Patch for btQuantizedBvh when compiling with gcc

zkunda · **Joined:** Mon Apr 19, 2010 12:59 pm **Posts:** 6

Our project is using "bullet" in linux server for collision detection.
bug:
Create btBvhTriangleMeshShape with useQuantizedAabbCompression = true, we found incrrect collision detection result frequently. If useQuantizedAabbCompression = false, everything is just perfect. But it costs much more memory!
fix:
btQuantizedBvh.h

Code:

int getTriangleIndex() const
{
       btAssert(isLeafNode());  // Get only the lower bits where the triangle index is stored
       return (m_escapeIndexOrTriangleIndex&~((~0)<<(31-MAX_NUM_PARTS_IN_BITS)));
} 

(~0)<<(31-MAX_NUM_PARTS_IN_BITS) should change to 0xffffffff<<(31-MAX_NUM_PARTS_IN_BITS)

(~0) is recognized as negative value in gcc probaly.
Shift operators for negative value is implementation-defined and gcc compiler implements defferent shift operation against visual studio c++(vs9) compiler

mi076 · **Posted:** Fri May 25, 2012 10:57 am

Have you opened an issue? I looked at C++ standard (open-std.org) and so far "<<" is undefined if on left side is negative value.
There is also one in btSoftBodyConcaveCollisionAlgorithm.h (line 48).
Thank you.

Physics Simulation Forum

Patch for btQuantizedBvh when compiling with gcc

Who is online