Vertex

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Vertex Pixel Shaders

• CPS124 Computer Graphics

Ferdinand Schober
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Shader History I

• 1995/1996 3dfx Voodoo 1 first mass market GPU,
  hw accelerated rasterization GLIDE API, 16bit
  buffers, texturing shading Quake using OpenGL!
• 1998 3dfx Voodoo 2 / Banshee AGP port, but no
  AGP texturing two texture units for single-pass
  multitexturing
• 1999 Nvidia Geforce 256 / Matrox G400 fixed
  function graphics pipeline (TL) first hardware
  OpenGL support DDR memory introduction bump
  mapping

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Shader History II

• 2000 3dfx Voodoo 3 / Nvidia Geforce
  2 multi-texturing unit, Year of Nvidia, per
  pixel shading, hardware transform clipping
  shading, full screen antialiasing
• 2001 Nvidia Geforce 3 programmable TL
• 2002 Nvidia Geforce 4Ti / DirectX 9.0 first
  full hardware/software shader support
• 2003 Nvidia Geforce FX / ATI Radeon
  9800XT 256-bit memory port, displacement
  mapping, 128-bit color precision, Ultra
  Shadow, AGP 8x

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Current Graphic Cards

• Geforce FX 5950 Ultra
• Graphics Core/Interface 256-bit
• Fill Rate 3.8 billion texels/sec.
• Vertices/sec. 356 million
• Textures per Pixel 16
• Pixel Shaders (2.0)/Vertex Shaders
• Supports OpenGL 1.5 / DX9.0
• UltraShadow, CineFX 2.0

Geforce FX Demo
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Current Graphic Cards II

• ATI Radeon 9800XT
• Graphics Core/Interface 256-bit
• Fill Rate 3.3 gpixels/sec.
• Vertices/sec. 412 million
• 2x/4x/6x full screen antialiasing
• Pixel Shaders (2.0)/Vertex Shaders
• Supports OpenGL 1.5 / DX9.0
• SmartShader, Truform 2.0
• Videoshader

ATI Radeon 9800XT Demo
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Pixel vs. Vertex Shaders

• Definition (wikipedia)

3D hardware previously used fixed-function
pipelines in which, for example, one was stuck
with the lighting model chosen by the hardware
vendor. Graphics hardware was able to do
transformation and lighting (TL for short) on
the card, but it was not flexible. A vertex
shader sidesteps the TL stage in the pipeline
and lets the user add on to it. Pixel shaders
operate after the geometry pipeline and before
final rasterization. They operate in parallel
with multitexturing to produce a final pixel
color and z-value for the final, rasterization
step in the graphics pipeline (where alpha
blending and depth testing occur).
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Shader Languages

• Different Standards
• Nvidia Cg ATI
  HSLS (DirectX 9) OpenGL GL2
• Provide high level language for assembler-based
  
• shading code. Use optimized (JIT) compilers to
• transform to highly efficient machine code.
• Winner yet undecided.

Example Shaders
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Small Example (Cg)

• Why Cg?
• Open source compiler
• Works with OpenGL DirectX
• C-like language
• can be used for multiple GPUs/Platforms

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Small Example (Cg) II
The program transforms an object-space position
for a vertex by a 4x4 matrix containing the
concatenation of the modeling, viewing, and
projection transforms. The resulting vector is
output as the clip-space position of the vertex.
The per-vertex color is scaled by a
floating-point parameter prior to output. Also,
two texture coordinate sets are passed through
unperturbed.

void simpleTransform(float4 objectPosition
POSITION, float4 color COLOR, float4 decalCoord
TEXCOORD0, float4 lightMapCoord
TEXCOORD1, out float4 clipPosition POSITION,
out float4 oColor COLOR, out float4 oDecalCoord
TEXCOORD0, out float4 oLightMapCoord
TEXCOORD1, uniform float brightness, uniform
float4x4 modelViewProjection) clipPosition
mul(modelViewProjection, objectPosition) oColor
brightness color oDecalCoord
decalCoord oLightMapCoord lightMapCoord
vs.1.1 mov oT0, v7 mov oT1, v8 dp4 oPos.x, c1,
v0 dp4 oPos.y, c2, v0 dp4 oPos.z, c3, v0 dp4
oPos.w, c4, v0 mul oD0, c0.x, v5
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Eye Candy

• And now some shader eye candy

• Radeon vertex shading/bump mapping demo
• HSLS demo
• Dynamic Fur
• Radeon 9700 demos
• ? More in cutting-edge games lecture

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Vertex Pixel Shaders

The End
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