float DoPCF(sampler2D sMap,float4 vShadowTexCoord,int iSqrtSamples,float fBias)
{
	float fShadowTerm = 0.0f;  
	float fRadius = (iSqrtSamples - 1.0f) / 2;

	for (float y = -fRadius; y <= fRadius; y++)
	{
		for (float x = -fRadius; x <= fRadius; x++)
		{
			float2 vOffset = float2(x,y)/pssm_res_var;
			float fDepth = tex2Dlod(sMap, float4(vShadowTexCoord.xy + vOffset, 0.0f, 0.0f)).x;
			float fSample = (vShadowTexCoord.z < fDepth + fBias);
			
			float xWeight = 1, yWeight = 1;
			if (x == -fRadius) 
				xWeight = 1 - frac(vShadowTexCoord.x * pssm_res_var);
			else if (x == fRadius)
				xWeight = frac(vShadowTexCoord.x * pssm_res_var);
			
			if (y == -fRadius)
				yWeight = 1 - frac(vShadowTexCoord.y * pssm_res_var);
			else if (y == fRadius)
				yWeight = frac(vShadowTexCoord.y * pssm_res_var);
			
			fShadowTerm += fSample * xWeight * yWeight;
		}											
	}		
	
	return fShadowTerm / (iSqrtSamples * iSqrtSamples);
}