Add optional collision detector: BulletCollisionDetector

[jslee02]

DART has 3 collision detector types:

• FCLMeshCollisionDetector (default)
• FCLCollisionDetector
• DARTCollisionDetector

Both of FCLMeshCollisionDetector and FCLCollisionDetector are based on fcl. The difference between them is that FCLMeshCollisionDetector convert all the primitive shapes to meshs for collision detection while fcl uses primitive shapes of 'fcl'.

Some simulation requires analytic collision information using primitive shapes for example rolling wheel for vehicle simulation. In this sense, FCLCollisionDetector or DARTCollisionDetector is good solution instead of FCLMeshCollisionDetector. However, they have issues to use as default collision detector of DART.

fcl returns only one contact point for one collision pairs. This leads to unexpected behavior. See [#59] for the detail. Whereas DARTCollisionDetector does not cover all the shapes of DART. It supports only BoxShape and Sphere.

Under current circumstance, BulletCollision may be considerable solution. It supports primitive shapes and mesh together and returns reasonable number of contact points for primitive shapes. Of course Bullet is another physics engine as it is. We uses BulletCollision component only for collision detection and separate debian package of it is delivered since Ubuntu 13.10.

This may not our long term solution but I think it is worth in case of that analytic collision solution for primitive shapes and mesh support are required at the same time. Also this pull request does not increase mandatory dependency. When BulletCollision is installed on the machine, then cmake detect it and add BulletCollsisionDetector of DART.

[ljklonepiece]

Hi there, just wondering is there any chance DARTCollisionDetector will support MeshShape objects soon?