Non-world aligned bounding box

[chucksspencer]

I'd like to get a rough bounding box for any given shape in my scene. I'd like the bounding box aligned to the axes of that object's transformation rather than the world's axes. I'm trying the following:

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  btVector3 aabbMin;
  btVector3 aabbMax;
  btTransform bodyTrans = body->getWorldTransform();
  body->getCollisionShape()->getAabb(bodyTrans, aabbMin, aabbMax);

But that doesn't seem to generate any different result than

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   body->getAabb(abbMin, abbMax);

In either case the method returns bounds that seem to be in the world space rather than the object's local space.

What am I missing, here?

- Chuck

[Erwin Coumans]

Use the identity transform, to compute the local space AABB:

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btVector3 aabbMin;
btVector3 aabbMax;
body->getCollisionShape()->getAabb(btTransform::getIdentity(), aabbMin, aabbMax);

This is the local AABB, in body space.
Once you convert this AABB into world space, you will likely get the same AABB as 'body->getAabb(abbMin, abbMax);'

Hope this helps,
Erwin

[chucksspencer]

Use the identity transform, to compute the local space AABB:

Code: Select all

btVector3 aabbMin;
btVector3 aabbMax;
body->getCollisionShape()->getAabb(btTransform::getIdentity(), aabbMin, aabbMax);

This is the local AABB, in body space.
Once you convert this AABB into world space, you will likely get the same AABB as 'body->getAabb(abbMin, abbMax);'

Hope this helps,
Erwin

Ah of course. Now I see where I went wrong. Thanks again!