Speedup Matrix inverse (#8938)

* Speedup Matrix inverse

* Matrix4 invert speedup

src/math/Matrix3.js

@@ -204,20 +204,22 @@ THREE.Matrix3.prototype = {
 
 			return this.identity();
 		}
+		
+		var detInv = 1 / det;
 
-		te[ 0 ] = t11;
-		te[ 1 ] = n31 * n23 - n33 * n21;
-		te[ 2 ] = n32 * n21 - n31 * n22;
+		te[ 0 ] = t11 * detInv;
+		te[ 1 ] = ( n31 * n23 - n33 * n21 ) * detInv;
+		te[ 2 ] = ( n32 * n21 - n31 * n22 ) * detInv;
 
-		te[ 3 ] = t12;
-		te[ 4 ] = n33 * n11 - n31 * n13;
-		te[ 5 ] = n31 * n12 - n32 * n11;
+		te[ 3 ] = t12 * detInv;
+		te[ 4 ] = ( n33 * n11 - n31 * n13 ) * detInv;
+		te[ 5 ] = ( n31 * n12 - n32 * n11 ) * detInv;
 
-		te[ 6 ] = t13;
-		te[ 7 ] = n21 * n13 - n23 * n11;
-		te[ 8 ] = n22 * n11 - n21 * n12;
+		te[ 6 ] = t13 * detInv;
+		te[ 7 ] = ( n21 * n13 - n23 * n11 ) * detInv;
+		te[ 8 ] = ( n22 * n11 - n21 * n12 ) * detInv;
 
-		return this.multiplyScalar( 1 / det );
+		return this;
 
 	},
 

src/math/Matrix4.js

@@ -633,28 +633,30 @@ THREE.Matrix4.prototype = {
 			return this.identity();
 
 		}
+		
+		var detInv = 1 / det;
 
-		te[ 0 ] = t11;
-		te[ 1 ] = n24 * n33 * n41 - n23 * n34 * n41 - n24 * n31 * n43 + n21 * n34 * n43 + n23 * n31 * n44 - n21 * n33 * n44;
-		te[ 2 ] = n22 * n34 * n41 - n24 * n32 * n41 + n24 * n31 * n42 - n21 * n34 * n42 - n22 * n31 * n44 + n21 * n32 * n44;
-		te[ 3 ] = n23 * n32 * n41 - n22 * n33 * n41 - n23 * n31 * n42 + n21 * n33 * n42 + n22 * n31 * n43 - n21 * n32 * n43;
+		te[ 0 ] = t11 * detInv;
+		te[ 1 ] = ( n24 * n33 * n41 - n23 * n34 * n41 - n24 * n31 * n43 + n21 * n34 * n43 + n23 * n31 * n44 - n21 * n33 * n44 ) * detInv;
+		te[ 2 ] = ( n22 * n34 * n41 - n24 * n32 * n41 + n24 * n31 * n42 - n21 * n34 * n42 - n22 * n31 * n44 + n21 * n32 * n44 ) * detInv;
+		te[ 3 ] = ( n23 * n32 * n41 - n22 * n33 * n41 - n23 * n31 * n42 + n21 * n33 * n42 + n22 * n31 * n43 - n21 * n32 * n43 ) * detInv;
 
-		te[ 4 ] = t12;
-		te[ 5 ] = n13 * n34 * n41 - n14 * n33 * n41 + n14 * n31 * n43 - n11 * n34 * n43 - n13 * n31 * n44 + n11 * n33 * n44;
-		te[ 6 ] = n14 * n32 * n41 - n12 * n34 * n41 - n14 * n31 * n42 + n11 * n34 * n42 + n12 * n31 * n44 - n11 * n32 * n44;
-		te[ 7 ] = n12 * n33 * n41 - n13 * n32 * n41 + n13 * n31 * n42 - n11 * n33 * n42 - n12 * n31 * n43 + n11 * n32 * n43;
+		te[ 4 ] = t12 * detInv;
+		te[ 5 ] = ( n13 * n34 * n41 - n14 * n33 * n41 + n14 * n31 * n43 - n11 * n34 * n43 - n13 * n31 * n44 + n11 * n33 * n44 ) * detInv;
+		te[ 6 ] = ( n14 * n32 * n41 - n12 * n34 * n41 - n14 * n31 * n42 + n11 * n34 * n42 + n12 * n31 * n44 - n11 * n32 * n44 ) * detInv;
+		te[ 7 ] = ( n12 * n33 * n41 - n13 * n32 * n41 + n13 * n31 * n42 - n11 * n33 * n42 - n12 * n31 * n43 + n11 * n32 * n43 ) * detInv;
 
-		te[ 8 ] = t13;
-		te[ 9 ] = n14 * n23 * n41 - n13 * n24 * n41 - n14 * n21 * n43 + n11 * n24 * n43 + n13 * n21 * n44 - n11 * n23 * n44;
-		te[ 10 ] = n12 * n24 * n41 - n14 * n22 * n41 + n14 * n21 * n42 - n11 * n24 * n42 - n12 * n21 * n44 + n11 * n22 * n44;
-		te[ 11 ] = n13 * n22 * n41 - n12 * n23 * n41 - n13 * n21 * n42 + n11 * n23 * n42 + n12 * n21 * n43 - n11 * n22 * n43;
+		te[ 8 ] = t13 * detInv;
+		te[ 9 ] = ( n14 * n23 * n41 - n13 * n24 * n41 - n14 * n21 * n43 + n11 * n24 * n43 + n13 * n21 * n44 - n11 * n23 * n44 ) * detInv;
+		te[ 10 ] = ( n12 * n24 * n41 - n14 * n22 * n41 + n14 * n21 * n42 - n11 * n24 * n42 - n12 * n21 * n44 + n11 * n22 * n44 ) * detInv;
+		te[ 11 ] = ( n13 * n22 * n41 - n12 * n23 * n41 - n13 * n21 * n42 + n11 * n23 * n42 + n12 * n21 * n43 - n11 * n22 * n43 ) * detInv;
 
-		te[ 12 ] = t14;
-		te[ 13 ] = n13 * n24 * n31 - n14 * n23 * n31 + n14 * n21 * n33 - n11 * n24 * n33 - n13 * n21 * n34 + n11 * n23 * n34;
-		te[ 14 ] = n14 * n22 * n31 - n12 * n24 * n31 - n14 * n21 * n32 + n11 * n24 * n32 + n12 * n21 * n34 - n11 * n22 * n34;
-		te[ 15 ] = n12 * n23 * n31 - n13 * n22 * n31 + n13 * n21 * n32 - n11 * n23 * n32 - n12 * n21 * n33 + n11 * n22 * n33;
+		te[ 12 ] = t14 * detInv;
+		te[ 13 ] = ( n13 * n24 * n31 - n14 * n23 * n31 + n14 * n21 * n33 - n11 * n24 * n33 - n13 * n21 * n34 + n11 * n23 * n34 ) * detInv;
+		te[ 14 ] = ( n14 * n22 * n31 - n12 * n24 * n31 - n14 * n21 * n32 + n11 * n24 * n32 + n12 * n21 * n34 - n11 * n22 * n34 ) * detInv;
+		te[ 15 ] = ( n12 * n23 * n31 - n13 * n22 * n31 + n13 * n21 * n32 - n11 * n23 * n32 - n12 * n21 * n33 + n11 * n22 * n33 ) * detInv;
 
-		return this.multiplyScalar( 1 / det );
+		return this;
 
 	},