Weird box behavior

[tzaeschke]

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Boxes sometimes fall very slow or not at all:

• DemoTrimesh: If the fourth dropped body is a Box, it will land on an edge and then fall very slowly
• DemoHeightfield: If the first item is a box, it will land on it's edge and just stay there until it is knocked over by another item.

In summary, box collision is recognized just fine, but the resulting forces on the box appear to be much too weak.

The DemoTrimesh problem is reproducible in ODE (16.3), the DemoHeightfield problem is not reproducible in ODE.

Preliminary findings

The DemoHeightfield problem goes away when using the ODE/C++ order for randomized position (x,y,z). Using the Java order in C++ does not reproduce the problem.

Even with identical starting positions, ODE and ode4j show slightly different initial contact positions. Also, ode4j reports around 803/806 collisions before the second contact appears while ODE shows only 527/529. When counting only contact, for ode4j the 22nd contact is the first double-contact, while for ODE it is the 18th.