void main
(
  float2 iTexCoord0 : TEXCOORD0,
  float2 iTexCoord1 : TEXCOORD1,
  float2 iTexCoord2 : TEXCOORD2,
  float2 iTexCoord3 : TEXCOORD3,
 
  out float4 oColor : COLOR,
 
  uniform sampler2D covMap,
  uniform sampler2D splat1,
  uniform sampler2D splat2,
  uniform sampler2D splat3
) 
{
  float3 cov = tex2D(covMap, iTexCoord0).rgb;
 
  oColor = tex2D(splat1, iTexCoord1) * cov.x
          + tex2D(splat2, iTexCoord2) * cov.y
          + tex2D(splat3, iTexCoord3) * cov.z;
}