique with the polygonal marquee to

take a sideways ‘bite’ out of a large vault and have a pair of smaller vaults intersecting.

Try making a Doric column with Profiler, add a square base top andbottom. Bring it all together.

All this can be done without GDL, and yet, when they see it, yourfriends and colleagues will be convinced you have become a GDLexpert.



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Picture of the final structure, with the groin vault, and some columns made withProfiler, and a window made with little walls.

3.3 Urban Modelling

Urban modelling – entire buildings as objects

Entire buildings can be library parts. ArchiCAD is a powerful tool forbuilding modelling. A finished building is an elaborate combinationof layers, stories, library parts and building elements – it is not easy to

transport to another model. In a city, every building has differentstory heights and different layer titles. An urban model is going to beconcerned with city blocks, street furniture and landscape, andbuildings are just a small part of this.

If you are doing urban modelling, many buildings will be singleforms, but the special buildings with a higher level of detail are bestbuilt in another plan and brought in as individual library parts.

If you wish to include buildings from another project, open the file ofthe building, try to make the windows of ‘Ice’ or of a less transparentmaterial, hide all layers to do with internal furnishing and small details

(unless they need to be seen through windows) and hide the site on which it sits. Then select the entire building using the fat (thick lines)

marquee, and view it in 3D in plan view. Either way, you will get allstories showing. If you had a basement that you wished to omit, thenuse Image>Elements to Show in 3D... dialog and you can decide which stories to omit. Save as an object.

If you save it as ‘Editable’, you are in danger in the long term of losingthe subsidiary library parts (such as windows) that it was built from. It

may also fail to render due to spurious errors such as missing parts orbad polygons. Save as ‘Binary’, and you can safely export it to yoururban model; place it anywhere and at any height and it will work. You would need a copy of the original if you wish to go back andmodify any part of it, as the only editing you can do to a binary is tomake it stretchy – so store the layer combination.

If you do not want the binary building object to be stretchy (to help with selection), open the 2D symbol window of the GDL object, andplace 2D hotspots wherever you think would be most appropriate –corners, turrets, entrance canopy, ridges, etc. and then save again.

That will turn off the bounding box hotspots.

Proposal for a 43 storey tower for Central London by Robert Luck. You can just

see Tower Bridge in the far distance. the entire central area of London is a low polygon count object.



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If you only need facades, you can build an entire facade on theground, using the Slab, Wall and Roof tools. Then save it using the3D view with the camera at 90° in the Parallel>Elevation view. Bringit back into your floor plan and assemble the building from facadelibrary parts. Again, we advise that these are binary, to avoid any lostsubsidiary components, and to reduce the risk of rendering errors. A

disadvantage of this method is that you cannot use normal Windowand Door objects in the library – but it’s great for areas of curtain walling.

If the object is binary, you can change its materials at a stroke to asingle one in the object settings box – untick the ‘Use objects ownmaterials’ option. Try changing it all to ‘Ice’ for the ‘Sketchup’ effect!

Urban modelling – entire sites can be objects

The converse of this idea is probably more commonly used. Yourbuilding may have a lot of detail; the site model of its surroundings

may be larger in area but it may have fewer polygons than thebuilding.

Make the site separately, save it as an object, and bring it into thebuilding model, in a lower storey. This way, you can hide or show thesite at a single moment using layers, or change its materials fromrealistic to ‘Ice’ or ‘Whitewash’ ‘Pine, shiny’ in a moment. You canupdate the site by going back to the original site model and reviewingin 3D and resaving. For this to work best you must not alter the widthand depth . If you alter these, the autoscripting routine will repositionthe bottom left corner and thus the object’s position in your other

model. Placing an oversize 2D rectangle around the large model andmagic wanding the marquee to the rectangle will maintain a consistentboundary size.

Urban modelling – the Camera is the mightiest

weapon!

While not wishing to suggest that Lara Croft’s environments aremodelled with ArchiCAD, the point here is that you can use texturesmore vigorously. Open GL has changed the situation remarkably – itis far quicker to model urban environments with the greatest

simplicity in 3D and then apply textures. If you cannot photograph anentire building, you can reconstruct its elevation from photos of theentrance, and main fenestration and roof features, and copy and pastetogether the whole facade. This technique is so important, we havethe whole of chapter 9 dedicated to it – ‘Billboard Objects’.

The textured facades are so much more realistic than trying to use 3D modellingtools (as in the foreground, above).

3.4 Making Objects with Add-ons and Solid

Geometry

Progressing from the standard ArchiCAD Tools, we can make use ofsome of the object making Add-ons or functions. Profiler, Convert



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Mesh to Roof, Solid Element Operations and Trussmaker aremajor assistants to objec

Intro Object Making

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