avocado-old/packages/physics/matter/body.js

import {Composite, Bodies, Body as MatterBody, Bounds, Vertices} from 'matter-js';

import {Vector} from '@avocado/math';
import {
  ShapeList,
  CircleShape,
  PolygonShape,
  RectangleShape,
} from '@avocado/physics';

import {AbstractBody} from '../abstract/body';

// Trick matter into not needing decomp for our convex polygons.
const g = typeof window !== 'undefined' ? window : typeof global !== 'undefined' ? global : undefined;
if (g) {
  g.decomp = require('poly-decomp');
}

const SCALE = 1;

export class Body extends AbstractBody {

  static collisionCategory(group) {
    if (!('filterCategoryBit' in this)) {
      this.filterCategoryBit = 0;
    }
    if (!('filterCategories' in this)) {
      this.filterCategories = {};
    }
    if (!this.filterCategories[group]) {
      this.filterCategories[group] = 1 << this.filterCategoryBit;
      this.filterCategoryBit += 1;
    }
    return this.filterCategories[group];
  }

  static lookupBody(matterBody) {
    if (this.bodies) {
      return this.bodies.get(matterBody);
    }
  }

  static associateBody(matterBody, avocadoBody) {
    if (!this.bodies) {
      this.bodies = new Map();
    }
    this.bodies.set(matterBody, avocadoBody);
  }

  constructor(shape) {
    super(shape);
    [
      this.matterBody,
      this.origin,
      this.position,
    ] = this.constructor.bodyFromShape(shape);
    this.constructor.associateBody(this.matterBody, this);
  }

  get aabb() {
    const bounds = this.matterBody.bounds;
    return [
      bounds.min.x,
      bounds.min.y,
      bounds.max.x - bounds.min.x,
      bounds.max.y - bounds.min.y,
    ].map((p) => p * SCALE);
  }

  applyForce(force) {
    force = Vector.scale(force, 1 / SCALE);
    const [x, y] = force;
    MatterBody.applyForce(this.matterBody, this.matterBody.position, {x, y});
  }

  applyImpulse(impulse, elapsed) {
    impulse = Vector.scale(impulse, 1 / SCALE);
    impulse = Vector.scale(impulse, elapsed);
    const [x, y] = impulse;
    MatterBody.translate(this.matterBody, {x, y});
  }

  static bodyFromShape(shape) {
    const shapePosition = Vector.scale(shape.position, 1 / SCALE);
    if (shape instanceof ShapeList) {
      const children = [];
      for (const child of shape) {
        const [body, position, origin] = this.bodyFromShape(child);
        const [x, y] = Vector.add(Vector.scale(position, 1 / SCALE), origin);
        MatterBody.setPosition(body, {x, y});
        children.push(body);
      }
      const body = MatterBody.create({parts: children});
      const {x, y} = body.position;
      return [body, shapePosition, Vector.scale([x, y], SCALE)];
    }
    else if (shape instanceof RectangleShape) {
      const [width, height] = Vector.scale(shape.size, 1 / SCALE);
      const body = Bodies.rectangle(0, 0, width, height);
      return [body, shapePosition, [0, 0]];
    }
    else if (shape instanceof CircleShape) {
      const body = Bodies.circle(0, 0, shape.radius / SCALE);
      return [body, shapePosition, [0, 0]];
    }
    else if (shape instanceof PolygonShape) {
      const vectors = [];
      for (let vertice of shape) {
        const[x, y] = Vector.scale(vertice, 1 / SCALE)
        vectors.push({x, y});
      }
      const {x, y} = Vertices.centre(vectors);
      const body = Bodies.fromVertices(0, 0, vectors);
      return [body, shapePosition, [x, y]];
    }
  }

  get position() {
    const {x, y} = this.matterBody.position;
    return Vector.scale(Vector.sub([x, y], this.origin), SCALE);
  }

  set position(position) {
    position = Vector.scale(position, 1 / SCALE);
    position = Vector.add(position, this.origin);
    if (Vector.equalsClose(this.position, position)) {
      return;
    }
    const [x, y] = position;
    MatterBody.setPosition(this.matterBody, {x, y});
  }

  setCollision(category, mask, group = 0) {
    MatterBody.set(this.matterBody, 'collisionFilter', {
      category,
      group,
      mask,
    });
  }

  setCollisionForEntity(entity) {
    if (entity.is('collider')) {
      const ctor = this.constructor;
      const category = ctor.collisionCategory(entity.collisionGroup);
      let mask = 0;
      for (const group of entity.collidesWithGroups) {
        mask = mask | ctor.collisionCategory(group);
      }
      this.setCollision(category, mask);
    }
    else {
      this.setCollision(0, 0, -1);
    }
  }

  get static() {
    return this.matterBody.isStatic;
  }

  set static(isStatic) {
    MatterBody.setStatic(this.matterBody, isStatic);
  }

  get vertices() {
    const vertices = [];
    for (const {x, y} of this.matterBody.vertices) {
      vertices.push(Vector.scale([x, y], SCALE));
    }
    return vertices;
  }

}