Fix for shadows disappearing when no dynamic shadow caster is available

com.unity.render-pipelines.high-definition/CHANGELOG.md

@@ -37,6 +37,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - Fixed nullref from debug menu in release build (case 1381556).
 - Fixed debug window reset.
 - Fixed camera bridge action in release build (case 1367866).
+- Fixed contact shadow disappearing when shadowmask is used and no non-static object is available.
 
 ### Changed
 - Optimizations for the physically based depth of field.

com.unity.render-pipelines.high-definition/Runtime/Lighting/Light/HDGpuLightsBuilder.LightLoop.cs

@@ -225,7 +225,8 @@ private void GetContactShadowMask(HDAdditionalLightData hdAdditionalLightData, B
                 return;
 
             // Evaluate the contact shadow index of this light
-            contactShadowMask = 1 << m_ContactShadowIndex++;
+            contactShadowMask = 1 << m_ContactShadowIndex;
+            m_ContactShadowIndex++; // Update the index for next light that will need to cast contact shadows.
 
             // If this light has ray traced contact shadow
             if (hdCamera.frameSettings.IsEnabled(FrameSettingsField.RayTracing) && hdAdditionalLightData.rayTraceContactShadow)

com.unity.render-pipelines.high-definition/Runtime/Lighting/Shadow/ContactShadows.compute

@@ -200,9 +200,9 @@ void DeferredContactShadow(uint2 groupThreadId : SV_GroupThreadID, uint2 groupId
         // Do the contact shadow for the directional light
         if (featureFlags & LIGHTFEATUREFLAGS_DIRECTIONAL)
         {
-            if (_DirectionalShadowIndex >= 0)
+            for (int i = 0; i < _DirectionalLightCount; ++i)
             {
-                DirectionalLightData light = _DirectionalLightDatas[_DirectionalShadowIndex];
+                DirectionalLightData light = _DirectionalLightDatas[i];
 
                 if (light.contactShadowMask != 0 && light.isRayTracedContactShadow == 0.0)
                 {
@@ -214,6 +214,7 @@ void DeferredContactShadow(uint2 groupThreadId : SV_GroupThreadID, uint2 groupId
                     // we take full bits at one multiplied by contact shadow and filter the bit at the contact shadow index.
                     contactShadowMask |= light.contactShadowMask * occluded;
                 }
+
             }
         }
 

com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/Raytracing/Shaders/Shadows/RayTracingContactShadow.raytrace

@@ -94,10 +94,9 @@ void RayGenContactShadows()
     uint contactShadowMask = 0;
     UnpackContactShadowData(_ContactShadowTextureUAV[COORD_TEXTURE2D_X(pixelCoord)], fade, contactShadowMask);
 
-    // Let's first process the directional shadow
-    if (_DirectionalShadowIndex >= 0)
+	for (int i = 0; i < _DirectionalLightCount; ++i)
     {
-        DirectionalLightData light = _DirectionalLightDatas[_DirectionalShadowIndex];
+        DirectionalLightData light = _DirectionalLightDatas[i];
 
         if (light.contactShadowMask != 0 && light.isRayTracedContactShadow == 1.0)
         {