Fixed erroneous clear of photon counter if mixed lights are used;

Improved hitSphere function

Author: SirKero

Source/RenderPasses/ReSTIR_FG_Lite/GenerateInitialSamples.rt.slang

@@ -48,11 +48,7 @@ struct RayPayload
 bool hitSphere(const float3 center, const float radius, const float3 p)
 {
     float3 radiusTest = p - center;
-    radiusTest = radiusTest * radiusTest;
-    float radiusTestF = radiusTest.x + radiusTest.y + radiusTest.z;
-    if (radiusTestF < radius * radius)
-        return true;
-    return false;
+    return dot(radiusTest, radiusTest) < radius * radius;
 }
 
 /*  Collects all photons in a radius and estimates radiance.

Source/RenderPasses/ReSTIR_FG_Lite/ReSTIR_FG_Lite.cpp

@@ -259,6 +259,9 @@ void ReSTIR_FG_Lite::execute(RenderContext* pRenderContext, const RenderData& re
 
     mpRTXDI->beginFrame(pRenderContext, mScreenRes);
 
+    //Clear Photon Counter before tracing the Photons for this frame
+    pRenderContext->clearUAV(mpPhotonCounter->getUAV().get(), uint4(0));
+
     //Trace Photons. Up to two passes may be executed, depending on the light types in the scene
     //(one for emissive triangles and one for analytic point/spot lights)
     tracePhotonsPass(pRenderContext, renderData, !mMixedLights && mHasAnalyticLights, !mMixedLights && mPhotonAnalyticRatio > 0);
@@ -432,9 +435,6 @@ void ReSTIR_FG_Lite::tracePhotonsPass(RenderContext* pRenderContext, const Rende
 {
     FALCOR_PROFILE(pRenderContext, "TracePhotons");
 
-    //Clear Photon Counter
-    pRenderContext->clearUAV(mpPhotonCounter->getUAV().get(), uint4(0));
-
     // Init Shader
     if (!mTracePhotonPass.pProgram)
     {