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.
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.
