OgreBullet needs some love

[slapin]

• ~~OgreBullet does not support btCompoundShape which is the only way to offset collision shapes and have multiple of them per RigidBody.~~

• ~~Additionally all the CollisionShape utility functions are hidden which makes it hard to create shapes as needed from shapes and entities.~~

• Also the full two-side kinematic body is not implemented because Bullet's kinematic btRigidBody is one side and does not handle collisions. I tried to use btKinematicCharacterController but was unable to make it run properly at all, so I consider the solution in Godot which is implemented roughly of useful parts from btKinematicCharacterController (de-penetration and sweep tests) w/o strange magic mumbo-jumbo. I think the following should be done:

• [x] Add btCompoundShape support to OgreBullet.cpp https://github.com/OGRECave/ogre/pull/3363

• [x] make shape creation functions available as API. https://github.com/OGRECave/ogre/pull/3363

• [x] a API function is needed which would allow btRigidBody/btCollisionObject created outside to have Ogre listener attached for Ogre to handle the motion. https://github.com/OGRECave/ogre/pull/3364

• [ ] implement ~~Godot's move_and_slide()~~ (changed direction and implemented as btActionInterface to run by physics directly ~~(approx. till June, 9)~~ done via btPairCachingGhostObject

  • [x] Build convex shape list from btCompoundShape hierarchy
  • [x] implement de-penetration part
  • July plan:
    • Kinematic motion:
      • [ ] Implement sweep motion tests to avoid too much de-penetration (even though performance is good but a bit more robustness and stability are welcome)
      • [ ] Add floor and wall tests (most important for feature completeness and ease of use)
    • Other physics:
      • [ ] Implement simple triggers. The setup of btGhostObjects is quite hard for many people so having more simple template setup for most usecases would be useful.

[paroj]

as I did not need that functionality myself yet, I have no idea how a good API for this would look like. PRs with proposals are welcome.

[slapin]

I have that planned over weekend, so there will be PR.

[slapin]

Created one of 2 PRs.

[slapin]

All PRs created. Then I go back to implementing move_and_slide...

[slapin]

added "implement Godot's move_and_slide()" it would be easier for me to track.

[slapin]

achievement made btPairCachingGhostShape work and still sane. Muhahahahagh!!!111