Due to wrong first collision response when my objects fall, I replace (for a test cube shape) the convex hull child shape ,in main compound shape, with an equivalent btBoxShape, and then it works fine.
However, I've checked the points I add into the convex hull, they are correct.
Is there special task to do when initializing convex hull shapes ?
Another thing : Is there a reference document about bullet (with all objects, methods , .... description) ?