Physics

Abstraction for physics simulation.

Gravity sources

There are directional and point gravity sources available. Directional gravity applies to all bodies, while point sources affects ones that are within their defined radius:

using World world = new();
DirectionalGravity globalGravity = new(world, -Vector3.UnitY);

float radius = 700000f;
Vector3 position = new(0, 0, 0);
PointGravity planetaryGravity = new(world, position, radius);

Physics bodies

Entities that would like to have collisions simulated, or velocities advanced are considered bodies. Where they contain an IsBody component and are also transform entities:

//a ball that will fall
SphereShape ballShape = new(world, 0.5f);
Body ballBody = new(world, ballShape, IsBody.Type.Dynamic);
Transform ballTransform = ballBody;
ballTransform.Position = new(0, 5, 0);
ballBody.Velocity = new(0, 4, 0);

//onto a static floor
CubeShape floorShape = new(world, 0.5f, 0.5f, 0.5f);
Body floorBody = new(world, floorShape, IsBody.Type.Static);
Transform floorTransform = floorBody;
floorTransform.Scale = new(100, 1, 100);

TimeSpan time = default;
while (time.TotalSeconds < 5f)
{
    TimeSpan delta = TimeSpan.FromSeconds(0.2f);
    world.Submit(new PhysicsUpdate(delta));
    world.Poll();
    time += delta;
}

Raycasts

Raycasts are dispatched by submitting a Raycast event, which will be fulfilled at the end of a PhysicsUpdate event:

Raycast raycast = new(new(0, 10, 0), new(0, -1, 0), new(&OnHit));
world.Submit(raycast);

[UnmanagedCallersOnly]
private unsafe static void OnHit(World world, Raycast raycast, void* hitsPointer, int hitCount)
{
    Span<RaycastHit> hits = new(hitsPointer, hitCount);
    foreach (RaycastHit hit in hits)
    {
        uint entityHit = hit.entity;
        Vector3 point = hit.point;
        Vector3 normal = hit.normal;
    }
}

The constructor can accept an arbitrary identifier value which can be used to differentiate between multiple raycasts