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C-/C++-Quelltext

float4 PixScene( float2 Tex : TEXCOORD0,
                 float4 vPos : TEXCOORD1,
                 float3 vNormal : TEXCOORD2,
                 float4 vPosLight : TEXCOORD3 ) : COLOR
{
    float4 Diffuse;

    // vLight is the unit vector from the light to this pixel
    float3 vLight = normalize( float3( vPos - g_vLightPos ) );

    // Compute diffuse from the light
    if( dot( vLight, g_vLightDir ) > g_fCosTheta ) // Light must face the pixel (within Theta)
    {
        // Pixel is in lit area. Find out if it's
        // in shadow using 2x2 percentage closest filtering

        //transform from RT space to texture space.
        float2 ShadowTexC = 0.5 * vPosLight.xy / vPosLight.w + float2( 0.5, 0.5 );
        ShadowTexC.y = 1.0f - ShadowTexC.y;

        // transform to texel space
        float2 texelpos = SMAP_SIZE * ShadowTexC;
        
        // Determine the lerp amounts           
        float2 lerps = frac( texelpos );

        //read in bilerp stamp, doing the shadow checks
        float sourcevals[4];
        sourcevals[0] = (tex2D( g_samShadow, ShadowTexC ) + SHADOW_EPSILON < vPosLight.z / vPosLight.w)? 0.0f: 1.0f;  
        sourcevals[1] = (tex2D( g_samShadow, ShadowTexC + float2(1.0/SMAP_SIZE, 0) ) + SHADOW_EPSILON < vPosLight.z / vPosLight.w)? 0.0f: 1.0f;  
        sourcevals[2] = (tex2D( g_samShadow, ShadowTexC + float2(0, 1.0/SMAP_SIZE) ) + SHADOW_EPSILON < vPosLight.z / vPosLight.w)? 0.0f: 1.0f;  
        sourcevals[3] = (tex2D( g_samShadow, ShadowTexC + float2(1.0/SMAP_SIZE, 1.0/SMAP_SIZE) ) + SHADOW_EPSILON < vPosLight.z / vPosLight.w)? 0.0f: 1.0f;  
        
        // lerp between the shadow values to calculate our light amount
        float LightAmount = lerp( lerp( sourcevals[0], sourcevals[1], lerps.x ),
                                  lerp( sourcevals[2], sourcevals[3], lerps.x ),
                                  lerps.y );
        // Light it
        Diffuse = ( saturate( dot( -vLight, normalize( vNormal ) ) ) * LightAmount * ( 1 - g_vLightAmbient ) + g_vLightAmbient )
                  * g_vMaterial;
    } else
    {
        Diffuse = g_vLightAmbient * g_vMaterial;
    }

    return tex2D( g_samScene, Tex ) * Diffuse;
}