Testing the impact of normalization of transformed normals in vertex shaders (phong, normal, normalmap, skin simple).

It seems the effects on performance are minimal: in several random examples it's either not measurable, or just a tiny bit worse.

See #2613

build/three.js

@@ -15626,7 +15626,7 @@ THREE.ShaderLib = {
 			"void main() {",
 
 				"vec4 mvPosition = modelViewMatrix * vec4( position, 1.0 );",
-				"vNormal = normalMatrix * normal;",
+				"vNormal = normalize( normalMatrix * normal );",
 
 				"gl_Position = projectionMatrix * mvPosition;",
 
@@ -15900,7 +15900,7 @@ THREE.ShaderLib = {
 				THREE.ShaderChunk[ "skinnormal_vertex" ],
 				THREE.ShaderChunk[ "defaultnormal_vertex" ],
 
-				"vNormal = transformedNormal;",
+				"vNormal = normalize( transformedNormal );",
 
 				THREE.ShaderChunk[ "morphtarget_vertex" ],
 				THREE.ShaderChunk[ "skinning_vertex" ],
@@ -25754,19 +25754,19 @@ THREE.ShaderUtils = {
 
 					"#ifdef USE_SKINNING",
 
-						"vNormal = normalMatrix * skinnedNormal.xyz;",
+						"vNormal = normalize( normalMatrix * skinnedNormal.xyz );",
 
 						"vec4 skinnedTangent = skinMatrix * vec4( tangent.xyz, 0.0 );",
-						"vTangent = normalMatrix * skinnedTangent.xyz;",
+						"vTangent = normalize( normalMatrix * skinnedTangent.xyz );",
 
 					"#else",
 
-						"vNormal = normalMatrix * normal;",
-						"vTangent = normalMatrix * tangent.xyz;",
+						"vNormal = normalize( normalMatrix * normal );",
+						"vTangent = normalize( normalMatrix * tangent.xyz );",
 
 					"#endif",
 
-					"vBinormal = cross( vNormal, vTangent ) * tangent.w;",
+					"vBinormal = normalize( cross( vNormal, vTangent ) * tangent.w );",
 
 					"vUv = uv * uRepeat + uOffset;",
 

examples/js/ShaderSkin.js

@@ -323,7 +323,7 @@ THREE.ShaderSkin = {
 
 				"vViewPosition = -mvPosition.xyz;",
 
-				"vNormal = normalMatrix * normal;",
+				"vNormal = normalize( normalMatrix * normal );",
 
 				"vUv = uv * offsetRepeat.zw + offsetRepeat.xy;",
 

src/extras/ShaderUtils.js

@@ -635,19 +635,19 @@ THREE.ShaderUtils = {
 
 					"#ifdef USE_SKINNING",
 
-						"vNormal = normalMatrix * skinnedNormal.xyz;",
+						"vNormal = normalize( normalMatrix * skinnedNormal.xyz );",
 
 						"vec4 skinnedTangent = skinMatrix * vec4( tangent.xyz, 0.0 );",
-						"vTangent = normalMatrix * skinnedTangent.xyz;",
+						"vTangent = normalize( normalMatrix * skinnedTangent.xyz );",
 
 					"#else",
 
-						"vNormal = normalMatrix * normal;",
-						"vTangent = normalMatrix * tangent.xyz;",
+						"vNormal = normalize( normalMatrix * normal );",
+						"vTangent = normalize( normalMatrix * tangent.xyz );",
 
 					"#endif",
 
-					"vBinormal = cross( vNormal, vTangent ) * tangent.w;",
+					"vBinormal = normalize( cross( vNormal, vTangent ) * tangent.w );",
 
 					"vUv = uv * uRepeat + uOffset;",
 

src/renderers/WebGLShaders.js

@@ -1937,7 +1937,7 @@ THREE.ShaderLib = {
 			"void main() {",
 
 				"vec4 mvPosition = modelViewMatrix * vec4( position, 1.0 );",
-				"vNormal = normalMatrix * normal;",
+				"vNormal = normalize( normalMatrix * normal );",
 
 				"gl_Position = projectionMatrix * mvPosition;",
 
@@ -2211,7 +2211,7 @@ THREE.ShaderLib = {
 				THREE.ShaderChunk[ "skinnormal_vertex" ],
 				THREE.ShaderChunk[ "defaultnormal_vertex" ],
 
-				"vNormal = transformedNormal;",
+				"vNormal = normalize( transformedNormal );",
 
 				THREE.ShaderChunk[ "morphtarget_vertex" ],
 				THREE.ShaderChunk[ "skinning_vertex" ],