FCG Lab04: Introduction to Panda3Dprojects.i-ctm.eu/sites/default/files/Lab_04_0.pdf · Where? .egg...

FCG Lab04: Introduction to Panda3D

Michele Svanera

Department of Information EngineeringUniversity of Brescia

02 May 2016

mailto:[email protected]

1 Introduction to Panda3D

2 Scene Graph

3 Task

4 Actors and Models

5 Render Attributes

6 Camera control

7 Install and References

OpenGL limitations

Low-level library!

Speaks graphic cards “languages” (translator functionality)

Portable and very fast

System independent

Useful for implementing basic functionality

simple objectstexture mappinglight sourcelittle animation

. . . and for something more complex?

. . . Animation? Interaction between objects?

Michele Svanera FCG lab04: Introduction to Panda3D 3


Panda3D: a game engine I

What is it?

Open-source (since 2002) game engine

Library of subroutines for 3D rendering and game development

Provides:

GraphicsAudioI/OCollision detection. . .

Set of C++ library with Python bindings [5]

Jointly developed by Disney and Carnegie Mellon University



Panda3D: a game engine II

Commercial and Open-source library. So 4 characteristics:

Power easy to implement complex scenes

Speed important frame-rates

Completeness contains tons of essential tools

scene graph browsing

performance monitoring

animation optimizers

Error tolerance all developers create bugs! Much code (it is anSDK) is dedicated to the problem of tracking andisolating errors. Panda3D almost never crashes!



The Use of Models

Usually here we don’t draw stuff

Boring. . .

Tricky to do procedurally

Not trivial to design “realistic” models

Usually ready-made models are imported into panda

Models are drawn with proper modelling tools:

Blender (we will see it the next time), Maya, 3DS MAXHigh-quality

Models can be animated by the engine

. . . Drawing is still possible!



Panda3D books

“Panda3D 1.6 Game Engine Beginner’s Guide”,by Dave Mathews

“Panda3D 1.7 Game Developer’s Cookbook”, byChristoph Lang

Panda3D Manual [14]

Panda3D Forum [13]




2 Scene Graph

3 Task

4 Actors and Models

5 Render Attributes

6 Camera control


The Scene Graph I

“Tree of things to render”:

More flexible than lists (as manyother engine uses) and inheritance

An object is not visible (andrendered) until it is inserted

Objects are children of (super)classPandaNode

ModelNode

GeomNode

LightNode

. . .

. . . usually refer as generalNodePath.



The Scene Graph II

Something to know about the tree

The root of the tree is called render

Each node attributes are inherited by the children (ex.position)

Possibility to manipulate the tree, NodePath helper class

pointer to a node (in reality it’s something more... “handle”)

when you invoke a method of NodePath, you are actuallyperforming an operation on the node to which it points



The Scene Graph III

Panda3D generates bounding boxes for each node in the tree

Number of methods dedicated to finding nodes and returningthe NodePaths



The Scene Graph IV



The Scene Graph V

Example 1: Solar System



The Scene Graph VI

Example 2: What makes a man?



Dealing with nodes I

Loading models

NodePath np = window ->load_model(framework.

get_models (),

"path/to/models/model.egg"); //ready -made models

can be found under "models /"

Manipulating nodes

np.reparent_to(window ->get_render ()); // attach

this node under root

np.detach_node (); // remove node from tree

np.remove_node (); // delete node: releasing memory

Create empty nodes

NodePath dummyNode = window ->get_render ().

attach_new_node("Dummy_Node_Name");

myModel.reparent_to(dummyNode);

myOtherModel.reparent_to(dummyNode)



Dealing with nodes II

Setting attributes:

np.set_pos(x, y, z);

np.set_hpr(Yaw , Pitch , Roll);

np.set_scale(s); // object ’s size; set_x () _y()

// Store current transform information

np.get_pos ();

// Rotates a model to face another object

np.look_at(otherObject);

// Color: floating point numbers from 0 to 1, 0

being black , 1 being white.

np.set_color(R, G, B, A);

// Temporarily prevent an object from being drawn

np.hide();

np.show();

Notes1

1An object’s rotation is usually described using Euler angles called Heading,Pitch, and Roll (sometimes called Yaw, Pitch, and Roll in otherpackages)–these specify angle rotations in degrees.




2 Scene Graph

3 Task

4 Actors and Models

5 Render Attributes

6 Camera control


Task I

Special functions (subroutines) called on each frame:

Similar in concept to threads

All tasks run cooperatively within the main thread

Defined by GenericAsyncTask class

The function receives one parameter: the task object

Each task carries information about itself (ex. amount oftime)

task->get_elapsed_time() //how long task runningtask->get_elapsed_frames() //number of elapsed frames. . .

Each task returns after it has finished processing the currentframe:

AsyncTask::DS_cont = call it again the next frameAsyncTask::DS_done = finished, don’t call it anymoreAsyncTask::DS_again = perform it again, with same delay



Task II

Generic Task

AsyncTask :: DoneStatus your_task(GenericAsyncTask* task

, void* data) {

// Do your stuff here.

// ...

// ...

// Tell the task manager to continue this task the

next frame.

// You can also pass DS_done if this task should not

be run again.

return AsyncTask :: DS_cont;

}



Task III

Task example

#include "asyncTaskManager.h"

// This task runs for two seconds , then prints done

AsyncTask :: DoneStatus example_task(GenericAsyncTask*

task , void* data){

if (task ->get_elapsed_time () < 2.0){

return AsyncTask :: DS_cont;

}

cout << "Done" << endl;

return AsyncTask :: DS_done;

}



The Task Manager

All tasks are handled through the Task Manager object (list)

TM can be initialized by

PT(AsyncTaskManager) taskMgr =

AsyncTaskManager:get_global_ptr ();

Adding a new task can be done by

PT(GenericAsyncTask) task;

task = new GenericAsyncTask("taskName", &

function , (void*)NULL);

taskMgr ->add(task);

Tasks con also be removed by task->remove()



The Task Chain

Each TaskChain is a ordered list of tasks that are available tobe executed

Add tasks to the TaskManager = adding in default Task Chain

TaskManager can maintains one or more task chains

You can create additional task chains as you see the need

Each task chain has the option of run in parallel with others

Normally, no reason to have more than the default task chain(unless threaded tasks)

New task chain

AsyncTaskManager *task_mgr =

AsyncTaskManager :: get_global_ptr ();

AsyncTaskChain *chain = task_mgr ->

make_task_chain("chain_name");



Exercise: Rotating Cube I



Exercise: Rotating Cube II




2 Scene Graph

3 Task

4 Actors and Models

5 Render Attributes

6 Camera control


Actors and Models

Two main classes for 3D geometry:

Model for nonanimated geometry (static)

Actor for animated (if it changes shape) geometry(dynamic)

Where? .egg file

Used to store Geometry

May contain Model, Actor, Animation (to be applied to anactor) or both (better to pack in two .egg)

Are created by exporting models from 3D modeling programs:Maya, Max, or Blender (Lab06)



Loading Actors and Animations I

Actor operations:

Load the Actor Model

NodePath Actor = window ->load_model(window ->

get_render (), "models/panda -model");

Load the Animation

// the name of an animation is preceded in the .

egg file with <Bundle >

window ->load_model(Actor , "models/panda -walk4");

One-command animation

//bind models and animations + set it to loop

window ->loop_animations (0);



Loading Actors and Animations II

Control the Animations

// loop all animations

anim_collection.loop_all(true);

// loop a specific animation

anim_collection.loop("panda_walk_character", true)

// play an animation once

anim_collection.play("panda_walk_character");

// pose: hold a particular frame of the animation

anim_collection.pose("panda_walk_character", 5);




2 Scene Graph

3 Task

4 Actors and Models

5 Render Attributes

6 Camera control


Render Attributes I

After loading a model, you can alter its appearance by alteringits attributes (such as color, texture, lighting, and . . . )

All the attributes of an object are called the object’s renderstate

Setting an attribute on a node automatically applies it to allof the children of that node

Create and assign attributes to a node:

node_path.node()->set_attrib(attributeObject);

In many cases, there is a convenience function on NodePath(ex. node_path->set_fog()) that manages the creation ofthe attributes



Render Attributes II

Object’s render state:

AlphaTest Hides part of the model, based on the texture’s alpha channel

Antialias Controls fullscreen antialiasing and polygonedge antialiasing

Color Tints the model (only works if the model is not illuminated)

CullBin Controls the order in which Panda renders geometry

DepthTest Alters the way the Z-buffer affects the model

Fog Causes the model to be obscured by fog if it is far from camera

Light Causes the model to be illuminated by certain lights

Material Changes the way the model reflects light

ShadeModel Can cause the model to appear faceted instead of smooth

TexGen Causes system to synthesize texture coordinates for the model

TexMatrix Alters the existing texture coordinates

Texture Applies a texture map to the model

Transparency Causes the model to be partially transparent



Lighting I

Lighting a scene consists of two steps:

1 Creating lights, and positioning them within the scene

2 Telling which objects should be illuminated by the lights (andhow: Material)

Two general categories of lights:

Directional Light that comes straight from a particular lamp

Point: single point in space and shining in alldirections (like sun)Directional: infinite wave of light, always in thesame direction (like sunlight)Spotlight: sophisticated kind of light; has both apoint and a direction, and a field-of-view

Nondirectional Light that maybe came from somewhere

Ambient: uniformly distributed in the worldMichele Svanera FCG lab04: Introduction to Panda3D 32


Lighting II

// Point Lights

#include "pointLight.h"

PointerTo <PointLight > plightSun = new PointLight(

"sun"); // default white

NodePath plightSun_p = window ->get_render ().

attach_new_node(plightSun);

plightSun_p.set_pos (500 ,500 ,500);

window ->get_render ().set_light(plightSun_p); //all

world is illuminated

// Directional light

#include "directionalLight.h"

PT(DirectionalLight) d_light;

d_light = new DirectionalLight("my d_light");

d_light ->set_color(LVecBase4f (0.8, 0.8, 0.5, 1));

NodePath dlnp = window ->get_render ().attach_new_node(

d_light);

dlnp.set_hpr (-30, -60, 0);

myObject.set_light(dlnp); //only myObject is

illuminatedMichele Svanera FCG lab04: Introduction to Panda3D 33


Lighting III

// Spotlights

#include "spotlight.h"

PT(Spotlight) s_light = new Spotlight("my s_light");

s_light ->set_color(LVecBase4f (0, 1, 0, 1));

NodePath slnp = window ->get_render ().attach_new_node(

s_light);

slnp.set_pos(0, 5, -1);

slnp.look_at(myObject);

myObject.set_light(slnp); //only myObject is

illuminated

// Ambient Lights

#include "ambientLight.h"

PT(AmbientLight) a_light = new AmbientLight("my

a_light");

a_light ->set_color(LVecBase4f (0.2, 0.2, 0.2, 1));

NodePath alnp = window ->get_render ().attach_new_node(

a_light);

window ->get_render ().set_light(alnp);



Materials

Lights are used to express how much light is striking themodel

Materials are used to express how much of the light strikingthe model is reflected

The Material consists of four values:

Ambient Scattering How much of the nondirectional light isreflected

Diffuse Scattering How much of the directional light is scattered

Specular Reflection How much of the directional light is reflected

Emissive How much light the surface produces itself



Depth Test and Depth Write

Hidden surface removal

By default, depth buffer is enabled

//En-Disables writing to the depth buffer. Useful for

transparent objects

nodePath.set_depth_write(false); // Disable

nodePath.set_depth_write(true); // Enable

// Similar to glutInitDisplayMode (... | GLUT_DEPTH);

//Do depth comparisons and update buffer. Often used

for rendering things like h e a d s u p displays

nodePath.set_depth_test(false); // Disable

nodePath.set_depth_test(true); // Enable

// Similar to glEnable(GL_DEPTH_TEST);



Texturing I

Process that sticks an image on to a surface

Details of texture (ex. path, filtering or repeat-method) aresaved into the egg file of the model

(u, v) texture coordinates with u from 0 to 1 from left toright, and the v from 0 to 1 from bottom to top

u : from 0 to 1 around sphere

v : from 0 at the bottom to 1 at the top



Texturing II

#include "texture.h"

#include "texturePool.h"

TexturePool *texture_pool = TexturePool ::

get_global_ptr ();

// In main

NodePath myNodePath = window ->load_model(framework.

get_models (), "Square");

Texture *tex = texture_pool ->load_texture(

"myTexture.jpg");

myNodePath.set_texture(tex);

//Square.egg model comes from [1].



Texturing - WrapMode I

Texture coordinates can go outside the range (0 < u or u > 1)

Behavior managed by wrap mode

The wrap_mode is specified separately for u and v directions

texture ->set_wrap_u(wrap_mode);

texture ->set_wrap_w(wrap_mode);

wrap_mode options, starting from:



Texturing - WrapMode II

Texture::WM repeat The texture image repeats to infinity(default)

Texture::WM clamp The last pixel of the texture imagestretches out to infinity. When you apply atexture that is intended to exactly fill apolygon, you should usually set its wrap modeto clamp

Texture::WM border color The color specified bytexture->set_border_color() is used to fillthe space

Texture::WM mirror The texture image flips back-and-forthto infinity

Texture::WM mirror once The texture image flips backwards,once, and then the ”border color” is used




2 Scene Graph

3 Task

4 Actors and Models

5 Render Attributes

6 Camera control


Camera control I

Panda3D’s camera is considered a PandaNode: it can bemanipulated as any other node.

By default, panda runs a task that enables you to move thecamera using the mouse

This task will conflict with any code you write to move thecamera, like: camera.set_pos, camera.look_at

// Mouse control camera

window ->setup_trackball ();

// Position of the mouse

if (mouseWatcher ->has_mouse ()){

if (window ->get_graphics_window ()){

int x = window ->get_graphics_window ()->

get_pointer (0).get_x ();

int y = window ->get_graphics_window ()->

get_pointer (0).get_y ();

}

}Michele Svanera FCG lab04: Introduction to Panda3D 42


Camera control II

// Enable keyboard

window ->enable_keyboard ();

//exit function

void sys_exit(const Event* eventPtr , void* dataPtr)

{

exit (0);

}

//in main

framework.define_key("escape", "sysExit", sys_exit , (

void)* NULL);

"escape", "space", "f"+"1-12" (e.g. "f1", ..."f12"),

"backspace", "insert", "home", "page_up", "num_lock",

"tab", "delete", "end", "page_down", "enter",

"arrow_left", "arrow_up", "arrow_down", "arrow_right",

"control", "alt"



Exercise

(Only Section 1 - Creation of the scene)




2 Scene Graph

3 Task

4 Actors and Models

5 Render Attributes

6 Camera control


Install and References

Installing Panda3D in Linux (with problems solutions) [12]

Installing Panda3D in Windows [10]

Installing Panda3D in Mac OSX [11]

Panda3D Manual: Main Page (C++ & Python) [14]

Panda3D Documentation and References [15]

Panda3D Manual: Cheat Sheets [9]

Bullet Collision Detection and Physics Library [2]

Panda3D C++ Example [7]

Free Model [4] and [1]

Sample program [8]:

C++: make [6] and run

python: python2.5 name.py or python2.7 name.py



SDK contents

samples (or Examples) (only in python! See [7] for C++)

etc with configuration file Config.prc [3]

include with header files

models with already made objects



Alice gallery for models.http://alice.org/pandagallery/.

Bullet collision detection and physics library.http://bulletphysics.org/Bullet/BulletFull/.

Configuring panda3d.https://www.panda3d.org/manual/index.php/

Configuring_Panda3D.

Free models.http://www.turbosquid.com/Search/Index.cfm?

keyword=&certification_id=1&media_typeid=2&sort_

column=A5&sort_order=asc.

Language binding.http://en.wikipedia.org/wiki/Language_binding.

Make file example.Michele Svanera FCG lab04: Introduction to Panda3D 48

http://alice.org/pandagallery/

http://bulletphysics.org/Bullet/BulletFull/

https://www.panda3d.org/manual/index.php/Configuring_Panda3D

https://www.panda3d.org/manual/index.php/Configuring_Panda3D

http://www.turbosquid.com/Search/Index.cfm?keyword=&certification_id=1&media_typeid=2&sort_column=A5&sort_order=asc



http://en.wikipedia.org/wiki/Language_binding


https://dl.dropboxusercontent.com/u/44434712/

SVDRV_lab_2014/LAB04/Makefile_VM.zip.

Panda3d c++ example.https://github.com/drivird/drunken-octo-robot.

Sample example.https://dl.dropboxusercontent.com/u/44434712/

SVDRV_lab_2014/LAB04/ex-animation.zip.

Panda3D cheat-sheet.http:

//www.panda3d.org/manual/index.php/Cheat_Sheets.

Install on linux.http://www.panda3d.org/manual/index.php/

Installing_Panda3D_in_Linux.

Install on macosx.


https://dl.dropboxusercontent.com/u/44434712/SVDRV_lab_2014/LAB04/Makefile_VM.zip

https://dl.dropboxusercontent.com/u/44434712/SVDRV_lab_2014/LAB04/Makefile_VM.zip

https://github.com/drivird/drunken-octo-robot

https://dl.dropboxusercontent.com/u/44434712/SVDRV_lab_2014/LAB04/ex-animation.zip

https://dl.dropboxusercontent.com/u/44434712/SVDRV_lab_2014/LAB04/ex-animation.zip

http://www.panda3d.org/manual/index.php/Cheat_Sheets

http://www.panda3d.org/manual/index.php/Cheat_Sheets

http://www.panda3d.org/manual/index.php/Installing_Panda3D_in_Linux

http://www.panda3d.org/manual/index.php/Installing_Panda3D_in_Linux


http://www.panda3d.org/manual/index.php/Getting_

Started_on_OSX.

Install on windows.http://www.panda3d.org/manual/index.php/

Installing_Panda3D_in_Windows.

Panda3D forum.http://www.panda3d.org/forums/index.php.

Panda3D manual.http://www.panda3d.org/manual/index.php/Main_Page.

Panda3D lib reference.http:

//www.panda3d.org/reference/1.8.1/cxx/annotated.


http://www.panda3d.org/manual/index.php/Getting_Started_on_OSX

http://www.panda3d.org/manual/index.php/Getting_Started_on_OSX

http://www.panda3d.org/manual/index.php/Installing_Panda3D_in_Windows

http://www.panda3d.org/manual/index.php/Installing_Panda3D_in_Windows

http://www.panda3d.org/forums/index.php

http://www.panda3d.org/manual/index.php/Main_Page

http://www.panda3d.org/reference/1.8.1/cxx/annotated

http://www.panda3d.org/reference/1.8.1/cxx/annotated


FCG Lab04: Introduction to Panda3Dprojects.i-ctm.eu/sites/default/files/Lab_04_0.pdf · Where? .egg...

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