Ray.intersectWhere(…) finds the intersection between the ray and a triangle defined by three points. The code fails to detect intersections along the edge from the last point back to the first.
Here's the diff for the fix:
com.jme.math.Ray
Index: src/com/jme/math/Ray.java
===================================================================
--- src/com/jme/math/Ray.java (revision 4056)
+++ src/com/jme/math/Ray.java (working copy)
@@ -220,7 +220,7 @@
}
float dirDotDiffxEdge2 = sign * direction.dot(diff.cross(edge2, edge2));
- if (dirDotDiffxEdge2 > 0.0f) {
+ if (dirDotDiffxEdge2 >= 0.0f) {
float dirDotEdge1xDiff = sign
* direction.dot(edge1.crossLocal(diff));
if (dirDotEdge1xDiff >= 0.0f) {
And here's a unit test that exercises the method (NB - the current code fails on the third pick test):
package com.jme.math;
public class TestRay extends junit.framework.TestCase {
private Vector3f v0;
private Vector3f v1;
private Vector3f v2;
public void setUp() throws Exception {
v0 = new Vector3f(-1f,-1f,-1f);
v1 = new Vector3f(+1f,-1f,-1f);
v2 = new Vector3f(+1f,+1f,-1f);
}
public void testIntersectWhere() throws Exception {
Vector3f intersectionPoint = new Vector3f();
Ray pickRay;
// inside triangle
pickRay = new Ray(new Vector3f(0.5f,-0.5f,3f),new Vector3f(0f,0f,-1f));
assertTrue(pickRay.intersectWhere(v0, v1, v2, intersectionPoint));
// horizontal edge
pickRay = new Ray(new Vector3f(0f,-1f,3f),new Vector3f(0f,0f,-1f));
assertTrue(pickRay.intersectWhere(v0, v1, v2, intersectionPoint));
// diagonal edge
pickRay = new Ray(new Vector3f(0f,0f,3f),new Vector3f(0f,0f,-1f));
assertTrue(pickRay.intersectWhere(v0, v1, v2, intersectionPoint));
// vertical edge
pickRay = new Ray(new Vector3f(+1f,0f,3f),new Vector3f(0f,0f,-1f));
assertTrue(pickRay.intersectWhere(v0, v1, v2, intersectionPoint));
// v0
pickRay = new Ray(new Vector3f(-1f,-1f,3f),new Vector3f(0f,0f,-1f));
assertTrue(pickRay.intersectWhere(v0, v1, v2, intersectionPoint));
// v1
pickRay = new Ray(new Vector3f(+1f,-1f,3f),new Vector3f(0f,0f,-1f));
assertTrue(pickRay.intersectWhere(v0, v1, v2, intersectionPoint));
// v2
pickRay = new Ray(new Vector3f(1f,1f,3f),new Vector3f(0f,0f,-1f));
assertTrue(pickRay.intersectWhere(v0, v1, v2, intersectionPoint));
// outside horizontal edge
pickRay = new Ray(new Vector3f(0f,-1.1f,3f),new Vector3f(0f,0f,-1f));
assertFalse(pickRay.intersectWhere(v0, v1, v2, intersectionPoint));
// outside diagonal edge
pickRay = new Ray(new Vector3f(-0.1f,0.1f,3f),new Vector3f(0f,0f,-1f));
assertFalse(pickRay.intersectWhere(v0, v1, v2, intersectionPoint));
// outside vertical edge
pickRay = new Ray(new Vector3f(+1.1f,0f,3f),new Vector3f(0f,0f,-1f));
assertFalse(pickRay.intersectWhere(v0, v1, v2, intersectionPoint));
// inside triangle but ray pointing other way
pickRay = new Ray(new Vector3f(-0.5f,-0.5f,3f),new Vector3f(0f,0f,+1f));
assertFalse(pickRay.intersectWhere(v0, v1, v2, intersectionPoint));
}
}
