bamling / amethyst-nphysics-example

nphysics Amethyst integration in Rust

amethyst-nphysics-example

Simple example "game" illustrating how an integration of nphysics into Amethyst could look like. This example uses the master version of Amethyst and has all the nphysics related logic abstracted away in a separate crate (game_physics).

Rust version: rustc 1.36.0-nightly (3991285f5 2019-04-25)

Running the example:

Clone the repository:

$ git clone https://github.com/bamling/amethyst-nphysics-example.git

Change into the checkout directory:

$ cd amethyst-nphysics-example

Execute Cargo:

$ cargo run

Roadmap:

• Allow multiple PhysicsColliders per Entity
• Allow PhysicsColliders without PhysicsBody
• Automatically apply margin to full Shape size
• Add more Shapes
• Add other debug shapes
• Expose channels for CollisionEvents and ProximityEvents
• Remove custom Isometry, Matrix and Point types
• Refactor body/collider Sytems
• Ray interferences to prevent tunneling issues*
• Custom GameData with separate dispatcher for movement/physics based Systems (executed during fixed_update(..))
• Clean up game_physics crate exports
• Add tests
• Introduce generic type parameters over f32
• Examples on how to use the crate
• Polishing, polishing, polishing...
• Build automation/CI
• Publish to crates.io (migrate repository for that?)

*Thanks to sebcrozet for the idea:

Well, you can cast a ray on the world using: https://www.nphysics.org/rustdoc/nphysics3d/world/struct.ColliderWorld.html#method.interferences_with_ray. The ray direction would be the player desired velocity, and the ray starting point would be right in front of the player in that direction. If interferences are found, then find the one with the smallest toi field: https://www.ncollide.org/rustdoc/ncollide3d/query/ray_internal/struct.RayIntersection.html#structfield.toi which is < 1.0. Then you take this toi (if it exists) and multiply it with the players' desired velocity. This will give you a new vector that is the velocity you actually want to apply to your player.

let point_in_front_of_the_player = desired_velocity.normalize() * (player_box_radius + 0.1) + player_center_position;
let ray = Ray::new(point_in_front_of_the_player, desired_velocity);
let toi = world.interferences_with_ray(ray, CollisionGroups::default()).fold(1.0, |a, inter| a.min(inter.1.toi));
let velocity_to_apply = desired_velocity * toi;