For 2D:
Raycast CCD now works the same as in 3D, it changes the body's velocity
to place it at the impact position instead of generating a contact point
that causes a wrong push back.
For both 2D and 3D:
The raycast CCD process reads and modifies body velocities, so it needs
to be moved to pre_solve() instead of setup() to be processed linearly
on the main thread, otherwise multithreading can cause some CCD results
to be randomly lost when multiple collisions occur.
Makes the API for forces and impulses more flexible, easier to
understand and harmonized between 2D and 3D.
Rigid bodies now have 3 sets of methods for forces and impulses:
-apply_impulse() for impulses (one-shot and time independent)
-apply_force() for forces (time dependent) applied for the current step
-add_constant_force() for forces that keeps being applied each step
Also updated the documentation to clarify the different methods and
parameters in rigid body nodes, body direct state and physics servers.
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.
Helps with discovery and setup of physics solver settings, in a specific
project settings section for both 2D and 3D.
Other changes for cleanup:
-Removed unused space parameters in 3D
SPACE_PARAM_BODY_ANGULAR_VELOCITY_DAMP_RATIO
SPACE_PARAM_CONSTRAINT_DEFAULT_BIAS
-Added custom solver bias for Shape3D (same as Shape2D)
-Improved documentation for solver settings
Clarified space parameters for contacts and added missing ones.
List of changes:
-Add contact bias to space parameters
-Add solver iterations to space parameters, instead of a specific
physics server function
-Renamed BODY_MAX_ALLOWED_PENETRATION to CONTACT_MAX_ALLOWED_PENETRATION
to make it consistent with other contact parameters
Changed the algorithm for solving contacts to keep previous contacts as
long as they are under the max separation threshold to keep contact
impulses more consistent and contacts more stable.
Also made 2D consistent with 3D and changed some default parameters:
-Contact bias is now 0.8 instead of 0.3 to avoid springy contacts
-Solver iterations are 16 instead of 8 by default for better stability
Performance considerations:
Tested with stress tests that include lots of contacts from overlapping
bodies.
3D: There's no measurable difference in performance.
2D: Performance is a bit lower (close to 10% slower in extreme cases)
The benefit for 2D physics to be much more stable outweighs the slight
decrease in performance, and this could be alleviated by changing the
algorithm to use jacobians for contact solving to help with cache
efficiency and memory allocations.
Bounce calculation now uses the previous frame's velocity, so it's
consistent with the actual motion of the bodies involved and not the
yet-to-be-applied forces.
When bounce is 1, using the current velocity was causing the new forces
(including gravity) to be taken into account, which lead to the bounce
velocity to be higher than the falling velocity at the moment of impact,
adding more and more energy over time.
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.
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.
Center of mass in body's local space is more useful than the transformed
one in some cases, like drawing its position for debug.
It's especially useful to get the generated local center of mass when
in auto mode (by default).
Physics Server BODY_PARAM_CENTER_OF_MASS:
Now always returns the local center of mass, instead of setting a local
center of mass and getting a transformed one.
This causes compatibility breaking, but it makes more sense for the
parameter to be consistent between getter and setter.
Direct Body State:
There are now two properties, because both of them can be useful in
different situations.
center_of_mass: relative position in global coordinates (same as before)
center_of_mass_local: position in local coordinates
Same as what is already done for shape queries, applied to point and ray
queries. Easier to document and more flexible to add more parameters.
Also expose intersect_point method to script in 3D.
Remove intersect_point_on_canvas in 2D, replaced with a parameter.
Damping values are now non-negative.
Add new properties linear_damp_mode and angular_damp_mode to set the way
RigidDynamicBody and PhysicalBone (2D & 3D) use damping values.
It can now be Combine (default) to add to the default/areas, or Replace
to override the value completely (current behavior).
Should be changing the local center of mass, which is then transformed
into `center_of_mass`.
It was causing the center of mass to be always in (0,0) by default with
multiple shapes.
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
GodotBody3D::_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).
Same logic as what was done in 3D, applied to 2D center of mass.
Also did some minor cleanup in 3D and fixed center of mass transform
during the first frame after teleporting a dynamic body.
Added a parameter in test_body_motion to exclude attached objects from
collision, used to avoid collision with all TileMap tiles with moving
platform motion instead of just the one tile the character touches.
Same changes made in 3D for consistency, and handling potential similar
cases.
-Physics servers test body motion use a class to hold parameters instead
of multiple arguments to make it more readable and flexible since there
are many options
-Improved documentation for test body motion and kinematic collision
-Removed read-only properties for body motion results (not handled in
scripts, so they should be get_ methods only instead)
Shape metadata was only used to get tile information when colliding with
tilemaps. It's not needed anymore since there's an API in tilemap using
body ids instead.
Allows 2D character controller to work without applying gravity when
touching the ground (also more safely in 3D), and collision detection
is more flexible with different safe margin values.
Character 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
Extra CharacterBody changes:
-2D: apply changes made in 3D for stop on slope and floor snap that help
fixing some jittering cases
-3D: fix minor inconsistencies in stop on slope and floor snap logic
RigidDynamicBody modes are replaced with several properties to make their
usage clearer:
-lock_rotation: disable body's rotation (instead of MODE_LOCKED)
-freeze: no gravity or forces (instead of MODE_STATIC and MODE_KINEMATIC)
-freeze_mode: Static (can be only teleported) or Kinematic (can be animated)
Also renamed MODE_DYNAMIC_LOCKED to MODE_DYNAMIC_LINEAR in the physics
servers.
