Function applySpringStep

src/llm/Camera.ts:186–200

(pos: Vec3, target: Vec3, vel: Vec3 | null | undefined, dt: number, config: ISpringConfig)

}

export function applySpringStep(pos: Vec3, target: Vec3, vel: Vec3 | null | undefined, dt: number, config: ISpringConfig) {
    // default to critically damped
    let friction = config.friction ?? 2 * Math.sqrt(config.mass * config.tension);
    let dtS = dt / 1000;
    vel = vel ?? new Vec3();
    let dist = pos.sub(target);
    let springExtra = dist.lenSq() === 0.0 ? new Vec3() : dist.normalize().mul(config.extra ?? 0);
    let springF = (dist.add(springExtra)).mul(-config.tension);
    let dampF = vel.mul(-friction);
    let accel = springF.add(dampF).mul(1.0 / config.mass);

    vel = vel.add(accel.mul(dtS));
    pos = pos.add(vel.mul(dtS));
    return { pos, vel };
}