Just a quick one (hopefully). I'm trying to use hardward PCF that's apparently built in later than dx9 so I'm updating some old shaders.

I was using:

distanceStoredInDepthMap = tex2D(ShadowMapSamplerHQ, lightSamplePos);    
                shadowCondition =  distanceStoredInDepthMap  <= (realDistanceToLight);    

                float lit = float(ShadowMapHQ.SampleCmpLevelZero(cmpSampler, lightSamplePos, realDistanceToLight));
                

distanceStoredInDepthMap = tex2D(ShadowMapSamplerHQ, lightSamplePos);	
shadowCondition =  distanceStoredInDepthMap  <= (realDistanceToLight);	

I'm trying update it to use the comparison method on the Texture2D object;

float lit = float(ShadowMapHQ.SampleCmpLevelZero(cmpSampler, lightSamplePos, realDistanceToLight));

But it's just returning 0. I've just left SamplerComparisonState as defaults.

Sorry if this is a dumb question.

Are you sure that cmpSampler has been setup correctly? You will have to configure it via the API. Use Renderdoc to double check

FWIW, hardware PCF is available in D3D9 but it's a bit messy. See: 

So essentially what i'm doing is correct with SampleCmpLevelZero is it? It compares whatever is at that texture coordinate with the float I pass in parameter 3 (using whatever samplercomparisionstate is have set)? Or have I misunderstood something else?