remove double application of flipNormal when double sided in the indirect irradiance calculation.

src/renderers/shaders/ShaderChunk/lights_pars.glsl

@@ -172,13 +172,11 @@ vec3 getAmbientLightIrradiance( const in vec3 ambientLightColor ) {
 
 	vec3 getLightProbeIndirectIrradiance( /*const in SpecularLightProbe specularLightProbe,*/ const in GeometricContext geometry, const in int maxMIPLevel ) {
 
-		#include <normal_flip>
-
 		vec3 worldNormal = inverseTransformDirection( geometry.normal, viewMatrix );
 
 		#ifdef ENVMAP_TYPE_CUBE
 
-			vec3 queryVec = flipNormal * vec3( flipEnvMap * worldNormal.x, worldNormal.yz );
+			vec3 queryVec = vec3( flipEnvMap * worldNormal.x, worldNormal.yz );
 
 			// TODO: replace with properly filtered cubemaps and access the irradiance LOD level, be it the last LOD level
 			// of a specular cubemap, or just the default level of a specially created irradiance cubemap.
@@ -198,7 +196,7 @@ vec3 getAmbientLightIrradiance( const in vec3 ambientLightColor ) {
 
 		#elif defined( ENVMAP_TYPE_CUBE_UV )
 
-			vec3 queryVec = flipNormal * vec3( flipEnvMap * worldNormal.x, worldNormal.yz );
+			vec3 queryVec = vec3( flipEnvMap * worldNormal.x, worldNormal.yz );
 			vec4 envMapColor = textureCubeUV( queryVec, 1.0 );
 
 		#else
@@ -237,15 +235,13 @@ vec3 getAmbientLightIrradiance( const in vec3 ambientLightColor ) {
 
 		#endif
 
-		#include <normal_flip>
-
 		reflectVec = inverseTransformDirection( reflectVec, viewMatrix );
 
 		float specularMIPLevel = getSpecularMIPLevel( blinnShininessExponent, maxMIPLevel );
 
 		#ifdef ENVMAP_TYPE_CUBE
 
-			vec3 queryReflectVec = flipNormal * vec3( flipEnvMap * reflectVec.x, reflectVec.yz );
+			vec3 queryReflectVec = vec3( flipEnvMap * reflectVec.x, reflectVec.yz );
 
 			#ifdef TEXTURE_LOD_EXT
 
@@ -261,14 +257,14 @@ vec3 getAmbientLightIrradiance( const in vec3 ambientLightColor ) {
 
 		#elif defined( ENVMAP_TYPE_CUBE_UV )
 
-			vec3 queryReflectVec = flipNormal * vec3( flipEnvMap * reflectVec.x, reflectVec.yz );
+			vec3 queryReflectVec = vec3( flipEnvMap * reflectVec.x, reflectVec.yz );
 			vec4 envMapColor = textureCubeUV(queryReflectVec, BlinnExponentToGGXRoughness(blinnShininessExponent));
 
 		#elif defined( ENVMAP_TYPE_EQUIREC )
 
 			vec2 sampleUV;
-			sampleUV.y = saturate( flipNormal * reflectVec.y * 0.5 + 0.5 );
-			sampleUV.x = atan( flipNormal * reflectVec.z, flipNormal * reflectVec.x ) * RECIPROCAL_PI2 + 0.5;
+			sampleUV.y = saturate( reflectVec.y * 0.5 + 0.5 );
+			sampleUV.x = atan( reflectVec.z, reflectVec.x ) * RECIPROCAL_PI2 + 0.5;
 
 			#ifdef TEXTURE_LOD_EXT
 
@@ -284,7 +280,7 @@ vec3 getAmbientLightIrradiance( const in vec3 ambientLightColor ) {
 
 		#elif defined( ENVMAP_TYPE_SPHERE )
 
-			vec3 reflectView = flipNormal * normalize( ( viewMatrix * vec4( reflectVec, 0.0 ) ).xyz + vec3( 0.0,0.0,1.0 ) );
+			vec3 reflectView = normalize( ( viewMatrix * vec4( reflectVec, 0.0 ) ).xyz + vec3( 0.0,0.0,1.0 ) );
 
 			#ifdef TEXTURE_LOD_EXT