[TRACKER] Bullet Physics issues

[pouleyKetchoupp]

This tracker is for physics issues that are specific to Bullet Physics and not present in Godot Physics.

Note: Issues that can be reproduced on both Bullet and Godot Physics are listed in #45333.

RigidBody

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1. [Bullet] 3D StaticBody constant linear/angular velocity doesn't work when using Bullet #17531
   bug confirmed topic:physics +3
2. [Bullet] Rigidbody doesn't appear to apply rotation #24380
   bug confirmed topic:physics +3
3. [Bullet] 3D: long (+300 m) collision shapes for static bodies resulting in strange behaviour #36729
   bug confirmed topic:3d topic:physics +4
4. [Bullet] 3d physics stepping is two frames late for bullet physics #37702
   bug confirmed topic:3d topic:physics +4
   
5. [Bullet] Gravity is applied to RigidBody even with custom_integrator turned on #40508
   bug regression topic:physics +3
   
6. [Bullet] The Rigidbody cannot rotate after set the CollisionShape disabled first and enabled later #41617
   bug topic:physics +2
7. [Bullet] Bullet Ignores RigidBody Damping Settings When They Are Zero #42842
   bug topic:physics +2
8. [Bullet] 3D RigidBody collisions with static collision shapes still bumpy #46596
   bug confirmed topic:3d topic:physics +4
9. [Bullet] Bouncing vehicle loses velocity #47273
   bug confirmed topic:3d topic:physics +4
10. [Bullet] Gravity is not applied on RigidBody when rotated through transform change #51871
    bug topic:physics +2
11. [Bullet] Rigid Bodies "floating" if CollisionShape is a Created Convex Collision Sibling #55503
    bug confirmed topic:3d topic:physics +4
12. [Bullet] _integrate_forces(state) not reporting contacts, normals #58409
    bug topic:physics +2

KinematicBody/CharacterBody

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1. [Bullet] Kinematicbody snap drags objects down even without any velocity #22313
   bug topic:physics +2
   
2. [Bullet] move_and_slide_with_snap causes erroneous movement near edges #29392
   bug confirmed topic:physics +3
3. [Bullet] Problems with physics in 3D when using the units as intended #30742
   archived bug confirmed discussion topic:physics +5
4. [Bullet] KinematicBody slides on collision box, but doesn't on a plane #26550
   bug confirmed topic:physics +3
5. [Bullet] Seemingly inaccurate kinematic collision remainders in Bullet physics but not GodotPhysics #28717
   bug confirmed topic:physics +3
6. [Bullet] move_and_slide() causes jitter when colliding with corners between walls #32182
   bug confirmed topic:3d topic:physics +4
7. [Bullet] KinematicBody3D: is_on_floor() can become false when moving against a wall #33833
   bug confirmed topic:physics +3
8. [Bullet] move_and_slide_with_snap inconsistent is_on_floor #34081
   archived bug topic:physics +3
9. [Bullet] KinematicBody: move_and_slide_with_snap intersection edges problem #34436
   bug topic:physics +2
10. [Bullet] Jittering against two discrete, connected walls #34596
    bug topic:physics +2
11. [Bullet] GridMap collisions broke from 3.1.2 to 3.2 #35713
    archived bug topic:physics +3
12. [Bullet] KinematicBody jitters up and down when walking along a flat gridmap. #35780
    bug confirmed topic:physics +3
13. [Bullet] Inaccurate behaviour of 3D KinematicBody move_and_slide_with_snap on vertical moving platform. #36334
    bug confirmed topic:3d topic:physics +4
14. [Bullet] KinematicBody3D with move_and_slide() can stop moving completely even when the given velocity is not equal to zero #45058
    bug topic:physics +2
15. [Bullet] move_and_slide is unstable with bullet physics. #50877
    bug topic:physics +2
16. [Bullet] KinematicBody3D Stair-step method works flawlessly in Godot Physics, doesn't work with Bullet #58260
    bug confirmed topic:3d topic:physics +4
17. [Bullet] KinemeticBody still jitters against gridmap seams with 3.5 RC2 using Bullet #61616
    bug confirmed topic:physics +3

Collision detection

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1. [Bullet] Fast RigidBody always go through walls and Godot Crash because of Collision #16113
   bug confirmed topic:3d topic:physics +4
   
2. [Bullet] Box collision with Sphere not reported if sphere bounce is >0 #43224
   bug confirmed topic:3d topic:physics +4
3. [Bullet] InputEvent in StaticBody always return index 0 #43587
   bug confirmed topic:physics +3
4. [Bullet] [Needs Bullet Update] Crashing asserts in debug when using Bullet Physics with CCD enabled #43868
   bug crash topic:physics +3
5. [Bullet] Duplicate body_shape_entered reported on CollisionShapes not close to the collision (even when disabled) #44644
   bug regression topic:physics +3
   

   
6. [Bullet] Concave polygon collision shapes are completely broken in Bullet on master when built with LLVM #45264
   archived bug topic:physics +3
7. [Bullet] Rigid and Kinematic bodies use different collision detection algorithms. #47496
   bug topic:physics +2
8. [Bullet] Unable to use imported collision data in other nodes #49856
   bug confirmed topic:3d topic:import topic:physics +5
9. [Bullet] Running project gives recover from penetration error. #50628
   bug topic:3d topic:physics +3
10. [Bullet] Godot 3.x with Bullet, collision layer & mask choice affects collision accuracy #53219
    bug confirmed topic:3d topic:physics +4

Area

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1. [Bullet] area_shape is 0 in body_shape_entered and body_shape_exited #19290
   bug confirmed topic:physics +3
   
2. [Bullet] Inconsistent generation of Area body_entered/body_exited signals #22889
   bug topic:physics +2
3. [Bullet] Setting 3D gravity vector during runtime disables it instead #32196
   bug topic:3d topic:physics +3
4. [Bullet] Changing 3D gravity in BulletPhysics does not work as expected #35378
   bug topic:dotnet topic:physics +3
5. [Bullet] Area Gravity issue #32776
   bug topic:physics +2
6. [Bullet] Changing collision shape radius/extents doesn't update stationary area + area collisions #39947
   bug topic:physics +2
7. [Bullet] Area zero gravity with Bullet #40127
   bug confirmed topic:physics +3
   
8. [Bullet] Bullet physics PhysicsDirectBodyState.get_total_gravity() returns Vector3(0, 0, 0) in the first physics frame. #40314
   bug topic:physics +2
9. [Bullet] Bullet physics adds the default damping values instead of setting them #46650
   bug topic:3d topic:physics +3
10. [Bullet] Concave collision shapes not working with areas #48023
    bug topic:3d topic:physics +3

Collision queries

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1. [Bullet] Raycasting a BoxShape hints round edges/artifacts #28032
   bug confirmed topic:3d topic:physics +4
2. [Bullet] Bullet physics: scaled collision shapes return incorrect normals #30214
   topic:physics +1
3. [Bullet] PhysicsServer.intersect_shape doesn't work with shapes that aren't centered #38908
   bug confirmed topic:physics +3
4. [Bullet] Raycasts sometimes go through convex shapes and hit the far side when BT_USE_DOUBLE_PRECISION is enabled. #40586
   bug topic:physics topic:thirdparty +3
   
5. [Bullet] 3D - Raycasting onto a capsule collision, is very inacurrate, compared to a box collision #45451
   bug needs testing topic:3d topic:physics +4
6. [Bullet] collide_shape returns unintuitive/wrong values #45680
   bug confirmed documentation good first issue topic:physics +5
7. [Bullet] RayCasts get_collider_shape erroneously returns triangle index when colliding with ConcaveCollisionShape(s) #47989
   bug confirmed topic:physics +3
8. [Bullet] Collision queries with a mesh collider detect things they don't touch even when changing margin #48905
   documentation topic:physics +2
9. [Bullet] Raycast results return wrong positions #49814
   bug confirmed topic:3d topic:physics +4

Joints

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1. [Bullet] Bullet Physics HingeJoint motor stops and restarts spinning every 360° #18351
   bug confirmed topic:3d topic:physics +4
   
2. [Bullet] Rigidbodies have crazy movement when used with joints #18632
   bug confirmed topic:physics +3
   
3. [Bullet] Generic6DOFJoint node error #42286
   bug confirmed topic:physics +3
4. [Bullet] HingeJoint deprecation message prints even for default property setup #42678
   bug confirmed topic:editor topic:physics +4
5. [Bullet] Most properties in 6DOFJoint do nothing. Also if two 6DOF joints are fixed to one rigid body, only one affects it. #50210
   bug topic:3d topic:physics +3

Performance

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1. [Bullet] Performance monitor for 3D physics not working for Bullet #16540
   bug confirmed topic:3d topic:editor topic:physics +5
   
2. [Bullet] Severe lag when adding a collider to a physics object with many colliders #22064
   archived performance topic:3d topic:physics +4
   
3. [Bullet] Adding a high amount of physics bodies is significantly slower with Bullet compared to GodotPhysics #30027
   bug performance topic:3d topic:physics +4
   
4. [Bullet] Bullet Physics bad performance in GridMap #34963
   archived bug topic:3d topic:physics +4
5. [Bullet] Setting 3D body transform after add_child makes it very slow in procedural generation use cases #45598
   bug discussion topic:physics +3

Other

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1. [Bullet] None of the shapes in PhysicsServer (Bullet) are initializing their members #25304
   enhancement topic:physics +2
   
2. [Bullet] Convex Collision Sibling wrong margin with Bullet #27427
   bug confirmed discussion documentation topic:physics +5
3. [Bullet] Bullet physics breaks determinism when iterations_per_second is changed #38910
   bug topic:physics +2
   
4. [Bullet] Usage of freed memory in BulletPhysicsDirectBodyState::get_contact_collider_id when running project #44088
   bug crash topic:physics +3
5. [Bullet] Assertion `localAabbMin.getX() <= localAabbMax.getX()' failed #44663
   bug regression topic:physics +3
6. [Bullet] Crash when adding, moving and removing 3D physics nodes with collision shapes in Bullet physics #47437
   bug crash topic:physics +3

Changes in Bullet needed for 4.0 compatibility

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1. Server API changes (shapes and joint creation, thread safety, etc.) (see Make Servers truly Thread Safe #45852)
2. One-directional collision layer check for rigid bodies, soft bodies, areas (see Make physics layers and masks logic simple and consistent godot-proposals#2775)
3. Backface collision on/off for concave shapes (check if supported) (see Disable backface collision with ConcavePolygonShape by default #47139)
4. Custom center of mass and inertia (see Proper support for custom mass properties in 2D/3D physics bodies #49610) (see Expose local center of mass in physics servers #54134)
5. Removed infinite inertia and changed ray shape in character motion (see Remove infinite inertia and ray shapes from CharacterBody #51490) (see Refactor RayShape and rename to SeparationRayShape #51896)
6. Capsule height independent from radius (see Make radius & height in CapsuleShape3D independent #51522)
7. Soft Body area detection, gravity, wind (see Updated softbody handling to allow for area/softbody collision detection and application of area gravity #50785) (see Created an area-specific wind force that interacts with soft bodies #51751)
8. All physics queries use a class to hold parameters and new parameters (see Use parameter classes instead of arguments for all physics queries #54573) (see Add raycast options to hit when starting inside / hit back faces #54857)
9. Separate area space override modes (see Separate space override modes for gravity/damping in Area #54810)

[smix8]

#43243
Softbody is Bullet only so I guess this is also a Bullet Physics issue to track?

[pouleyKetchoupp]

@smix8 I'll probably make a specific tracker for soft bodies. For info, the plan for 4.0 is to implement them in Godot Physics as well.

[pouleyKetchoupp]

For info, I've just added an extra section at the end of the tracker for changes that will be needed in the Bullet server for 4.0 compatibility, since Bullet is disabled on master at the moment.

These changes will be needed either for the a Bullet plugin or for re-enabling it as a module before 4.0 release.