Hi guys,

Right now I offset my shadowmap lookups with an array of constant values. I'm not sure if that's such a good idea since every pixel has the same sampling pattern.

I think the way to go is to fill a texture with random offset values but I don't know how to access them that way, what should I use for the uv values ?

I'm doing this now:

static const float2 Offsets[8] =
{
  float2(0.560991f, 0.741455f),
  ...
};
 
for(int i=0;i<8;i++){
  occluder=tex2D(ShadowMap,input.proj.xy+Offsets[i]*0.001f).x;
  sum += (occluder < receiver) ? 0 : 1;
}
shadow=sum/8;

I'd like a better way that isn't terribly complicated. Thanks a lot.

Thanks a lot, I switched to a Poisson disk for now. I will try out MJP's method tonight and see what happens.

Is there a way I can do adaptive sampling ? For example, if the samples are along the shadow edge I can take many more samples. I tried taking four samples and testing them but it didn't really work:

sum=0.0f;
 
occluder=tex2D(Sampler0,input.proj.xy+float2(0,1)*0.002f).x;
sum+=(occluder < receiver) ? 0.0f : 1.0f;
 
occluder=tex2D(Sampler0,input.proj.xy+float2(1,0)*0.002f).x;
sum+=(occluder < receiver) ? 0.0f : 1.0f;
 
occluder=tex2D(Sampler0,input.proj.xy+float2(0,-1)*0.002f).x;
sum+=(occluder < receiver) ? 0.0f : 1.0f;
 
occluder=tex2D(Sampler0,input.proj.xy+float2(-1,0)*0.002f).x;
sum+=(occluder < receiver) ? 0.0f : 1.0f;
 
if(sum == 0.0f){
 // all in shadow
 shadow=0.0f;
}
else if(sum == 4.0f){
 // all out of shadow
 shadow=1.0f;
}
else{
 // on penumbra
 // take lots of samples
}

Thanks again.

I'm trying to anti-alias the hard edges from my SSM setup, I don't really want soft shadows per se.

I average multiple samples offset by the Poisson values. I'm not sure if this is defined as PCF (I think it is),

I was thinking, if all the samples in the disk are in shadow there really isn't a need to samples so many, the average will be the same if I sample 2 or 200. So maybe I can do a test and take a large number of samples only where it's needed on the edges.

Thanks a lot for helping.

MJP, that's interesting. I'm going to do some research on Hi-Z because I'm not really sure what you mean. Thanks for helping.

PS - I was just reading (I think your) Position From Depth 3, it's very useful.