Scaling and Collisions

[Steve Oldmeadow]

Scaling definitely works so I assume you mean you are dynamically scaling your game object at runtime? In that case give this a try after changing the scale of your game object: Chipmunk.UpdatedTransform(gameObject);

[runonthespot]

Does this apply to any changes to transform? I noticed some weirdness when I directly manipulate transform.position for an object- it didn't always seem to actually move the object. In my head it made sense that you might need to notify the physics engine that a transform has been moved.

[Steve Oldmeadow]

@runonthespot - yes, I believe any change to the tranform requires this. Wouldn't you be better setting the position of the Chipmunk body though?

[runonthespot]

Not really sure. In my case, I'm laying out a bunch of objects in a pattern on screen, initial layout. In my physx implementation, I just set the transform position....?

[slembcke]

So the problem is that Unity doesn't provide any generic way to tell if a transform has been changed. They can do it in the engine itself, but that's not exposed for scripts to use. So when you change the transform values, Chipmunk has no way of knowing that anything has changed.

The next best idea we had was to cache the transform's position, rotation and scale values and compare them each frame. That would be mildly expensive, and changes wouldn't be picked up until the next fixed time step. Unity 4.x+ provides a boolean that you can manually set and check for changed transforms, but it's shared by all of the scripts on a game object. That's not really a generic solution either. So Chipmunk Chipmunk.UpdatedTransform() was the best we could do. :-\