orbit-camera

A third-person orbit/follow camera for action-adventure games, extracted from a shared pattern across several games (magic-journey, bad-fates, oneira-woods, cyborg-evolution, ruffy-wonder, open-world-minigolf).

The camera orbits a focus point that smoothly follows a target. Yaw and pitch are set directly; the orbit distance scales with pitch and can be zoomed. Focus and distance interpolate frame-rate independently. An optional clipping pass pulls the camera in when geometry blocks the view.

Design

• No matrix dependency. view() returns eye, focus, up and projection parameters. Build the view-projection matrix with whatever the renderer uses.
• Backend-agnostic clipping. clip takes any Clip implementor. Enable the collide-mesh feature for a ready-made impl on collide_mesh::CollisionWorld.
• Fully configurable. Every constant (pitch range, distances, smoothing, field of view, clip margins) lives in CameraConfig. Default matches a Zelda-style feel.

Built on ga3::Vector<f32>.

Example

use ga3::Vector;
use orbit_camera::OrbitCamera;

let mut camera = OrbitCamera::new(player_position);

// per frame:
camera.rotate([stick.x * sensitivity, stick.y * sensitivity]);
camera.zoom(scroll);
camera.follow(player_position, timestep);
camera.clip(&world); // requires the `collide-mesh` feature, or impl Clip yourself

let view = camera.view();
let view_projection = perspective(view.field_of_view, aspect, view.near_plane, view.far_plane)
    * look_at(view.eye, view.focus, view.up);

// move the player relative to the camera:
let basis = camera.basis();
let movement = basis.forward * input.y + basis.right * input.x;

Features

• collide-mesh — implement Clip for collide_mesh::CollisionWorld.

AI-coding friendliness

• Pure-function camera state: view()/basis()/eye() have no side effects.
• No implicit matrix convention baked in — the consumer owns the projection.
• Clipping is decoupled behind the one-method Clip trait, so the camera has no hard dependency on any collision backend.