Frustum: Support reversed depth in `setFromProjectionMatrix()` (#31464)

* Support reversed depth

* Support reversed depth

src/math/Frustum.js

@@ -89,9 +89,10 @@ class Frustum {
 	 *
 	 * @param {Matrix4} m - The projection matrix.
 	 * @param {(WebGLCoordinateSystem|WebGPUCoordinateSystem)} coordinateSystem - The coordinate system.
+	 * @param {boolean} [reversedDepth=false] - Whether to use a reversed depth.
 	 * @return {Frustum} A reference to this frustum.
 	 */
-	setFromProjectionMatrix( m, coordinateSystem = WebGLCoordinateSystem ) {
+	setFromProjectionMatrix( m, coordinateSystem = WebGLCoordinateSystem, reversedDepth = false ) {
 
 		const planes = this.planes;
 		const me = m.elements;
@@ -104,19 +105,29 @@ class Frustum {
 		planes[ 1 ].setComponents( me3 + me0, me7 + me4, me11 + me8, me15 + me12 ).normalize();
 		planes[ 2 ].setComponents( me3 + me1, me7 + me5, me11 + me9, me15 + me13 ).normalize();
 		planes[ 3 ].setComponents( me3 - me1, me7 - me5, me11 - me9, me15 - me13 ).normalize();
-		planes[ 4 ].setComponents( me3 - me2, me7 - me6, me11 - me10, me15 - me14 ).normalize();
 
-		if ( coordinateSystem === WebGLCoordinateSystem ) {
+		if ( reversedDepth ) {
 
-			planes[ 5 ].setComponents( me3 + me2, me7 + me6, me11 + me10, me15 + me14 ).normalize();
+			planes[ 4 ].setComponents( me2, me6, me10, me14 ).normalize(); // far
+			planes[ 5 ].setComponents( me3 - me2, me7 - me6, me11 - me10, me15 - me14 ).normalize(); // near
 
-		} else if ( coordinateSystem === WebGPUCoordinateSystem ) {
+		} else {
 
-			planes[ 5 ].setComponents( me2, me6, me10, me14 ).normalize();
+			planes[ 4 ].setComponents( me3 - me2, me7 - me6, me11 - me10, me15 - me14 ).normalize(); // far
 
-		} else {
+			if ( coordinateSystem === WebGLCoordinateSystem ) {
+
+				planes[ 5 ].setComponents( me3 + me2, me7 + me6, me11 + me10, me15 + me14 ).normalize(); // near
+
+			} else if ( coordinateSystem === WebGPUCoordinateSystem ) {
 
-			throw new Error( 'THREE.Frustum.setFromProjectionMatrix(): Invalid coordinate system: ' + coordinateSystem );
+				planes[ 5 ].setComponents( me2, me6, me10, me14 ).normalize(); // near
+
+			} else {
+
+				throw new Error( 'THREE.Frustum.setFromProjectionMatrix(): Invalid coordinate system: ' + coordinateSystem );
+
+			}
 
 		}