symtropy-physics

N-dimensional rigid body physics with GJK+EPA collision detection. Zero heap allocation in the hot path.

use symtropy_physics::PhysicsWorld;
use symtropy_math::{Point, Sphere};
use nalgebra::SVector;

// Create a 3D world with gravity
let mut world = PhysicsWorld::<3>::new(SVector::from([0.0, -9.81, 0.0]));

// Add spheres
let a = world.add_sphere(Point::new([0.0, 10.0, 0.0]), 1.0, 1.0);
let b = world.add_sphere(Point::new([0.0, 0.0, 0.0]), 1.0, 1.0);

// Step the simulation
for _ in 0..100 {
    world.step(0.016);
}

// Spheres collided and bounced

Features

• GJK intersection test — 102ns for sphere×sphere (benchmarked)
• EPA penetration depth — accurate contact normals for 2D and 3D
• Coulomb friction — tangential impulse clamped by μ×j_n
• Body sleeping — deactivate near-stationary bodies, wake on collision
• Collision events — CollisionEvent<D> for game logic callbacks
• PhysicsCallback trait — inject consciousness or custom force modulation into the physics step
• Constraints — distance constraints (more coming)
• Const-generic dimensions — PhysicsWorld<2>, PhysicsWorld<3>, PhysicsWorld<4>
• Zero heap — GJK simplex uses ArrayVec, bivectors use [f64; 6]
• WASM compatible

Benchmarks

PhysicsCallback — Custom Force Modulation

use symtropy_physics::{PhysicsCallback, CollisionEvent, BodyHandle};

struct MyCallback;
impl PhysicsCallback<3> for MyCallback {
    fn modulate_impulse(&self, impulse: f64, point: &SVector<f64, 3>) -> f64 {
        impulse * 0.5 // Dampen all collisions by 50%
    }
    // ... other methods
}

world.step_with_callback(0.016, &mut MyCallback);

Part of the Symtropy consciousness-physics engine.