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struct Light
{
float4 color; // and radius
float4 position; // and -cos(angle)
float4 direction; // and falloff clamp
};
float3 DoDirLight(Light L, float3 N)
{
float l = max(0.0, dot(N, -L.direction.xyz));
return l*L.color.xyz;
}
float3 DoDirLightSpec(Light L, float3 N, float3 V, float power)
{
return pow(saturate(dot(N, normalize(V + -L.direction.xyz))), power)*L.color.xyz;
}
float3 DoPointLight(Light L, float3 V, float3 N)
{
// As on PS2
float3 dir = V - L.position.xyz;
float dist = length(dir);
float atten = max(0.0, (1.0 - dist/L.color.w));
float l = max(0.0, dot(N, -normalize(dir)));
return l*L.color.xyz*atten;
}
float3 DoSpotLight(Light L, float3 V, float3 N)
{
// As on PS2
float3 dir = V - L.position.xyz;
float dist = length(dir);
float atten = max(0.0, (1.0 - dist/L.color.w));
dir /= dist;
float l = max(0.0, dot(N, -dir));
float pcos = dot(dir, L.direction.xyz); // cos to point
float ccos = -L.position.w; // cos of cone
float falloff = (pcos-ccos)/(1.0-ccos);
if(falloff < 0) // outside of cone
l = 0;
l *= max(falloff, L.direction.w); // falloff clamp
return l*L.color.xyz*atten;
}
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