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.
This can be used to distinguish between integrated, dedicated, virtual
and software-emulated GPUs. This in turn can be used to automatically
adjust graphics settings, or warn users about features that may run
slowly on their hardware.
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.
This reduces visible banding in indirect lighting and reflections.
Sharp reflections now match more closely the original scene.
The downside of this change is that clipping may appear in reflections
in extremely bright scenes, but this should not be a concern in most
scenes.
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
The message about SpatialMaterial conversion was turned into a warning,
as it can potentially interfere with porting projects from Godot 3.x
(if there's a bug in the conversion code).
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.
We prefer to prevent using chained assignment (`T a = b = c = T();`) as this
can lead to confusing code and subtle bugs.
According to https://en.wikipedia.org/wiki/Assignment_operator_(C%2B%2B), C++
allows any arbitrary return type, so this is standard compliant.
This could be re-assessed if/when we have an actual need for a behavior more
akin to that of the C++ STL, for now this PR simply changes a handful of
cases which were inconsistent with the rest of the codebase (`void` return
type was already the most common case prior to this commit).
In scenes that have little to no overdraw, disabling the depth prepass
can give a small performance boost. Nonetheless, in most other scenarios,
the depth prepass should be left enabled as it improves performance
significantly.
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.
Regression fix, gravity was accumulated between frames after some
changes around area gravity calculation.
Also got rid of unused member and method in soft body class.
Replaced the previous implementation for backface collision handling (in
test_axis function from SAT algorithm) with much simpler logic in the
collision generation phase with face shapes, in order to get rid of
wrong contacts when backface collision is disabled.
Now it just ignores the generated collision if the contact normal is
against the face normal, with a threshold to keep edge contacts.
Added a special case for soft bodies to invert the collision instead of
ignoring it, because for now it's the best solution to avoid soft bodies
to go through concave shapes (they use small spheres). This might be
replaced with a better algorithm for soft bodies later.
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.
