Part 1: Foundations

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• Part 1 Foundations
• Part 2 Classical 3D CG
• Part 3 Realtime Rendering
• Part 4 Control of Objects
• Part 5 2D Technology
• Part 5 Software Technology

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• PART 2 Classical 3D
• 6. Classic Polygon Rendering
• 7. Classic Mapping
• 8. Anti-aliasing

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Chap 6. Classical Polygon MeshRendering
Technology

• 6-1. Coordinate Spaces and Geometric Operations
• 6-2. Operations carried out in View Space
• 6-3. Algorithmic Operations in the Graphics
  Pipeline
• 6-4. Rendering Examples

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• We shall study the graphics pipeline
• to use the game engine effectively
• to develop the game engine

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Rendering pipeline
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6-3-2. Lighting

• Lighting model

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• Three shading methods
• 1) Flat shading
• 2) Gouraud shading
• 3) Phong shading

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• For each vertex,
• (X, Y, Z)
• I (R, G, B) or N (Nx, Ny, Nz)

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6-1. Coords and Geometric Ops

• Local (modeling) coords
• Object creation, modification, animation
• World coords
• Layout objects, lights
• Compute the vertex attributes
• (normal vector, color, (u,v), )
• Camera (eye, view) coords
• Normalization
• Clipping

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Case 1Camera transform is known
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• Example
• Mc R(90) T(d)
• C I
• C C T(-d)
• C C R(-90)
• glMatrixMode(GL_MODELVIEW)
• glLoadIdentity ()
• glTranslatef (0.0, 0.0, -d)
• gkRotatef (-90.0, 0.0, 1.0, 0.0)

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Case 2Direct camera placement
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• i) Specify the view reference point (C)
• ii) Specify the view plane normal, n
• iii) Specify the view-up vector (v)
• iv) Compute the up-vector, v
• v) Compute the side vector, u
• Weve got the viewing coordinate system, u-v-n.
• Practice pp. 207.

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• Typically,
• v (0, 1, 0)
• v v (v n) n
• u - v x n

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Case 3 by looking-at the target

• C (eyeX, eyeY, eyeZ)
• n (atX, atY, atZ) - C
• v v
• u n x v
• gluLookAt (eye, at, v)

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model-view matrix
Mo
Mc
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model-view matrix
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perspective projection
Let d be the focal length.
top view
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perspective projection

• not affine,
• not linear,
• irreversible.

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making non-linear linear
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Perspective Division
Projection

• Model-view

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2D object in the screen coordinates (normalized de
vice coord)
3D object in the camera coordinates
perspective projection
3D object in the distorted coordinates (clip
coordinates)
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model-view transform
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clipping

• View frustum clipping
• Back-face clipping

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• At the end of geometry processing
• For each vertex,
• (X, Y, Z)
• I (R, G, B) or N (Nx, Ny, Nz)

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• Hidden surface removal ? z-buffer algorithm
• Shading
• Rasterization
• occur simultaneously.

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• At the end of pixel processing,
• For each pixel,
• I (R, G, B) in FB
• Zmin in Z-buffer