rigidbody won't collide with each other

Archive
1
:information_source: Attention Topic was automatically imported from the old Question2Answer platform.
:bust_in_silhouette: Asked By icqqq

I have made a rigidbody and it can collide with static body.
However, I have made a several copies of the rigidbody and they don’t collide with each other. And the rigidbody can collide with other different rigidbodies.

What’s the problem?

Thanks

Did you use a CollisionShape?

DodoIta | 2018-02-19 11:12

if it’s not scaled properly it might not work as expected, but it depends if it’s 2d or 3d.
If 2d only scale the inner nodes of the collision shape( not sure about the names) In 3d make sure the collision shape is scaled properly…Or you could check the collision shape parenting if the above are correct

originaltenka | 2018-02-19 11:36

I did use CollisionShape, otherwise the rigidbody cannot collide with static body and other rigidbodies.

icqqq | 2018-02-19 12:28

I didn’t scale the collision

icqqq | 2018-02-19 12:29

Did it work?

originaltenka | 2018-02-19 12:32

does RigidBody have Concave Polygon Shape?

volzhs | 2018-02-19 12:35

Did you enable Contact Monitoring and set Contacts Reported to 1 in options of the rigid body?
Edit: You probably have done this, but you know I am just trying to help. Just in case, you missed it…

SingingApple | 2018-02-19 12:39

yes, the RigidBody has Concave Polygon Shape.
Does it matter?

icqqq | 2018-02-19 12:59

I have tried enable Contact Monitoring and set Contacts Reported to 1 but didn’t help.
Anyway, thank you.

icqqq | 2018-02-19 13:02

I am not sure it’s intended or a bug.
but, according to my test,
RigidBody with ConcaveShape does not collide to each other.

Convex vs Convex : collide
Convex vs Concave : collide
Concave vs Concave : not collide

volzhs | 2018-02-19 18:34

I asked godot dev team about this.
it’s normal(?) for now about rigidbody collision with these conditions.

Convex vs Convex : collide
Convex vs Concave : collide
Concave vs Concave : not collide

there is -convcolonly option for exporting Convex polygon shape for collision.

Importing 3D Scenes — Godot Engine (3.0) documentation in English

volzhs | 2018-02-19 18:53

Thank you so much.
How to note your comment as answer?

BTW, why it is normal? I don’t get the idea why Concave vs Concave : not collide
Is there any reason behind?

Thanks again.

icqqq | 2018-02-20 03:15

2
:bust_in_silhouette: Reply From: 2D

This sounds like it could be a collision layer/mask issue.

Check out this post for some clarification on how to set these.

no. The rigidbody is in the same mask and layer. So it should be able to collide with its copies

icqqq | 2018-02-19 13:00

Have you tried reparenting the collision shape?

originaltenka | 2018-02-19 13:32

The collision shape is direct child of the rigidbody.
Thank you

icqqq | 2018-02-19 14:02

Can you share a project with us so we can see?

2D||!2D | 2018-02-20 04:05

3
:bust_in_silhouette: Reply From: volzhs

Rigidbody collides with each other with this polygon shape.

Convex vs Convex : collide
Convex vs Concave : collide
Concave vs Concave : not collide

There is -convcolonly option for exporting Convex polygon shape for collision.

There should be something need to implement for colliding Rigidbody with Concave polygon shape with each other.

It probably will be implemented at 3.1 or later.

Thank you so much.
But may I ask why the concave do not collide with concave?
Is it harder to implement than convex collision?

Thanks

icqqq | 2018-02-20 07:25

i am not expert on physics.
but according to document,
it seems to be internal processing to make concave polygon to multiple convex polygon to detect collision.

volzhs | 2018-02-20 09:23