Merging with @NINE78 branch.

src/extras/physics/Collisions.js

@@ -152,7 +152,7 @@ THREE.CollisionSystem.prototype.rayMesh = function( r, me ) {
         var p3 = face instanceof THREE.Face4 ? me.mesh.geometry.vertices[ face.d ].position : null;
 
         if (face instanceof THREE.Face3) {
-            var nd = this.rayTriangle( rt, p0, p1, p2, d, this.collisionNormal, me.mesh.doubleSided );
+            var nd = this.rayTriangle( rt, p0, p1, p2, d, this.collisionNormal, me.mesh );
 
             if( nd < d ) {
 
@@ -167,7 +167,7 @@ THREE.CollisionSystem.prototype.rayMesh = function( r, me ) {
         
         else if (face instanceof THREE.Face4) {
             
-            var nd = this.rayTriangle( rt, p0, p1, p3, d, this.collisionNormal, me.mesh.doubleSided );
+            var nd = this.rayTriangle( rt, p0, p1, p3, d, this.collisionNormal, me.mesh );
             
             if( nd < d ) {
 
@@ -178,7 +178,7 @@ THREE.CollisionSystem.prototype.rayMesh = function( r, me ) {
 
             }
             
-            nd = this.rayTriangle( rt, p1, p2, p3, d, this.collisionNormal, me.mesh.doubleSided );
+            nd = this.rayTriangle( rt, p1, p2, p3, d, this.collisionNormal, me.mesh );
             
             if( nd < d ) {
 
@@ -197,7 +197,7 @@ THREE.CollisionSystem.prototype.rayMesh = function( r, me ) {
 
 };
 
-THREE.CollisionSystem.prototype.rayTriangle = function( ray, p0, p1, p2, mind, n, doubleSided ) {
+THREE.CollisionSystem.prototype.rayTriangle = function( ray, p0, p1, p2, mind, n, mesh ) {
 
 	var e1 = THREE.CollisionSystem.__v1,
 		e2 = THREE.CollisionSystem.__v2;
@@ -213,7 +213,7 @@ THREE.CollisionSystem.prototype.rayTriangle = function( ray, p0, p1, p2, mind, n
 	var dot = n.dot( ray.direction );
 	if ( !( dot < 0 ) ) {
 		
-		if ( doubleSided ) {
+		if ( mesh.doubleSided || mesh.flipSided ) {
 		
 			n.multiplyScalar (-1.0);
 			dot *= -1.0;