Add line separation algorithm

index.js

@@ -812,6 +812,10 @@ define(function(require, exports, module){
             return BSPTree.sign(normal.dot(point.clone().sub(pointOnPlane)));
         }
         
+        BSPTree.isZero = function(x){
+            return Math.abs(x) < BSPTree.SIGN_EPSILON;
+        }
+        
         BSPTree.sign = function(x){
             if(Math.abs(x) < BSPTree.SIGN_EPSILON){
                 return 0;
@@ -884,7 +888,21 @@ define(function(require, exports, module){
         }
         
         BSPTree.LineNode.prototype.separate = function(normal, point){
+            var upper = point.clone().sub(this.element.v1.positionWorld);
+            upper = upper.dot(normal);
+            
+            var l0 = this.element.v2.positionWorld;
+            
+            var l = l0.clone().sub(this.element.v1.positionWorld);
+            var lower = l.dot(normal);
+            
+            if(lower === 0) return this;
+            
+            var d = upper / lower;
+            
+            var intersectionPoint = l.multiplyScalar(d).add(l0);
             
+            return intersectionPoint;
         }
         
         BSPTree.TriangleNode = function(element){