threefiz/src/World.ts

Implementation of a physics engine based on the [Three.js](https://github.com/mrdoob/three.js) library.

import { Vector3 } from "three";
import RigidBody from "./RigidBody";
import AABBTree from "./AABBTree/AABBTree";

class World {
  private gravity: Vector3;

  constructor(gravity: Vector3 = new Vector3(0, -9.8, 0)) {
    this.gravity = gravity;
  }

  setGravity(gravity: Vector3): void {
    this.gravity = gravity;
  }

  private applyGravity(object: RigidBody, dT: number): void {
    object.setVelocity((old) =>
      old.add(this.gravity.clone().multiplyScalar(dT))
    );
  }

  updateObjects(objects: RigidBody[], AABBTree: AABBTree, dT: number): void {
    objects.forEach((object, id) => {
      if (!object.isStatic) object.needsUpdate = true;
      if (object.needsUpdate) {
        this.applyGravity(object, dT);
        object.updatePosition(dT);
        object.updateRotation(dT);
        object.mesh.updateMatrix();
        object.mesh.updateMatrixWorld();
        if (object.isMoved) {
          object.updateAABB();
          object.updateCollider();
        }
        AABBTree.update(id, object.aabb);
        object.needsUpdate = false;
      }
      object.debug.update();
    });
  }
}

export default World;