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

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

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

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

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.origin, this.matterBody] = 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,
    ];
  }

  applyForce(force) {
    MatterBody.applyForce(
      this.matterBody,
      this.matterBody.position,
      {
        x: force[0],
        y: force[1],
      }
    );
  }

  applyImpulse(impulse, elapsed) {
    impulse = Vector.scale(impulse, elapsed);
    MatterBody.translate(this.matterBody, {
      x: impulse[0],
      y: impulse[1],
    });
  }

  static bodyFromShape(shape) {
    if (shape instanceof RectangleShape) {
      const body = Bodies.rectangle(
        0,
        0,
        shape.width,
        shape.height,
      );
      return [shape.position, body];
    }
    else if (shape instanceof PolygonShape) {
      const vectors = [];
      for (const vertice of shape) {
        vectors.push({
          x: vertice[0],
          y: vertice[1],
        });
      }
      const centre = Vertices.centre(vectors);
      const body = Bodies.fromVertices(
        0,
        0,
        vectors,
      );
      const origin = Vector.add(
        shape.position,
        Vector.scale([centre.x, centre.y], 1),
      );
      return [origin, body];
    }
  }

  get position() {
    return [
      this.matterBody.position.x,
      this.matterBody.position.y,
    ];
  }

  set position(position) {
    position = Vector.add(position, this.origin);
    if (Vector.equalsClose(this.position, position)) {
      return;
    }
    MatterBody.setPosition(this.matterBody, {
      x: position[0],
      y: position[1],
    });
  }

  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([x, y]);
    }
    return vertices;
  }

}