PCSS problem

Graphics and GPU Programming Programming

Started by Aqua Costa March 08, 2011 12:32 PM

0 comments, last by Aqua Costa 13 years, 1 month ago

Aqua Costa

3,705

Author

March 08, 2011 12:32 PM

Ive implemented CSM with PCSS but there is a problem with it:

I still have some improvements to do but I wanted to fix this error first...

Shader code:

SHADOW_EPSILON = 0.003f
SMAP_DX = 1.0f / 1024.0f;



float4 positionWS = float4(gEyePosW + pIn.viewRay * depth, 1.0f);



	positionLightHS = mul(positionWS, gLightView);



	for(int x = 0; x < 5; x++)

	{

		if(depth * 10000 <= gCascadesEnd[x])

		{

			positionLightHS = mul(positionLightHS, gLightProj[x]);

			positionLightHS.xyz /= positionLightHS.w;

			positionLightHS.xy = positionLightHS.xy * float2(0.5f, -0.5f) + float2(0.5f, 0.5f);

			positionLightHS.x /= 4;

			float2 cascadeOffset = float2((x/4.0f), 0.0f);

			positionLightHS.xy  += cascadeOffset;



			break;

		}

	}



	float depthS = positionLightHS.z;



	// Sample shadow map to get nearest depth to light.

	float s0 = gShadowMap.Sample(gTriPointSam, positionLightHS.xy).r;

	float s1 = gShadowMap.Sample(gTriPointSam, positionLightHS.xy + float2(SMAP_DX, 0)).r; 

	float s2 = gShadowMap.Sample(gTriPointSam, positionLightHS + float2(0, SMAP_DX)).r;

	float s3 = gShadowMap.Sample(gTriPointSam, positionLightHS.xy + float2(SMAP_DX, SMAP_DX)).r;

	float s4 = gShadowMap.Sample(gTriPointSam, positionLightHS.xy + float2(-SMAP_DX, 0)).r; 

	float s5 = gShadowMap.Sample(gTriPointSam, positionLightHS + float2(0, -SMAP_DX)).r;

	float s6 = gShadowMap.Sample(gTriPointSam, positionLightHS.xy + float2(-SMAP_DX, SMAP_DX)).r;

	float s7 = gShadowMap.Sample(gTriPointSam, positionLightHS.xy + float2(SMAP_DX, -SMAP_DX)).r;

	float s8 = gShadowMap.Sample(gTriPointSam, positionLightHS.xy + float2(-SMAP_DX, -SMAP_DX)).r;



	// Is the pixel depth <= shadow map value?

	float result0 = depthS <= s0 + SHADOW_EPSILON;

	float result1 = depthS <= s1 + SHADOW_EPSILON;

	float result2 = depthS <= s2 + SHADOW_EPSILON;

	float result3 = depthS <= s3 + SHADOW_EPSILON;

	float result4 = depthS <= s4 + SHADOW_EPSILON;

	float result5 = depthS <= s5 + SHADOW_EPSILON;

	float result6 = depthS <= s6 + SHADOW_EPSILON;

	float result7 = depthS <= s7 + SHADOW_EPSILON;

	float result8 = depthS <= s8 + SHADOW_EPSILON;

	shadowFactor = (result0 + result1 + result2 + result3 + result4 + result5 + result6 + result7 + result8) / 9;

Any idead about what might be causing that aliasing?

Aqua Costa

3,705

Author

March 08, 2011 10:35 PM

Well I fixed it with a little change in the shader...

Since I'm using a cascaded shadow map with 4 cascades, when I sample the shadow map I must divide the shadow map texel size by the number of cascades, but just on the x coordinate...
So:



	float s0 = gShadowMap.Sample(gTriPointSam, positionLightHS.xy).r;

	float s1 = gShadowMap.Sample(gTriPointSam, positionLightHS.xy + float2(SMAP_DX/4, 0)).r; 

	float s2 = gShadowMap.Sample(gTriPointSam, positionLightHS + float2(0, SMAP_DX)).r;

	float s3 = gShadowMap.Sample(gTriPointSam, positionLightHS.xy + float2(SMAP_DX/4, SMAP_DX)).r;

	float s4 = gShadowMap.Sample(gTriPointSam, positionLightHS.xy + float2(-SMAP_DX/4, 0)).r; 

	float s5 = gShadowMap.Sample(gTriPointSam, positionLightHS + float2(0, -SMAP_DX)).r;

	float s6 = gShadowMap.Sample(gTriPointSam, positionLightHS.xy + float2(-SMAP_DX/4, SMAP_DX)).r;

	float s7 = gShadowMap.Sample(gTriPointSam, positionLightHS.xy + float2(SMAP_DX/4, -SMAP_DX)).r;

	float s8 = gShadowMap.Sample(gTriPointSam, positionLightHS.xy + float2(-SMAP_DX/4, -SMAP_DX)).r;

Aqua Costa

3,705

Author

March 10, 2011 05:47 PM

Well I fixed it with a little change in the shader...

Since I'm using a cascaded shadow map with 4 cascades, when I sample the shadow map I must divide the shadow map texel size by the number of cascades, but just on the x coordinate...
So:
float s0 = gShadowMap.Sample(gTriPointSam, positionLightHS.xy).r; float s1 = gShadowMap.Sample(gTriPointSam, positionLightHS.xy + float2(SMAP_DX/4, 0)).r; float s2 = gShadowMap.Sample(gTriPointSam, positionLightHS + float2(0, SMAP_DX)).r; float s3 = gShadowMap.Sample(gTriPointSam, positionLightHS.xy + float2(SMAP_DX/4, SMAP_DX)).r; float s4 = gShadowMap.Sample(gTriPointSam, positionLightHS.xy + float2(-SMAP_DX/4, 0)).r; float s5 = gShadowMap.Sample(gTriPointSam, positionLightHS + float2(0, -SMAP_DX)).r; float s6 = gShadowMap.Sample(gTriPointSam, positionLightHS.xy + float2(-SMAP_DX/4, SMAP_DX)).r; float s7 = gShadowMap.Sample(gTriPointSam, positionLightHS.xy + float2(SMAP_DX/4, -SMAP_DX)).r; float s8 = gShadowMap.Sample(gTriPointSam, positionLightHS.xy + float2(-SMAP_DX/4, -SMAP_DX)).r;

PCSS problem

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