Proper area light NaN fix (#4220)

FrancescoC-unity · sebastienlagarde · web-flow · commit 171f03b34a98 · 2021-04-21T00:45:21.000+02:00
* Proper fix

* changelog

Co-authored-by: sebastienlagarde &lt;sebastien@unity3d.com&gt;
diff --git a/com.unity.render-pipelines.core/ShaderLibrary/AreaLighting.hlsl b/com.unity.render-pipelines.core/ShaderLibrary/AreaLighting.hlsl
@@ -21,7 +21,8 @@ real3 ComputeEdgeFactor(real3 V1, real3 V2)
     if (V1oV2 < 0)
     {
         // Undo range reduction.
-        y = PI * rsqrt(saturate(1 - V1oV2 * V1oV2)) - y;
+        const float epsilon = 1e-5f;
+        y = PI * rsqrt(max(epsilon, saturate(1 - V1oV2 * V1oV2))) - y;
     }
 
     return V1xV2 * y;
diff --git a/com.unity.render-pipelines.high-definition/CHANGELOG.md b/com.unity.render-pipelines.high-definition/CHANGELOG.md
@@ -153,6 +153,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - Fixed global Settings ignore the path set via Fix All in HDRP wizard (case 1327978)
 - Fixed GBuffer clear option in FrameSettings not working
 - Fixed usage of Panini Projection with floating point HDRP and Post Processing color buffers.
+- Fixed a NaN generating in Area light code.
 
 ### Changed
 - Changed Window/Render Pipeline/HD Render Pipeline Wizard to Window/Rendering/HDRP Wizard

Original file line number	Diff line number	Diff line change
`@@ -21,7 +21,8 @@ real3 ComputeEdgeFactor(real3 V1, real3 V2)`
`21`	`21`	`if (V1oV2 < 0)`
`22`	`22`	`{`
`23`	`23`	`// Undo range reduction.`
`24`		`- y = PI * rsqrt(saturate(1 - V1oV2 * V1oV2)) - y;`
	`24`	`+ const float epsilon = 1e-5f;`
	`25`	`+ y = PI * rsqrt(max(epsilon, saturate(1 - V1oV2 * V1oV2))) - y;`
`25`	`26`	`}`
`26`	`27`
`27`	`28`	`return V1xV2 * y;`