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Topics from Graphics 1

Image taken fromhttp://www.felixgers.de/teaching/game/game-modules-talk/GameEngineAndModules.html

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Synthetic Camera Model

Images copied from http://www.cs.unm.edu/~angel/BOOK/INTERACTIVE_COMPUTER_GRAPHICS/SIXTH_EDITION/ART/

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Camera Specification

Six degrees of freedom Position of center of lens (COP) Orientation

Lens – focal length Film size (h,w) Orientation of film plane

Images copied from http://www.cs.unm.edu/~angel/BOOK/INTERACTIVE_COMPUTER_GRAPHICS/SIXTH_EDITION/ART/

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LookAt

Images copied from http://www.cs.unm.edu/~angel/BOOK/INTERACTIVE_COMPUTER_GRAPHICS/SIXTH_EDITION/ART/

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PerspectiveFrustum: a truncated pyramid

Images copied from http://www.cs.unm.edu/~angel/BOOK/INTERACTIVE_COMPUTER_GRAPHICS/SIXTH_EDITION/ART/

and slightly modified

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Using Field of View

fovy – angle in up directionaspect = w/h

front plane

Images copied from http://www.cs.unm.edu/~angel/BOOK/INTERACTIVE_COMPUTER_GRAPHICS/SIXTH_EDITION/ART/

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Clipping

Just as a real camera cannot “see” the whole world, the virtual camera can only see part of the world or object space Objects that are not within this view volume are said

to be clipped out of the scene

Images copied from http://www.cs.unm.edu/~angel/BOOK/INTERACTIVE_COMPUTER_GRAPHICS/SIXTH_EDITION/ART/

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Projection Projection: from 3D objects to 2D image

Perspective projections: all projectors meet at the center of projection

Parallel (orthogonal) projection: projectors are parallel, center of projection is replaced by a direction of projection

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Orthogonal Viewing

Images copied from http://www.cs.unm.edu/~angel/BOOK/INTERACTIVE_COMPUTER_GRAPHICS/SIXTH_EDITION/ART/

and slightly modified

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Texture Mapping

Image copied fromhttp://blog.tartiflop.com/2008/11/first-steps-in-away3d-part-3-texture-mapping/

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A function f(u,v)=(x(u,v)

,y(u,v)

,z(u,v)

) defines the object position of each pixel in the texture, see this. The color of each pixelis the colorof the point(u,v) of thetexture.

Mapping a Texture

Images copied from http://www.cs.unm.edu/~angel/BOOK/INTERACTIVE_COMPUTER_GRAPHICS/SIXTH_EDITION/ART/

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Texture Mapping General Triangles

When the triangle does not fit properly on the texture, one has to use interpolation to determine the color associate with the a point on the object. This is done automatically by graphic systems. All one needs to give are the (u,v) coordinates of the vertices. For the upper triangle counterclockwise from lower left they are (0,0), (1,1), (0,1). The counterclockwise order is used in right hand coordinate systems, like Ogre and Opengl. DirectX and Unity uses a left hand system Most graphic systems will let one map textures to quadrilaterals, in that case the texture coordinate are (0,0), (1,0), (1,1), (0,1) counterclockwise from lower left.

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Texture Mapping and the Hardware

Vertex shadervertices

Fragment shaderimagerasterizer

Images and geometry flow through separate pipelines that join at the rasterizer “complex” textures do not affect geometric

complexity

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Planet Earth-Picture

Images copied from http://www.3dstudio-max.com/textures/images/earth.jpg

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Example-Planet Earth 3D

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Planet Earth-Mesh

Use Spherical Coordinates to determine the mesh coordinates

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Planet Earth-Mapping

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Meshes

A mesh of quadrilaterals as shown in the last slide or a mesh of triangles is used in graphics to draw surfaces. When textures are attached to the quadrilaterals or triangle the surface appears solid.

SeeOgre Mesh Class, Describing a mesh

Dynamically generating a mesh

for information onhow Ogre reads andstores meshes

Images copied from http://www.codesampler.com/d3dbook/chapter_05/chapter_05_files/image001.jpg

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Ogre Camera and Textures

Ogre camera class, http://www.ogre3d.org/docs/api/1.9/class_ogre_1_1_camera.html

Ogre Third Person Camerahttp://www.ogre3d.org/tikiwiki/tiki-index.php?page=Simple+3rd+person+camera

Ogre First Person Camerahttp://www.ogre3d.org/tikiwiki/Creating+a+simple+first-person+camera+system

Ogre Texturehttp://www.ogre3d.org/tikiwiki/-Texture

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Scene Graph

In unity each object has a transformation and can include other objects and meshes. Together these produce the scene graph for the scene.

Images copied from http://wiki.jmonkeyengine.org/doku.php/jme3:the_scene_graph