Light Pre-Pass Renderer

1. Geometry Pass
   Depth(xy), Normal(xy) Geometry Buffer(이하 G-Buffer) 저장
2. Light Properties Pass
   아래 최종 색상 식에 미리 계산된 항목을 Light Buffer(이하 L-Buffer)
   최종 색상 = Ambient + Shadow * Att * (N.L * diffuseColor * diffuseIntensity * diffuseLightColor + R.V^n * specularColor * specularIntensity * specularLightColor )
   
   Light Properties
   - N.L
   - LightColor (Diffuse, Specular)
   - R.V^n
   - Attenuation
   
   Light Texture(A8R8G8B8 format)
   - Channel 1 : diffuseLightColor.r * N.L * Att
   - Channel 2 : diffuseLightColor.g * N.L * Att
   - Channel 3 : diffuseLightColor.b * N.L * Att
   - Channel 4 : R.V^n * N.L *Att
   
   아래는 관련 Shader Code 입니다.
   

   half4 ps_main( PS_INPUT Input ) : COLOR
   {
   half4 G_Buffer = tex2D( G_Buffer, Input.texCoord );

   // Compute pixel position
   half Depth = UnpackFloat16( G_Buffer.zw );
   float3 PixelPos = normalize(Input.EyeScreenRay.xyz) * Depth;

   // Compute normal
   half3 Normal;
   Normal.xy = G_Buffer.xy*2-1;
   Normal.z = -sqrt(1-dot(Normal.xy,Normal.xy));

   // Computes light attenuation and direction
   float3 LightDir = (Input.LightPos – PixelPos)*InvSqrLightRange;
   half Attenuation = saturate(1-dot(LightDir / LightAttenuation_0, LightDir / LightAttenuation_0));
   LightDir = normalize(LightDir);

   // R.V == Phong
   float specular = pow(saturate(dot(reflect(normalize(-float3(0.0, 1.0, 0.0)), Normal), LightDir)), SpecularPower_0);

   float NL = dot(LightDir, Normal)*Attenuation;
   
   return float4(DiffuseLightColor_0.x*NL, DiffuseLightColor_0.y*NL, DiffuseLightColor_0.z*NL, specular * NL);
   }
   
   
   

3. Geometry-2 Pass
   G-Buffer와 L-Buffer에 값을 가지고 최종 색상을 계산
   
   아래는 관련 Shader Code입니다.
   

   float4 ps_main( PS_INPUT Input ) : COLOR0

   {
   float4 Light = tex2D( Light_Buffer, Input.texCoord );
   float3 NLATTColor = float3(Light.x, Light.y, Light.z);
   float3 Lighting = NLATTColor + Light.www;

   return float4(Lighting, 1.0f);
   }

   
   
4. Forward Rendering
   Translucency Objects Rendering(back to front)