Hey
I’m currently porting a shadow system from Xbox 360 to DirectX 11. As a reference we want code with the same functionality to run on DirectX. The problem is that I can’t get the bilinear pcf interpolation to work properly. I tried many variants of the code but didn’t reach a satisfying result. This is how the code stands atm:
float4 vFrac;

// Clamp the lookup coord so they will be in complete sync with the bilinear weights
vecFrac.xy = modf((vShadowCoord.xy) * float2(768.0f, 768.0f), vShadowCoord.xy);
vShadowCoord.xy /= float2(768.0f, 768.0f);

// Compute the bilinear weights
vecFrac.zw = float2(1.0f, 1.0f) - vecFrac.xy;
float4 vBilinearWeights = vecFrac.zxzx * vecFrac.wwyy;

float4 vSamples;

// Read the 4 neighbours
vSamples.x = shadowMap.Sample(pointSampler, offsetCoord.xy, int2( 0.0, 0.0 )).x;
vSamples.y = shadowMap.Sample(pointSampler, offsetCoord.xy, int2( 1.0, 0.0 )).x;
vSamples.z = shadowMap.Sample(pointSampler, offsetCoord.xy, int2( 0.0, 1.0 )).x;
vSamples.w = shadowMap.Sample(pointSampler, offsetCoord.xy, int2( 1.0, 1.0 )).x;

// Compute the depth comparision for each tap
vShadowCoord.z -= 0.001f;
vSamples = step(vShadowCoord.zzzz, vSamples);

// The result
float shadow = dot(vSamples, vecBilinearWeights);
If I can get this to work I can increase the number of taps and implement other filters as well. Hardware accelerated pcf([font=courier new,courier,monospace]SampleCmpLevelZero[/font]) works fine and I don’t think there’s any wrong with the texture resource.

Does anybody know how I can implement proper bilinear texture filtering on DirectX 11 without using [font=courier new,courier,monospace]SampleCmpLevelZero[/font]? The artefacts I experience are sharp edges where the “interpolation” seems to start sudden. As the camera moves around the penumbra flickers like the sampling was dependent on the viewing angle.


Cheers

This is what it looks like

Hello.

I do mine like this.

[size="2"]static const float SMAP_SIZE = 2048.0f;//size of shadow texture
[size="2"]static const float SMAP_DX = 1.0f / SMAP_SIZE;

[size="2"]// Sample shadow map to get nearest depth to light.
[size="2"]float s0 = ShadowMap.Sample(ShadowSam, projTex.xy).r;
[size="2"]float s1 = ShadowMap.Sample(ShadowSam, projTex.xy + float2(SMAP_DX, 0)).r;
[size="2"]float s2 = ShadowMap.Sample(ShadowSam, projTex.xy + float2(0, SMAP_DX)).r;
[size="2"]float s3 = ShadowMap.Sample(ShadowSam, projTex.xy + float2(SMAP_DX, SMAP_DX)).r;

[size="2"]whats casting the shadow in the image if its a raised clif then you may need to filter the vertice heights a bit to smooth them out.