   Mesh - Other objects collision
  Hi,   This is more of generic question.I have used ODE and physx physics libraries. What I wanted to ask is how come the collisions between mesh and other objects collision is never perfect. There are always some parts where the objects are able to fall through the mesh. I have seen this in ODE trimeshes and in Physx triangle meshes. This particularly happens on a bit slanted type surfaces(I maybe wrong). I understand that in discrete time steps it may fall through at high speeds or at bigger timesteps but sometimes even if the objects are traversing very slowly they easily fall through. I have also checked the normals and they are correctly oriented(I export models from blender).    Currently I am working on Physx and Directx but have no idea why this happens. Am I missing something here. Any solutions for this??Thanks   