Refactors the BVH to make it more generic and customizable. Instead of hard coding the system of pairable_mask and pairable_type into the BVH, this information is no longer stored internally, and instead the BVH uses callbacks both for determining whether pairs of objects can pair with each other, and for filtering cull / intersection tests.
In addition, instead of hard coding the number of trees, the BVH now supports up to 32 trees, and each object can supply a tree collision mask to determine which trees it can collide against.
This enables the BVH to scale to either the two or 3 trees needed in physics, and the single tree used without pairing in Godot 4 render tree.
Margin needs to have a high enough value for test body motion to work
properly (separate using the margin, move without then gather rest info
with the margin again).
Fixes issues with test motion returning no collision in some cases with
margin equal to 0.
(cherry picked from commit 0c354047e1)
This PR adds a define BVH_EXPAND_LEAF_AABBS which is set, which stores expanded AABBs in the tree instead of exact AABBs.
This makes the logic less error prone when considering reciprocal collisions in the pairing, as all collision detect is now taking place between expanded AABB against expanded AABB, rather than expanded AABB against exact AABB.
The flip side of this is that the intersection tests will now be less exact when expanded margins are set.
All margins are now user customizable via project settings, and take account of collision pairing density to adjust the margin dynamically.
Updating the broadphase to find new collision pairs was done after
checking for collision islands, so it was working in most cases due to
the pairing margin used in the BVH, but in case of teleported objects
the narrowphase collision could be skipped.
Now it's done before checking for collision islands, so we can ensure
that broadphase pairing has been done at the same time as objects are
marked as moved so their collision can be checked properly.
This issue didn't happen in the Octree/HashGrid because they do nothing
on update and trigger pairs directly when objects move instead.
Correct transformation of normals that works with a Basis containing non-uniform scale is difficult to get correct for those not familiar with the maths, it is also rather verbose and hard to read in calling code. This PR adds helper functions which both standardize the approach and make it clearer in calling code what is being done and why.
In all physics servers, body_get_direct_state() now silently returns
nullptr when the body has been already freed or is removed from space,
so the client code can detect this state and invalidate the body rid.
In 2D, there is no change in behavior (just no more errors).
In 3D, the Bullet server returned a valid direct body state when the
body was removed from the physics space, but in this case it didn't
make sense to use the information from the body state.
Sets `AlignOperands` to `DontAlign`.
`clang-format` developers seem to mostly care about space-based indentation and
every other version of clang-format breaks the bad mismatch of tabs and spaces
that it seems to use for operand alignment. So it's better without, so that it
respects our two-tabs `ContinuationIndentWidth`.
Changing the collision layer of a sleeping body was not triggering area
updates correctly.
Bodies need to be active for collision to be checked against already
overlapping bodies and areas.
Neighbors need to be activated too in order to handle the case where a
static body is modified (it can't be activated directly but paired
bodies need to check their collision again).
In 3D, moved the call to wakeup() from the physics server to
BodySW::_shapes_changed to make it consistent with 2D and also handle
the case where shapes are modified (_shapes_changed is called in both
this case and collision layer changes).
The BVH implementation is not checking collision layers on existing
pairs on move like other physics broadphases do.
This is solved by adding a new call to trigger pair callbacks again so
the physics engine can check layers again (specific to the BVH version,
other broadphase implementations just trigger a move like before).
These changes improve Rayshape behavior for Godot Physics 2D and 3D
when using move_and_slide with and without snapping.
Kinematic margin is now applied to ray shapes when handling snapping
collision tests and separation raycasts to help getting consistent
results in slopes and flat surfaces.
Recovery is calculated without the margin and a depth of 0 is still
considered a collision to stabilize results when on flat surface.
Recovery depth takes into account the current recovery vector (just like
test_body_motion) to fix jittering issues with multiple ray shapes due
to applying too much recovery.
Allows more flexible collision detection with different safe margin values.
Kinematic body motion changes in 2D and 3D:
-Recovery only for depth > min contact depth to help with collision
detection consistency (rest info could be lost if recovery was too much)
-Adaptive min contact depth (based on margin) instead of space parameter
Same thing that was already done in 2D, applies moving platform motion
by using a call to move_and_collide that excludes the platform itself,
instead of making it part of the body motion.
Helps with handling walls and slopes correctly when the character walks
on the moving platform.
Also made some minor adjustments to the 2D version and documentation.
Co-authored-by: fabriceci <fabricecipolla@gmail.com>
When synchronizing KinematicBody motion with moving the platform using
direct body state, only the linear velocity was taken into account.
This change exposes velocity at local point in direct body state and
uses it in move_and_slide to get the proper velocity that includes
rotations.
The Transform::xform and xform_inv are made safe for Planes when using non-uniform scaling.
Basic unit tests for Transform.
Optimization of calling sites to prevent loss of performance from the changes to xform(Plane).
In 3D, collision is disabled between kinematic/static bodies when
contacts are generated only to report them.
In 2D, this case was already fixed but the code is cleaned to make
it easier to follow.
* Safe and unsafe motion are calculated by dichotomy with a limited
number of steps. It's good for performance, but on long motions that
either collide near the beginning or near the end, the result can be
very imprecise.
* Now a factor 0.25 or 0.75 is used to converge faster when this case
happens, which allows longer motions to get more accurate collision
detection.
* Makes snap collision more precise, and helps with cases where diagonal collision on the border of a platform can lead to the character being stuck.
Additional improvements to move_and_slide:
* Handle slide canceling in move_and_collide with 0 velocity instead of
not applying it.
* Better handling of snap with custom logic to cancel sliding.
* Remove small jittering when using stop on slope, by canceling the
motion completely when the resulting motion is less than margin instead
of always projecting to the up direction (in both body motion and snap).
Co-authored-by: fabriceci <fabricecipolla@gmail.com>
Make sure the direction of the motion is preserved, unless the depth is
higher than the margin, which means the body needs depenetration in any
direction.
Also changed move_and_slide to avoid sliding on the first motion, in
order to avoid issues with unstable position on ground when jumping.
Co-authored-by: fabriceci <fabricecipolla@gmail.com>
In 3D, disabled shapes are now not added to the broadphase anymore.
Since they are removed right away when disabled, no need to check for
disabled shapes for any query that comes from the broadphase.
Also Fixes raycast queries returning disabled shapes.
In 2D, disabled shapes where already not added to the broadphase.
Remove the same unnecessary checks as in 3D.
Overall harmonized API for disabled shapes in the physics servers and
removed duplicate method.
The code is based on the current version of thirdparty/vhacd and modified to use Godot's types and code style.
Additional changes:
- backported and extended PagedAllocator to allow leaked objects
- applied patch from https://github.com/bulletphysics/bullet3/pull/3037
Dynamic BVH doesn't update the tree anymore when calling set_pairable
with no parameter change.
Also modified Godot Physics broadphase to create objects directly with
pairable (static) set correctly to make use of this optimization for the
BVH broadphase.
Note: Octree broadphase doesn't use this optimization because it forces
an update on move, so passing the proper AABB and static parameters on
creation would cause the tree to update twice.
