Added max( value, 0.0 ) to schlick computation. Should fix #4366 and #4454.

src/renderers/shaders/ShaderChunk.js

@@ -842,7 +842,7 @@ THREE.ShaderChunk = {
 
 				"float specularNormalization = ( shininess + 2.0001 ) / 8.0;",
 
-				"vec3 schlick = specular + vec3( 1.0 - specular ) * pow( 1.0 - dot( lVector, pointHalfVector ), 5.0 );",
+				"vec3 schlick = specular + vec3( 1.0 - specular ) * pow( max( 1.0 - dot( lVector, pointHalfVector ), 0.0 ), 5.0 );",
 				"pointSpecular += schlick * pointLightColor[ i ] * pointSpecularWeight * pointDiffuseWeight * lDistance * specularNormalization;",
 
 			"}",
@@ -900,7 +900,7 @@ THREE.ShaderChunk = {
 
 					"float specularNormalization = ( shininess + 2.0001 ) / 8.0;",
 
-					"vec3 schlick = specular + vec3( 1.0 - specular ) * pow( 1.0 - dot( lVector, spotHalfVector ), 5.0 );",
+					"vec3 schlick = specular + vec3( 1.0 - specular ) * pow( max( 1.0 - dot( lVector, spotHalfVector ), 0.0 ), 5.0 );",
 					"spotSpecular += schlick * spotLightColor[ i ] * spotSpecularWeight * spotDiffuseWeight * lDistance * specularNormalization * spotEffect;",
 
 				"}",
@@ -969,7 +969,7 @@ THREE.ShaderChunk = {
 
 				//"dirSpecular += specular * directionalLightColor[ i ] * dirSpecularWeight * dirDiffuseWeight * specularNormalization * fresnel;",
 
-				"vec3 schlick = specular + vec3( 1.0 - specular ) * pow( 1.0 - dot( dirVector, dirHalfVector ), 5.0 );",
+				"vec3 schlick = specular + vec3( 1.0 - specular ) * pow( max( 1.0 - dot( dirVector, dirHalfVector ), 0.0 ), 5.0 );",
 				"dirSpecular += schlick * directionalLightColor[ i ] * dirSpecularWeight * dirDiffuseWeight * specularNormalization;",
 
 
@@ -1016,8 +1016,8 @@ THREE.ShaderChunk = {
 
 				"float specularNormalization = ( shininess + 2.0001 ) / 8.0;",
 
-				"vec3 schlickSky = specular + vec3( 1.0 - specular ) * pow( 1.0 - dot( lVector, hemiHalfVectorSky ), 5.0 );",
-				"vec3 schlickGround = specular + vec3( 1.0 - specular ) * pow( 1.0 - dot( lVectorGround, hemiHalfVectorGround ), 5.0 );",
+				"vec3 schlickSky = specular + vec3( 1.0 - specular ) * pow( max( 1.0 - dot( lVector, hemiHalfVectorSky ), 0.0 ), 5.0 );",
+				"vec3 schlickGround = specular + vec3( 1.0 - specular ) * pow( max( 1.0 - dot( lVectorGround, hemiHalfVectorGround ), 0.0 ), 5.0 );",
 				"hemiSpecular += hemiColor * specularNormalization * ( schlickSky * hemiSpecularWeightSky * max( dotProduct, 0.0 ) + schlickGround * hemiSpecularWeightGround * max( dotProductGround, 0.0 ) );",
 
 			"}",