[Bf-codereview] Bullet Integration (issue 7092051)

[sergej.reich at googlemail.com]

Thanks for the review, a few quick comments:

> - Mesh conversion could be sped up by not adding triangles one at a
time with
> double-vertex checks, but this can be done after merge.

Right, I haven't touched that actually. Ideally we could avoid
allocating the extra mesh by using blender's mesh data directly in
bullet, would need to test if that could cause problems in cases where
the mesh changes while the simulation is running.

> - I noticed scale is always removed from objects involved with
physics, IIRC the
> game engine manages to have scaled meshes with physics so it could be
supported.

Scaling is supported, we create unscaled collision shapes because we
scale them afterwards. This also allows for dynamic scaling while the
simulation is running.

> - Id like to allow building with WITH_BULLET disabled, any hints as to
which
> branch I should look to getting the this change?

Sure, I'd do it myself but if you want, you can look here:
https://gitorious.org/~sergof/blenderprojects/sergofs-blender

> - The way groups is used I find a bit strange, instead it could flag
objects and
> store in an array? - it works as is and may be annoying to change
right now but
> noting here.
> Maybe other devs can explain why doing it this way is good.

Personally I'd prefer to get rid of the groups and just use arrays
instead, since we need them for the cache anyway. It would also make the
code much more clear.
However, Ton insists on using groups. I guess if we'd add multiple rigid
body worlds someday it would be easier to keep track of objects.

Will fix the other issues.

https://codereview.appspot.com/7092051/