// This is C7E4f_refraction from "The Cg Tutorial" (Addison-Wesley, ISBN
// 0321194969) by Randima Fernando and Mark J. Kilgard.  See page 188.

void C7E4f_refraction(float2 texCoord : TEXCOORD0,
                      float3 T        : TEXCOORD1,

                  out float4 color : COLOR,

              uniform float       transmittance,
              uniform sampler2D   decalMap,
              uniform samplerCUBE environmentMap)
{
  // Fetch the decal base color
  float4 decalColor = tex2D(decalMap, texCoord);

  // Fetch refracted environment color
  float4 refractedColor = texCUBE(environmentMap, T);

  // Compute the final color
  color = lerp(decalColor, refractedColor, transmittance);
}