Questioin about btConvexHullShape.

[qingteng]

When I used btConvexHullShape to build a convex shape, is it a solid or just surface?
Where is the center of gravity? Is it in the shape or on the surface?

[jarno]

When I used btConvexHullShape to build a convex shape, is it a solid or just surface?

Neither. It is a pointcloud.

Where is the center of gravity?

The center of gravity (or the center of mass) is at the origin of the convex hull shape. Bullet does not calculate a center of mass. If you need the center of mass to be somewhere else, either move the points used to create the convex hull shape, or place the convex hull shape in a compound with a position transform.

As for the inertia obtained through calculateLocalInertia(), Bullet uses the bounding box and considers it solid.

---JvdL---

[qingteng]

jarno, thank you for your prompt reply. I got it.

When I used btConvexHullShape to build a convex shape, is it a solid or just surface?

Neither. It is a pointcloud.

Where is the center of gravity?

The center of gravity (or the center of mass) is at the origin of the convex hull shape. Bullet does not calculate a center of mass. If you need the center of mass to be somewhere else, either move the points used to create the convex hull shape, or place the convex hull shape in a compound with a position transform.

As for the inertia obtained through calculateLocalInertia(), Bullet uses the bounding box and considers it solid.

---JvdL---