Fixed matrix decomposition with negative scaling

src/Math/babylon.math.ts

@@ -3283,13 +3283,13 @@
             translation.y = this.m[13];
             translation.z = this.m[14];
 
-            var xs = MathTools.Sign(this.m[0] * this.m[1] * this.m[2] * this.m[3]) < 0 ? -1 : 1;
-            var ys = MathTools.Sign(this.m[4] * this.m[5] * this.m[6] * this.m[7]) < 0 ? -1 : 1;
-            var zs = MathTools.Sign(this.m[8] * this.m[9] * this.m[10] * this.m[11]) < 0 ? -1 : 1;
+            scale.x = Math.sqrt(this.m[0] * this.m[0] + this.m[1] * this.m[1] + this.m[2] * this.m[2]);
+            scale.y = Math.sqrt(this.m[4] * this.m[4] + this.m[5] * this.m[5] + this.m[6] * this.m[6]);
+            scale.z = Math.sqrt(this.m[8] * this.m[8] + this.m[9] * this.m[9] + this.m[10] * this.m[10]);
 
-            scale.x = xs * Math.sqrt(this.m[0] * this.m[0] + this.m[1] * this.m[1] + this.m[2] * this.m[2]);
-            scale.y = ys * Math.sqrt(this.m[4] * this.m[4] + this.m[5] * this.m[5] + this.m[6] * this.m[6]);
-            scale.z = zs * Math.sqrt(this.m[8] * this.m[8] + this.m[9] * this.m[9] + this.m[10] * this.m[10]);
+            if (this.determinant() <= 0) {
+                scale.y *= -1;
+            }
 
             if (scale.x === 0 || scale.y === 0 || scale.z === 0) {
                 rotation.x = 0;