Support reflections in world transform

[WestLangley]

As proposed, and discussed, in #12720.

[mrdoob]

Sweet!

[mrdoob]

Thanks!

[looeee]

I've tested this with a couple of models that were showing problems and it works great! Thanks @WestLangley 😄

[vincentfretin]

This change write lots of warnings, see #13188

[yiakwy]

@mrdoob , @looeee, @WestLangley . I think at least we need to check the determinant values and matrix type before further processing

getNormalMatrix: function ( matrix4 ) {
...
...
  // verify the dimension of matrix4
  if (matrixl4.length !== 16) {
     throw Error("Wrong Dimension of Matrix!")
   }

   return this.setFromMatrix4( matrix4 ).getInverse( this ).transpose();

},

setFromMatrix4 will return a matrix of type Matrix3

	setFromMatrix4: function ( m ) {

		var me = m.elements;

		this.set(

			me[ 0 ], me[ 4 ], me[ 8 ],
			me[ 1 ], me[ 5 ], me[ 9 ],
			me[ 2 ], me[ 6 ], me[ 10 ]

		);

		return this;

	},

The line 3400 in three.module.js getInverse should be at least replaced by

Math.abs(det) < +(1+"e-" + places) // a common numeric trick in js or es6

console.warning(msg) => log.warning(msg) // when log level lower than warning, mute it.

The original code in getinverse

		if ( det === 0 ) {

			var msg = "THREE.Matrix3: .getInverse() can't invert matrix, determinant is 0";

			if ( throwOnDegenerate === true ) {

				throw new Error( msg );

			} else {
				log.warn( msg ); // when log level lower than warning, mute it.

			}

			return this.identity();

		}

is numerically wrong. The precision call also be Math.EPILON which should have been set by polyfills.js

[WestLangley]

@yiakwy If you believe there is a three.js bug, please open a new ticket and include a live example demonstrating the issue.

We do not verify or validate function args in three.js.

Also, line numbers change with each build. Avoid referencing build file line numbers in your post.

Thanks.