Crash in 3d when the collision shape has no depth

[fgadaleta]

Running this demo (no changes made) https://github.com/jcornaz/heron/blob/main/examples/demo.rs

I get this

thread 'Compute Task Pool (0)' panicked at 'assertion failed: proxy.aabb.maxs[dim] >= self.min_bound', /home/frag/.cargo/registry/src/github.com-1ecc6299db9ec823/rapier3d-0.11.1/src/geometry/broad_phase_multi_sap/sap_axis.rs:55:13

[jcornaz]

I don't reproduce it yet.

Can you please provide more information? The exact commit at which you tried. What is your OS, rust version, and rendering backend?

Can you share the full call stack?

Don't hesitate to provide any additional information you can think of.

[fgadaleta]

I made the ball collide with the ground and it crashes
Please find it here https://github.com/fgadaleta/herontest

[jcornaz]

I see here that you are using the 3d version.

But that example is a 2d example that creates collision shapes without any depth:

• https://github.com/fgadaleta/herontest/blob/main/src/main.rs#L37
• https://github.com/fgadaleta/herontest/blob/main/src/main.rs#L63

And rapier (not heron) crashes when the collision shape has a volume <= 0.

To solve your problem you can either:

• Use non-zero depth for the collision shapes
• Use the 2d feature flag instead of the 3d

[jcornaz]

I leave this issue open for discussion about how we could improve the situation.

On top of my head I think we could:

• ask rapier if it would be possible to not crash for empty volumes
• fail faster, when the shape is created, rather than when it collides
• force the user to deal with shape creation failure by having the factory methods return a Result<CollisionShape, Error>
• document better and warn the user about this limitation

[fgadaleta]

That also happens in 3D where there should be a volume already. For the record, this crashes too:

                    commands
                    .entity(entity)
                    .insert_bundle((transform, GlobalTransform::default()))
                    .insert(RigidBody::Dynamic)
                    .insert(CollisionShape::Sphere { radius: 2.7 })
                    .insert(PhysicMaterial {
                        restitution: 0.7,
                        density: 1.0,
                        ..Default::default()
                    })
                    .insert(CollisionLayers::new(Layer::Player, Layer::Player))
                    .insert(Velocity::from(Vec2::X * 300.0)
                            .with_angular(AxisAngle::new(Vec3::Y, -3.14)))
                    .insert(Drone);

[jcornaz]

That also happens in 3D where there should be a volume already. For the record, this crashes too:

This is only the ball, you also need to give a depth to the ground.

[fgadaleta]

I see here that you are using the 3d version.

But that example is a 2d example that creates collision shapes without any depth:

* https://github.com/fgadaleta/herontest/blob/main/src/main.rs#L37

* https://github.com/fgadaleta/herontest/blob/main/src/main.rs#L63

And rapier (not heron) crashes when the collision shape has a volume <= 0.

To solve your problem you can either:

* Use non-zero depth for the collision shapes

* Use the `2d` feature flag instead of the `3d`

you are right. Changing flag to 2d does not crash and it actually works (the green ball crashes but in a good way lol)

[fgadaleta]

In my example I spawn a dynamic body like so:

                    commands
                    .entity(entity)
                    .insert_bundle((transform, GlobalTransform::default()))
                    .insert(RigidBody::Dynamic)
                    .insert(CollisionShape::Cuboid {
                        half_extends: Vec3::new(1., 1., 1.),
                        border_radius: Some(1.),
                    })
                    .insert(PhysicMaterial {
                        restitution: 0.7,
                        density: 1.0,
                        ..Default::default()
                    })
                    .insert(CollisionLayers::new(Layer::Player, Layer::Player))
                    .insert(Velocity::from(Vec2::X * 300.0)
                            .with_angular(AxisAngle::new(Vec3::Y, -3.14)))
                    .insert(Drone);

and all the rest is static, like so:

                commands
                .entity(entity)
                .insert(RigidBody::Static)
                .insert(CollisionShape::Cuboid {
                    half_extends: Vec3::new(1., 1., 1.),
                    border_radius: Some(1.),
                })
                .insert(PhysicMaterial {
                    restitution: 30.,
                    friction: 1.0,
                    density: 100.0,
                    ..Default::default()
                })
                .insert(CollisionLayers::new(Layer::World, Layer::World))
                ;

[fgadaleta]

That also happens in 3D where there should be a volume already. For the record, this crashes too:

This is only the ball, you also need to give a depth to the ground.

    // The ground
    let size = Vec2::new(1000.0, 50.0);
    commands
        // Spawn a bundle that contains at least a `GlobalTransform`
        .spawn_bundle(SpriteBundle {
            sprite: Sprite {
                color: Color::WHITE,
                custom_size: Some(size),
                ..Default::default()
            },
            transform: Transform::from_translation(Vec3::new(0.0, -300.0, 0.0)),
            ..Default::default()
        })
        // Make it a rigid body
        .insert(RigidBody::Static)
        // Attach a collision shape
        .insert(CollisionShape::Cuboid {
            half_extends: size.extend(2.5) / 2.0,
            border_radius: None,
        })
        // Define restitution (so that it bounces)
        .insert(PhysicMaterial {
            restitution: 0.5,
            ..Default::default()
        });

    // The Ball
    let size = Vec2::new(30.0, 30.0);
    commands
        // Spawn a bundle that contains at least a `GlobalTransform`
        .spawn_bundle(SpriteBundle {
            sprite: Sprite {
                color: Color::GREEN,
                custom_size: Some(size),
                ..Default::default()
            },
            transform: Transform::from_translation(Vec3::new(-400.0, 200.0, 0.0)),
            ..Default::default()
        })
        // Make it a rigid body
        .insert(RigidBody::Dynamic)
        // Attach a collision shape
        .insert(CollisionShape::Cuboid {
            half_extends: size.extend(2.5) / 2.0,
            border_radius: None,
        })
        // Add an initial velocity. (it is also possible to read/mutate this component later)
        .insert(Velocity::from(Vec2::Y * -300.0).with_angular(AxisAngle::new(Vec3::Z, -PI)))
        // Define restitution (so that it bounces)
        .insert(PhysicMaterial {
            restitution: 0.7,
            ..Default::default()
        });

Collision is logged but ball disappears from screen (without actually colliding).
Using feature = ['3d'] here
2d in Cargo.toml works better (kinda)

[jcornaz]

Collision is logged but ball disappears from screen (without actually colliding).

Due to the fast angular velocity, the body gets moved along the z-axis. I am not sure of the exact reason, but that is probably due to f32 imprecision in rapier's matrix multiplications.

Nevertheless, it does not crash. And if you remove the angular velocity or increase the depth of the ground it interacts correctly. Though it will always look strange, because these are 2d sprites allowed to move and rotate along the z-axis

And anyway, the demo is a 2d example, so I think it is pointless to try making it good in 3d. Though, I acknowledge, that we should clarify that the demo is not meant to run as-is in 3d.

[fgadaleta]

Collision is logged but ball disappears from screen (without actually colliding).

Due to the fast angular velocity, the body gets moved along the z-axis. I am not sure of the exact reason, but that is probably due to f32 imprecision in rapier's matrix multiplications.

Nevertheless, it does not crash. And if you remove the angular velocity or increase the depth of the ground it interacts correctly. Though it will always look strange, because these are 2d sprites allowed to move and rotate along the z-axis

And anyway, the demo is a 2d example, so I think it is pointless to try making it good in 3d. Though, I acknowledge, that we should clarify that the demo is not meant to run as-is in 3d.

you are right. The demo is meant to be a 2d.
In my other reply I have been mentioning the 3d scenario, in which I have exactly the same problem.
Apologies for the confusion

[jcornaz]

In my other reply I have been mentioning the 3d scenario, in which I have exactly the same problem.

Can you please provide more information? At least a full reproducer, and the full stack trace you get?

[fgadaleta]

Absolutely.
Check https://gitlab.com/fgadaleta/bevy_experiment (gltf included from LFS)

If you just cargo run you will see it crashes.
If you change src/world/level1.rs:1148 to RigidBody::Static it will run.

Let me know if there's something missing as this is a repo to reproduce the error only

[bit-garden]

We should have a note encouraging to check Rapiers common mistakes article, or a friendlier way to hint to what's wrong. this had the answer to start with. A 3d object with 0 in one dimension has 0 mass/volume.