This commit only adds callbacks which then later be used with major dependency
graph commit, keeping the upcoming commit more clean to follow.
Should be no functional changes so far still.
The issue was caused by the fix for T34108, which modified DNA in order to
get a fallback box collision shape. Not sue why it's needed, we can just get
box shape directly, without modifying user's settings.
This was a ToDo item, for mesh-based rigid body shapes (trimesh, convex)
the operator was simply using the bounding box volume, which can grossly
overestimate the volume and mass.
Calculating the actual volume of a mesh is not so difficult after all,
see e.g.
http://research.microsoft.com/en-us/um/people/chazhang/publications/icip01_ChaZhang.pdf
This patch also allows calculating the center-of-mass in the same way.
This is currently unused, because the rigid body system assumes the CoM
to be the same as the geometric object center. This is fine most of the
time, adding such user settings for "center-of-mass offset" would also
add quite a bit of complexity in user space, but it could be necessary
at some point. A number of other physical properties could be calculated
using the same principle, e.g. the moment of inertia.
Problem happens when removing a rigid body reference in a constraint,
and then jumping to the start frame right away. This will cause a full
rebuild of the rigid body world. However, the btRigidBodys are removed
before the constraints, and this leaves dangling pointers in the
btTypedConstraints, which causes corruption when deleting those
constraints later.
Fix for now is to explicitly delete constraints in advance when
rebuilding, while they still have valid btRigidBody pointers.
Ultimately the whole memory management and ownership of Bullet data
needs redesign. This is already happening in the particles_refactor
branch and could be ported to master separately:
https://developer.blender.org/diffusion/B/browse/particles_refactor/source/blender/blenkernel/intern/rigidbody.c
updates.
This file crashes on loading with NULL pointer access to curve_cache:
{F77132}
The pdInitEffectors function was amalgamating the simple
collection of effector objects with an automatic precalculation for
curve guides and the like. This precalculation requires object data
that may not be available until the DAG has finished.
Since for DAG dependencies only the list of effectors is required,
added an argument to disable precalculation when collecting effectors.
The options are:
Base: Base mesh
Deform: shape keys and deform modifiers
Final: All deformations and modifiers
It would be nice to have a way of specifying where exactly in the
modifier stack the collision shape is generated. However this is not
staight forward since the rigid body simulation is not part of the
modifier system and would require hacks to make it work.
This is not the nicest behaviour but trying to keep both bullet and
blender side objects in sync breaks in this case.
There might be a better soluion but this avoids crashes for now.
Fixes: [#35995] Delete crash on specific scene (Physics)
Now copying a scene will also duplicate groups that consist entirely of objects
that are duplicated with the scene. The rigid body world will then also pointers
to these new groups.
Since we use the rigid body transform when transforming rigid bodies
things like parents and constraints add an offset because rigid body
transforms are in global space.
Now we just don't take rigid body transform into account on simulation
start frame so there are no problems when doing the initial setup.
The problem still exists when simulation is running of course.
To properly fix this we'd have to solve parenting and constratins while
taking rigid bodies into account before and after transform.
We'll have to see if it's really needed, would like to avoid it though.
Instead of flagging the rigid body world for frame update just call
BKE_rigidbody_do_simulation() recursively for all scenes.
This avoids having to constantly check if the simulation needs to be
updated.
The rigid body world could be rebuilt on start frame and one frame after
start frame. The latter was necessary sice animation playback usually
doesn't start at start frame.
This lead to different simulations depending on which frame the
simulaton was rebuilt when animation was involved.
Now we only rebuild the world on start frame.
This is actually tricky to do since, as mentioned above, animation
playback starts on second frame. To work around this we rebuild the
world before the actual update.
The alternative would be to rebuld the world on every simulation change
(like the other simulations do it) but this is an expensive operation
and would be too slow.
While it's not a good idea to create convex hull shapes from objects
with no volume, this makes them behave a little nicer.
Fixes [#34410] Planes with Rigid Body always keep distance to colliding objects
It's implemented as a separate constraint instead of adding properties
to the existing constraints.
Motors only apply linear and angular impulses and don't limit the
movement of rigid bodies, so it's best to use them in conjunction with
other constraints to limit the degrees of freedom.
Thanks to Markus Kasten (markus111) for the initial patch.
This is a pretty rare case that can be triggered by switching rigid body
and constraint groups before simulation was validated.
Code checked for existing physics objects but was missing else block.
In rare cases this would allow the simulation to run before being
initialized (if cache is baked and reading cache fails after undo or
loading a file).
