<s5>Æliens</s5> -- slide(s)

4 generations of GPU

Before the introduction of the GPU, there only existed very expensive specialized hardware such as the machines from SGI.
The first generation of GPU, including NVIDIA TNT2, ATI Rage and 3dfx Voodoo3, only supported rasterizing pre-transformed triangles and some limited texture operations.
The second generation of GPUs, which were introduced around 1999, included the NVIDIA GeForce 2 and ATI Radeon 7500. They allowed for both 3D vertex transformations and some lighting, conformant with OpenGL and DirectX 7.
The tird generation GPUs, including NVIDIA GeForce 3, Microsoft Xbox and ATI Radeon 8500, included both powerful vertex processing capabilities and some pixel-based configuration operations, exceeding those of OpenGL and DirectX 7.
Finally, the fourth generation of GPUs, such as the NVIDIA GeForce FX and ATI Radeon 9700, allow for both complex vertex and pixel operations.

graphics pipeline

vertex transformation -- apply world, view, projection transforms
assembly and rasterization -- combine, clip and determine pixel locations
fragment texturing and coloring -- determine pixel colors
raster operations -- update pixel values

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A simple morphing shader in ViP, see section 4.3.

HLSL declarations


  texture tex;
  float4x4 wvp;	// World * View * Projection matrix
  
  sampler tex_sampler = sampler_state
  {
      texture = /;    
  };

vertex shader data flow


  struct vsinput {
      float4 position : POSITION; 
      float3 normal : NORMAL; 
      float2 uv : TEXCOORD0;
  };
  struct vsoutput {
      float4 position   : POSITION;   // vertex position 
      float4 color    : COLOR0;     // vertex diffuse color
      float2 uv  : TEXCOORD0;  // vertex texture coords 
  };

vertex shader


  vsoutput vs_id( vsinput vx ) {
      vsoutput vs;
    
      vs.position = mul(vx.position, wvp);
      vs.color = color;
      vs.uv = vx.uv; 
      
      return vs;    
  }

pixel shader


  struct psoutput
  {
      float4 color : COLOR0;  
  };
  
  
  psoutput ps_id( vsoutput vs ) 
  { 
      psoutput ps;
  
      ps.color = tex2D(tex_sampler, vs.uv) * vs.color;
  
      return ps;
  }

technique selection


  technique render_id
  {
      pass P0
      {          
          VertexShader = compile vs_1_1 vs_id();
          PixelShader  = compile ps_2_0 ps_id(); 
      }
  }

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Examples of Impasto, see examples -- impasto

morphing (vertex) shader


     float3 spherePos = normalize(vx.position.xyz);
     float3 cubePos = 0.9 * vx.position.xyz;
  
     float t = frac(speed * time);
     t = smoothstep(0, 0.5, t) - smoothstep(0.5, 1, t);
  
     // find the interpolation factor
     float lrp = lerpMin + (lerpMax - lerpMin) * t;
  
     // linearly interpolate the position and normal
     vx.position.xyz = lerp(spherePos, cubePos, lrp);
     vx.normal = lerp(sphereNormal, cubeNormal, lrp);
  
     // apply the transformations
     vs.position = mul(wvp, vx.position);

coloring (pixel) shader


      float4 x = tex2D(tex_sampler, vs.uv);
      if (x.r > x.g && x.r > x.b) { x.r *= xi; x.g *= xd; x.b *= xd; }
      else  if (x.g > x.r && x.g > x.b) { x.g *= xi; x.r *= xd; x.b *= xd; }
      else  if (x.b > x.r && x.b > x.g) { x.b *= xi; x.r *= xd; x.g *= xd; }
      ps.color = x;

Æliens

2009

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