Physical skeleton improvement and bug fix #28909

AndreaCatania · 2019-05-15T13:04:17Z

This PR is a rework of the physical bone that aim to fix all the current open issues and also improve the current Physical Bone by adding stability and control.

The current Physical Bone implementation is using the normal rigid bodies and joints, and it works good but it become unstable if the complexity of the skeleton is not trivial, for this reason the Featherstone algorithm got implemented thus allowing to have not only stable body but also full control of it.

When I talk about control I mean that with this PR is not only possible to create ragdoll of not animated body but is also possible control its movement by adding forces like the following:

This dummy is not animated using the animator, but it's animated controlling the motor of each bone, and the responsible code is simply:

func _process(delta):

	if Input.is_action_just_pressed("push"):

		left_arm.motor_set_rotation_target(Vector3(0, 0, 90))
		right_arm.motor_set_rotation_target(Vector3(0, 0, 90))
		left_forearm.motor_set_position_target(0)
		right_forearm.motor_set_position_target(0)

	elif Input.is_action_just_released("push"):

		left_arm.motor_set_rotation_target(Vector3(0, 0, 0))
		right_arm.motor_set_rotation_target(Vector3(0, 0, 0))
		left_forearm.motor_set_position_target(120)
		right_forearm.motor_set_position_target(120)

You don't have to deal with complex force system, but instead you can control it just by changing motor target and or velocity and some other parameters from the editor.

Thanks to this new PR is now possible to create, the a lot discussed, active ragdoll directly in GDscript, or is possible to create a completely physical walking robot, or simply is possible to have a stable ragdoll with dumpers and springs.

But test it yourself to see the new features, and if you want you can use this project that I've to used to develop this new feature:
Multibody.zip

This PR Fix:
Fixes #28707
Fixes #26618
Fixes #25564
Fixes #24968
Fixes #22823
Fixes #19002

thirdparty/bullet/BulletDynamics/Featherstone/btMultiBody.cpp

akien-mga · 2019-05-15T13:10:05Z

thirdparty/bullet/BulletDynamics/Featherstone/btMultiBody.cpp

@@ -343,6 +343,7 @@ void btMultiBody::finalizeMultiDof()
 	m_deltaV.resize(6 + m_dofCount);
 	m_realBuf.resize(6 + m_dofCount + m_dofCount * m_dofCount + 6 + m_dofCount);  //m_dofCount for joint-space vels + m_dofCount^2 for "D" matrices + delta-pos vector (6 base "vels" + joint "vels")
 	m_vectorBuf.resize(2 * m_dofCount);                                           //two 3-vectors (i.e. one six-vector) for each system dof	("h" matrices)
+	m_matrixBuf.resize(m_links.size() + 1);


Why is this change needed? It should also be PR'ed upstream if it's a bugfix.
Merging that also means that we're no longer compatible with Bullet 2.88 which is the current stable release, so if we can handle this on our end without modifying Bullet for now, that would be best.

Nope is not possible to manage it internally, I did a PR on the Bullet side also: bulletphysics/bullet3#2236 but in order to be able to use it ASAP I did it in this way

Zireael07 · 2019-05-15T13:41:18Z

@AndreaCatania: I saw you showcase ragdoll/skeleton with this dummy, where can we get the assets? Is it on the asset lib? Getting skeletons working with Blender -> Godot can be tricky, it would be great to have an easily available working sample...

AndreaCatania · 2019-05-15T13:48:35Z

@Zireael07 do you mean that you want to try it by yourself?
If yes, is the attached project not working?
If not, sorry but I didn't understood what you mean, can you please rephrase the question?

Zireael07 · 2019-05-15T14:11:29Z

I mean I could never get the skeleton exported from Blender to work, so if your dummy asset were generally available on the asset lib, it would be easier for people to get started with skeletons in Godot.

It is just a tangential question since I saw you demo'ing various skeleton stuff with always the same dummy, the dummy is therefore guaranteed to work.

AndreaCatania · 2019-05-15T14:15:26Z

Oh ok, To be fair this is where you can download it: https://www.mixamo.com/ and for this precise work I've used the skeleton from this guy: #28707 but yes indeed would be useful to make the skeleton import more easy.

I'll try to look on that in the next days

mysticfall · 2019-06-09T04:56:53Z

I'm trying to test this branch but getting the following error when I run my project. Could you give me some help to resolve this problem?

E 0:00:02:0315   This multi body can't be removed from non multi body world
  <C Source>     modules/bullet/space_bullet.cpp:518 @ remove_armature()

This updates our local copy to commit 5ec8339b6fc491e3f09a34a4516e82787f053fcc. We need a recent master commit for some new features that we use in Godot (see godotengine#25543 and godotengine#28909). To avoid warnings generated by Bullet headers included in our own module, we include those headers with -isystem on GCC and Clang. Fixes godotengine#29503.

akien-mga · 2019-06-11T11:58:25Z

#29418 is merged so you can rebase on master to fix CI.

AndreaCatania · 2019-06-12T20:01:41Z

Also this get merged bulletphysics/bullet3#2279

This weekend I'll be able to work on this.

@mysticfall you want to active the multi body world in the settings. Check the physics tab in the project settings to active it.

AndreaCatania · 2019-06-14T07:58:24Z

Done!

akien-mga · 2019-06-14T10:22:24Z

editor/spatial_editor_gizmos.cpp


-			const PhysicalBone::SliderJointData *sjd(static_cast<const PhysicalBone::SliderJointData *>(physical_bone->get_joint_data()));
-			JointSpatialGizmoPlugin::CreateSliderJointGizmo(
+			const PhysicalBone::SphericalJointData *sjd(static_cast<const PhysicalBone::SphericalJointData *>(physical_bone->get_joint_data()));


This one is unused.

akien-mga · 2019-06-14T10:22:41Z

editor/spatial_editor_gizmos.cpp

-					sdofjd->axis_data[2].linear_limit_enabled,
+		case PhysicalBone::JOINT_TYPE_PLANAR: {
+
+			const PhysicalBone::PlanarJointData *pjd(static_cast<const PhysicalBone::PlanarJointData *>(physical_bone->get_joint_data()));


Also unused.

akien-mga · 2019-06-14T10:25:18Z

Looks good to me overall. Couple unused variables which produce warnings, and disable_3d build is broken: https://travis-ci.org/godotengine/godot/jobs/545622746

Could you add some details on the changes in the body of the commit log? So that we have some information in git log on what changes are being done and why.

Rework of the physical bone that aim to fix currently open issues and also improve the current Physical Bone by adding stability and control. The current Physical Bone implementation was using the normal rigid bodies and joints, and it worked well but became unstable if the complexity of the skeleton is not trivial, for this reason the Featherstone algorithm was implemented to allowing to have not only a stable body but also full control of it. It is now not only possible to create ragdolls of non-animated bodies, but is also possible to control its movement by adding forces with the `motor_*` methods. You don't have to deal with complex force systems, but instead you can control it by simply changing the motor target and/or velocity and some other parameters from the editor. It is now possible to create active ragdolls directly from script, or for example to create a completely physical walking robot, or to have a stable ragdoll with dumpers and springs. Fixes godotengine#19002 Fixes godotengine#22823 Fixes godotengine#24968 Fixes godotengine#25564 Fixes godotengine#26618 Fixes godotengine#28707

akien-mga · 2019-07-04T13:09:15Z

I force pushed an update to fix compilation warnings and build failure with disable_3d=yes.

I also synced the documentation so that we can see the actual API changes, which are compatibility breaking, so this will be difficult to merge for 3.2, will likely have to wait for 4.0.

I tried it quickly on the 3D platformer demo and the TPS demo, and they both throw a lot of error simply when opening their main scene:

TPS demo:

ERROR: free: Invalid ID
   At: servers/physics/physics_server_sw.cpp:1414.
ERROR: shape_create: CylinderShape is not supported in GodotPhysics. Please switch to Bullet in the Project Settings.
   At: servers/physics/physics_server_sw.cpp:77.
ERROR: get: Condition ' !p_rid.is_valid() ' is true. returned: __null
   At: ./core/rid.h:153.
ERROR: shape_set_data: Condition ' !shape ' is true.
   At: servers/physics/physics_server_sw.cpp:107.
ERROR: free: Invalid ID
   At: servers/physics/physics_server_sw.cpp:1414.
ERROR: set_data: Condition ' !d.has("cell_size") ' is true.
   At: servers/physics/shape_sw.cpp:1650.
ERROR: free: Invalid ID
   At: servers/physics/physics_server_sw.cpp:1414.
ERROR: get: Condition ' !p_rid.is_valid() ' is true. returned: __null
   At: ./core/rid.h:153.
ERROR: body_attach_object_instance_id: Condition ' !body ' is true.
   At: servers/physics/physics_server_sw.cpp:679.
ERROR: free: Invalid ID
   At: servers/physics/physics_server_sw.cpp:1414.
ERROR: free: Invalid ID
   At: servers/physics/physics_server_sw.cpp:1414.

3D platformer:

ERROR: remove_armature: This multi body can't be removed from non multi body world
   At: modules/bullet/space_bullet.cpp:518.
ERROR: remove_armature: This multi body can't be removed from non multi body world
   At: modules/bullet/space_bullet.cpp:518.
ERROR: remove_armature: This multi body can't be removed from non multi body world
   At: modules/bullet/space_bullet.cpp:518.
ERROR: remove_armature: This multi body can't be removed from non multi body world
   At: modules/bullet/space_bullet.cpp:518.
ERROR: remove_armature: This multi body can't be removed from non multi body world
   At: modules/bullet/space_bullet.cpp:518.
WARNING: _notification: AnimationTreePlayer has been deprecated. Use AnimationTree instead.
   At: scene/animation/animation_tree_player.cpp:407.
ERROR: remove_armature: This multi body can't be removed from non multi body world
   At: modules/bullet/space_bullet.cpp:518.
ERROR: remove_armature: This multi body can't be removed from non multi body world
   At: modules/bullet/space_bullet.cpp:518.
ERROR: remove_armature: This multi body can't be removed from non multi body world
   At: modules/bullet/space_bullet.cpp:518.
ERROR: remove_armature: This multi body can't be removed from non multi body world
   At: modules/bullet/space_bullet.cpp:518.
ERROR: remove_armature: This multi body can't be removed from non multi body world
   At: modules/bullet/space_bullet.cpp:518.

AndreaCatania · 2019-07-05T05:46:50Z

The APIs doesn't changed too much but some things are not compatible since I've also improved a bit the APIs.

However the error that you got are mostly because you have to active the multibody world to use it.

This updates our local copy to commit 5ec8339b6fc491e3f09a34a4516e82787f053fcc. We need a recent master commit for some new features that we use in Godot (see godotengine#25543 and godotengine#28909). To avoid warnings generated by Bullet headers included in our own module, we include those headers with -isystem on GCC and Clang. Fixes godotengine#29503.

rodolforg · 2019-11-25T02:49:56Z

Won't this PR be able to 3.2 (or 3.1.2)? :'(

maystey · 2019-12-16T17:30:03Z

@AndreaCatania I'm having trouble with the motor velocity targets. In all of my testing nothing seems to happen when I set a velocity target (in the inspector or with scripts).

This includes the "Snake" actor in your demo project (I uncommented the line in the script that set the velocity). I increased the max impulse of the chosen physical bone, but still got nothing.

I don't see any errors for this, just no change in the simulation.

vickylance · 2020-05-12T06:37:07Z

@AndreaCatania Is this fix by any chance going to be merged for 3.2.2 release?

Calinou · 2020-05-12T07:17:33Z

@vickylance There are many merge conflicts in this pull request, and 3.2.2 is very close to being released, so I doubt it.

akien-mga · 2020-06-20T20:52:02Z

@AndreaCatania What's the status on this PR for master (and possibly a version for 3.2)?

aaronfranke · 2020-06-30T21:33:33Z

This PR has not received any new commits from the author for over a year and has many conflicts, closing.

If this is rebased and updated to work with the latest master branch, this can be re-opened or a new PR can be opened.

AndreaCatania · 2020-07-07T15:37:32Z

I'll rebase this work on master. Not sure if it's good to back port the code at this point to 3.2. I'll open another Pr.

AndreaCatania added bug enhancement topic:physics labels May 15, 2019

AndreaCatania added this to the 3.2 milestone May 15, 2019

AndreaCatania requested a review from akien-mga as a code owner May 15, 2019 13:04

This was referenced May 15, 2019

Ragdoll / Physical Bones issue #19002

Open

Nodes attached to a KinematicBody randomly get stuck in space #16994

Closed

Physical bone joint bug #26060

Closed

akien-mga reviewed May 15, 2019

View reviewed changes

thirdparty/bullet/BulletDynamics/Featherstone/btMultiBody.cpp Outdated Show resolved Hide resolved

AndreaCatania mentioned this pull request May 15, 2019

ragdoll simulation twitches in simple humanoid ragdoll #28707

Open

akien-mga reviewed May 15, 2019

View reviewed changes

AndreaCatania force-pushed the multibody branch from 30094a0 to 21c4cf1 Compare May 16, 2019 06:14

akien-mga mentioned this pull request May 16, 2019

Revert "Revert "Implemented terrain raycast acceleration"" #28928

Merged

AndreaCatania force-pushed the multibody branch 2 times, most recently from f88238c to a73ad18 Compare May 17, 2019 13:18

AndreaCatania force-pushed the multibody branch from df951aa to f32ca44 Compare June 14, 2019 07:55

akien-mga reviewed Jun 14, 2019

View reviewed changes

akien-mga requested a review from reduz June 14, 2019 10:25

mysticfall mentioned this pull request Jun 16, 2019

Erratic behaviour with physical bones (ragdoll) #29833

Closed

akien-mga force-pushed the multibody branch from f32ca44 to c6712d2 Compare July 4, 2019 13:05

AndreaCatania requested a review from a team as a code owner July 4, 2019 13:05

akien-mga added the breaks compat label Jul 4, 2019

akien-mga modified the milestones: 3.2, 4.0 Jul 4, 2019

akien-mga removed the request for review from a team July 4, 2019 13:09

owstetra mentioned this pull request Nov 22, 2019

Creating a Physical bones for Ragdoll will Crash the Engine after Changing/Reloading a Scene #33812

Closed

fire mentioned this pull request Feb 24, 2020

Add a method to get the impact force when a RigidBody hits another body godotengine/godot-proposals#487

Open

aaronfranke added the needs work label Apr 16, 2020

AndreaCatania mentioned this pull request Jun 7, 2020

Add support for Bullet's btMultiBody #16426

Closed

aaronfranke closed this Jun 30, 2020

aaronfranke added archived salvageable labels Jun 30, 2020

akien-mga mentioned this pull request Oct 1, 2020

Move joint does not work #26618

Open

AndreaCatania mentioned this pull request Dec 19, 2020

[3.2] PhysicalBone inherited from RigidBody #44150

Closed

fire mentioned this pull request Jun 14, 2021

Mesh deformed by skeleton doesn't update data properly #49575

Closed

AndreaCatania mentioned this pull request Mar 3, 2022

Make PhysicalBone3D inherit RigidDynamicBody3D #58658

Closed

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Physical skeleton improvement and bug fix #28909

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Physical skeleton improvement and bug fix #28909

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