Shader.cg

struct VIn
{
    float4 p  : POSITION;
    float2 uv : TEXCOORD0;
};

struct VOut
{
    float4 p  : POSITION;
    float  c  : CLP0;
    float2 uv : TEXCOORD0;
};

struct PIn
{
    float2 uv : TEXCOORD0;
};

VOut LightVS(VIn IN,
    uniform float4x4 wMat,
    uniform float4x4 wvpMat,
    uniform float4 clipPlane)
{
    VOut OUT;
    OUT.p = mul(wvpMat, IN.p);
    OUT.c = dot(mul(wMat, IN.p), clipPlane);
    OUT.uv = IN.uv;
    return OUT;
}

float4 LightPS(PIn IN,
    uniform float4 colorPrimary,
    uniform float4 colorSecondary,
    uniform float4 colorOptional,
    uniform sampler2D diffuseMap : TEXUNIT0):COLOR
{
    float4 colorDiffuse = tex2D(diffuseMap, IN.uv);
    float3 colorBlack = float3(0, 0, 0);
    float3 primaryContrib = lerp(colorBlack, colorPrimary, colorDiffuse.r/127);
    float3 secondaryContrib = lerp(colorBlack, colorSecondary, colorDiffuse.g/127);
    float3 optionalContrib = lerp(colorBlack, colorOptional, colorDiffuse.b/127);
    float3 finalContrib = primaryContrib + secondaryContrib + optionalContrib;
    return float4(finalContrib, colorDiffuse.a);
}