Testing the impact of normalization of transformed normals in vertex shaders...

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" ],