From 9683222ce7af9a0cc86fe2335e9b6e9fc68b4e4f Mon Sep 17 00:00:00 2001 From: Chris Santora Date: Sun, 16 May 2021 12:52:27 -0700 Subject: [PATCH] Fixed a pre-existing bug where normals could be length 0. --- Gems/Atom/RPI/Assets/ShaderLib/Atom/RPI/TangentSpace.azsli | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/Gems/Atom/RPI/Assets/ShaderLib/Atom/RPI/TangentSpace.azsli b/Gems/Atom/RPI/Assets/ShaderLib/Atom/RPI/TangentSpace.azsli index 13e3c652db..6e0209eb3e 100644 --- a/Gems/Atom/RPI/Assets/ShaderLib/Atom/RPI/TangentSpace.azsli +++ b/Gems/Atom/RPI/Assets/ShaderLib/Atom/RPI/TangentSpace.azsli @@ -52,6 +52,12 @@ float3 GetTangentSpaceNormal_Unnormalized(float2 normalMapSample, float normalSt // The image build pipeline drops the B channel so we have to reconstruct it here. surfaceNormal.z = sqrt(1 - dot(surfaceNormal.xy, surfaceNormal.xy)); + // Don't allow z to be zero just in case normalStrength approaches 0, to avoid a 0-length normal. + // It doesn't make sense anyway to have a surface with a normal map completely tangential. + // This also addresses the possibility of z being NaN, in the case where x^2+y^2 > 1, so we don't need to call saturate in the sqrt operation above. + // (Note this edge case would be particularly evident in multilayer material types, where the normal map is masked out using normalStrength). + surfaceNormal.z = max(surfaceNormal.z, 0.01); + surfaceNormal.xy *= normalStrength; return surfaceNormal;