godot rigidbody collision shape position movement break physics

epicspaces

if I animated my collision shape, or make if follow a bone, by script, the physics rigidbody breaks and became slow, and weird, what should I do ? especially if I have animated characters? as it is widely used in Unity

Megalomaniak

You should move rigidbodies by integrating forces to them. The physics system wants to control them and will fight you(to put it simply) should you try to move them by other means.

epicspaces

nah, seems you didn't understand my question at all, I don't move the rigidbody, but the collision shape itself

epicspaces

ahem ...

TwistedTwigleg

I haven't tried moving collisions shapes myself, so I cannot say for sure one way or another but I think it's not supposed to necessarily break. The performance drops are normal though, as from what I've read (documentation, QA with replies mentioning changing collision shapes) the physics engine isn't really optimized for moving CollisionShapes.

What are you trying to achieve? It may be possible to get a similar effect without moving the collision shapes, like by using multiple RigidBody nodes or by using code to simulate a 'physics-like' effect.

epicspaces

well, I have an animated character, with this script t = skel.GlobalTransform * skel.GetBoneGlobalPose(boneindex); I can attach collisionShape to my bone.

I have a project, with a giant robot, with big legs, I want my small character to pass through the legs, without colliding with the big capsule of the robot, means he must have animated collisionShapes, how can you have similar effect, it's been days trying to figure it out.

multiple RigidBody nodes and my mesh bones, it's impossible with godot? no static bodies, remember that my robot is mountable, means a rigidbody/kinematic body. the robot must collide with other robots, collision between staticbodies doesn't exist

epicspaces

animating collision shapes cause the same problem, sounds it's a dead end for my game, time to switch to another engine, so either someone solves this or I switch back to Unity, that I miss so much, because Godot can't make such kind of games

In the docs, it says : On top of that, avoid translating, rotating, or scaling CollisionShapes to benefit from the physics engine's internal optimizations. who wrote that, who ever wrote this I tell you :-1: it's all about translating, rotating, or scaling CollisionShapes that we enjoy building and benefiting for the max extra realism for our games

epicspaces

well Idon't believe its working this time : :) Skeleton skel = GetChild(0).GetNode("Armature/Skeleton") as Skeleton; Spatial spc = GetChild(1) as Spatial; Transform tsk = spc.GlobalTransform; tsk =skel.GlobalTransform * skel.GetBoneGlobalPose(8); tsk.basis.Scale =spc.GlobalTransform.basis.Scale; // I reset the scale spc.GlobalTransform = tsk;

oops, I think I was mixing physicalbones and my rigidbody, sorry I forgot to remove them one moment I was going to kill you TwistedTwigleg

epicspaces

sounds I'm going to stick to Godot for a long time :)

TwistedTwigleg

@epicspaces said: well, I have an animated character, with this script t = skel.GlobalTransform * skel.GetBoneGlobalPose(boneindex); I can attach collisionShape to my bone.

I have a project, with a giant robot, with big legs, I want my small character to pass through the legs, without colliding with the big capsule of the robot, means he must have animated collisionShapes, how can you have similar effect, it's been days trying to figure it out.

multiple RigidBody nodes and my mesh bones, it's impossible with godot? no static bodies, remember that my robot is mountable, means a rigidbody/kinematic body. the robot must collide with other robots, collision between staticbodies doesn't exist

Yeah, you can have multiple RigidBody nodes attached to mesh bones. You can set them to static and then have them follow each bone node.

If you want to use a large capsule shape to move the robot but still have the smaller entities go through, what you can do is put the large capsule and KinematicBody node on it's own collision layer. You want to make this KinematicBody on a layer that the entities cannot collide with, but the capsule can still collide with the ground. Then you can attach the RigidBody nodes to the bones, set it to a layer that the entities can see, and then it should work. The entities will still be able to collide with the smaller RigidBody limbs, while the Robot itself can use the large capsule KinematicBody for movement.

I have made a makeshift physics bone as part of Twisted IK 2, so I'm pretty confident something like the method above would work. I'm not sure how difficult it would be to fully implement into a game though.

oops, I think I was mixing physicalbones and my rigidbody, sorry I forgot to remove them one moment I was going to kill you TwistedTwigleg

Well, PhyiscalBones are different than RigidBody nodes. They have their own physics that ultimately uses a RigidBody under the hood, but how they are interacted with and used is slightly different. That might explain why the behavior wasn't working quite as expected.

Also, I am going to assume you are meaning the "one moment I was going to kill you TwistedTwigleg" in jest. However, these types of jokes are, at best, in poor taste. Joking around causing harm to another person is against forum rules (6, 15, and 18 specifically) and should be avoided. I am fairly positive you meant this as a joke, which is why I am just mentioning it here so you know moving forward to avoid this type of jesting on the forums.

sounds I'm going to stick to Godot for a long time :smile:

So it's working then? If so, great! I'm glad you were able to figure it out :smile:

Megalomaniak

It's also perhaps worth reading through the following: https://markdownpastebin.com/?id=d9d61e67f9d64db2bd215f165b931449

epicspaces

TwistedTwigleg I am sorry, about my words, I was joking, the little script above, attach my collision to the bone, the problem with static bodies is that they don't collide with each other. Have all a good day ! :)