Fix Spot Light

src/Shaders/ShadersInclude/pbrLightFunctions.fx

@@ -18,12 +18,11 @@ float computeDistanceLightFalloff(vec3 lightOffset, float lightDistanceSquared,
     return lightDistanceFalloff;
 }
 
-float computeDirectionalLightFalloff(vec3 lightDirection, vec3 directionToLightCenterW, float lightAngle, float exponent)
+float computeDirectionalLightFalloff(vec3 lightDirection, vec3 directionToLightCenterW, float cosHalfAngle, float exponent)
 {
     float falloff = 0.0;
     
     #ifdef USEPHYSICALLIGHTFALLOFF
-        float cosHalfAngle = cos(lightAngle * 0.5);
         const float kMinusLog2ConeAngleIntensityRatio = 6.64385618977; // -log2(0.01)
 
         // Calculate a Spherical Gaussian (von Mises-Fisher distribution, not angle-based Gaussian) such that the peak is in the light direction,