PlaneMesh Collisions

[eee-c]

This may be expected behavior, but seemed worth a mention. If a BoxMesh face shares a plane with a PlaneMesh, then collisions are registered — even if the two object do not overlap.

An example is available at http://eee-c.github.com/threejs-my/collision_test.html. In the JavaScript console, You can see that, even though no cube is touching the green plane at the start of the animation, a collision event with the plane is registered.

More details (way too many really) are available at: http://japhr.blogspot.com/2012/08/collision-events-in-physijs.html

[chandlerprall]

If you have any suggestions on how to document this behavior I would love to hear it :)

In Three.js a plane has edges, mathematical planes (which are used in physics engines) do not have these boundaries but instead expand infinitely in both directions. If I understand your examples correctly, this is what you are observing. Try implementing Rob Dodson's suggestion and see if that behaves as you expect.

I'm enjoying looking at your blog posts and seeing what you're working on. Feel free to ask if you get stuck on something else like the object grouping. The #three.js IRC room is a great place for the 3D-related questions and I'm usually in that channel during the week.