Disable Atmospheric Scattering when Scene Lighting is Disabled (#6328)

* Disable atmospheric scattering for matcap debug lighting mode

* Changelog

Co-authored-by: sebastienlagarde <sebastien@unity3d.com>

Author: johnpars

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

@@ -38,6 +38,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - 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.
+- Fixed atmospheric scattering being incorrectly enabled when scene lighting is disabled.
 
 ### Changed
 - Optimizations for the physically based depth of field.

com.unity.render-pipelines.high-definition/Runtime/Lighting/AtmosphericScattering/AtmosphericScattering.hlsl

@@ -257,7 +257,7 @@ void EvaluateAtmosphericScattering(PositionInputs posInput, float3 V, out float3
 
 #ifdef DEBUG_DISPLAY
     // Don't sample atmospheric scattering when lighting debug more are enabled so fog is not visible
-    if (_DebugLightingMode >= DEBUGLIGHTINGMODE_DIFFUSE_LIGHTING && _DebugLightingMode <= DEBUGLIGHTINGMODE_EMISSIVE_LIGHTING)
+    if (_DebugLightingMode == DEBUGLIGHTINGMODE_MATCAP_VIEW || (_DebugLightingMode >= DEBUGLIGHTINGMODE_DIFFUSE_LIGHTING && _DebugLightingMode <= DEBUGLIGHTINGMODE_EMISSIVE_LIGHTING))
         return;
 
     if (_DebugShadowMapMode == SHADOWMAPDEBUGMODE_SINGLE_SHADOW || _DebugLightingMode == DEBUGLIGHTINGMODE_LUX_METER || _DebugLightingMode == DEBUGLIGHTINGMODE_LUMINANCE_METER)