silphius/app/ecs/components/collider.js

import Component from '@/ecs/component.js';
import {distance, intersects, transform} from '@/util/math.js';

import vector2d from './helpers/vector-2d';

export default class Collider extends Component {
  instanceFromSchema() {
    const {ecs} = this;
    return class ColliderInstance extends super.instanceFromSchema() {
      $$aabb = {x0: Infinity, x1: -Infinity, y0: Infinity, y1: -Infinity};
      $$aabbs = [];
      $$collisionStart;
      $$collisionEnd;
      $$intersections = new Map();
      get aabb() {
        const {Position: {x: px, y: py}} = ecs.get(this.entity);
        return {
          x0: this.$$aabb.x0 + px,
          x1: this.$$aabb.x1 + px,
          y0: this.$$aabb.y0 + py,
          y1: this.$$aabb.y1 + py,
        };
      }
      get aabbs() {
        const {Position: {x: px, y: py}} = ecs.get(this.entity);
        const aabbs = [];
        for (const aabb of this.$$aabbs) {
          aabbs.push({
            x0: aabb.x0 + px,
            x1: aabb.x1 + px,
            y0: aabb.y0 + py,
            y1: aabb.y1 + py,
          })
        }
        return aabbs;
      }
      endIntersections(other, intersections) {
        const otherEntity = ecs.get(other.entity);
        const thisEntity = ecs.get(this.entity);
        for (const intersection of intersections) {
          const [body, otherBody] = [
            intersection.entity.bodies[intersection.i],
            intersection.other.bodies[intersection.j],
          ];
          if (this.$$collisionEnd) {
            const script = this.$$collisionEnd.clone();
            script.context.other = otherEntity;
            script.context.pair = [body, otherBody];
            thisEntity.Ticking.add(script.ticker());
          }
          if (other.$$collisionEnd) {
            const script = other.$$collisionEnd.clone();
            script.context.other = thisEntity;
            script.context.pair = [otherBody, body];
            otherEntity.Ticking.add(script.ticker());
          }
        }
        this.$$intersections.delete(other);
        other.$$intersections.delete(this);
      }
      checkCollision(other) {
        const otherEntity = ecs.get(other.entity);
        const thisEntity = ecs.get(this.entity);
        const intersections = this.intersectionsWith(other);
        const activeIntersections = this.$$intersections.get(other) || new Set();
        if (0 === intersections.length) {
          // had none; have none
          if (0 === activeIntersections.size) {
            return;
          }
          this.endIntersections(other, intersections);
          return;
        }
        for (const intersection of intersections) {
          // new pair - start
          const [body, otherBody] = [
            intersection.entity.bodies[intersection.i],
            intersection.other.bodies[intersection.j],
          ];
          let hasMatchingIntersection = false;
          for (const activeIntersection of activeIntersections) {
            if (
              (
                activeIntersection.entity === intersection.entity
                && activeIntersection.other === intersection.other
                && activeIntersection.i === intersection.i
                && activeIntersection.j === intersection.j
              )
              || (
                activeIntersection.entity === intersection.other
                && activeIntersection.other === intersection.entity
                && activeIntersection.i === intersection.j
                && activeIntersection.j === intersection.i
              )
            ) {
              hasMatchingIntersection = true;
              break;
            }
          }
          if (!hasMatchingIntersection) {
            if (this.$$collisionStart) {
              const script = this.$$collisionStart.clone();
              script.context.other = otherEntity;
              script.context.pair = [body, otherBody];
              thisEntity.Ticking.add(script.ticker());
            }
            if (other.$$collisionStart) {
              const script = other.$$collisionStart.clone();
              script.context.other = thisEntity;
              script.context.pair = [otherBody, body];
              otherEntity.Ticking.add(script.ticker());
            }
            activeIntersections.add(intersection);
          }
          // undo restricted movement
          if (!body.unstoppable && otherBody.impassable) {
            const j = this.bodies.indexOf(body);
            const oj = other.bodies.indexOf(otherBody);
            const aabb = this.$$aabbs[j];
            const otherAabb = other.aabbs[oj];
            const {Position} = thisEntity;
            if (!intersects(
              {
                x0: aabb.x0 + Position.lastX,
                x1: aabb.x1 + Position.lastX,
                y0: aabb.y0 + Position.y,
                y1: aabb.y1 + Position.y,
              },
              otherAabb,
            )) {
              Position.x = Position.lastX
            }
            else if (!intersects(
              {
                x0: aabb.x0 + Position.x,
                x1: aabb.x1 + Position.x,
                y0: aabb.y0 + Position.lastY,
                y1: aabb.y1 + Position.lastY,
              },
              otherAabb,
            )) {
              Position.y = Position.lastY
            }
            else {
              Position.x = Position.lastX
              Position.y = Position.lastY
            }
            break;
          }
        }
        if (activeIntersections.size > 0) {
          this.$$intersections.set(other, activeIntersections);
          other.$$intersections.set(this, activeIntersections);
        }
      }
      closest(aabb) {
        const entity = ecs.get(this.entity);
        return Array.from(ecs.system('Colliders').within(aabb))
          .filter((other) => other !== entity)
          .sort(({Position: l}, {Position: r}) => {
            return distance(entity.Position, l) > distance(entity.Position, r) ? -1 : 1;
          });
      }
      destroy() {
        for (const [other] of this.$$intersections) {
          other.$$intersections.delete(this);
        }
        this.$$intersections.clear();
      }
      intersectionsWith(other) {
        const {aabb, aabbs} = this;
        const {aabb: otherAabb, aabbs: otherAabbs} = other;
        const intersections = [];
        if (!intersects(aabb, otherAabb)) {
          return intersections;
        }
        for (const i in aabbs) {
          const aabb = aabbs[i];
          for (const j in otherAabbs) {
            const otherAabb = otherAabbs[j];
            // todo accuracy
            if (intersects(aabb, otherAabb)) {
              intersections.push({
                entity: this,
                other,
                i,
                j,
              });
            }
          }
        }
        return intersections;
      }
      isWithin(query) {
        const {aabb, aabbs} = this;
        if (!intersects(aabb, query)) {
          return false;
        }
        for (const aabb of aabbs) {
          if (intersects(aabb, query)) {
            return true;
          }
        }
        return false;
      }
      updateAabbs() {
        this.$$aabb = {x0: Infinity, x1: -Infinity, y0: Infinity, y1: -Infinity};
        this.$$aabbs = [];
        const {bodies} = this;
        const {Direction: {direction = 0} = {}} = ecs.get(this.entity);
        for (const body of bodies) {
          let x0 = Infinity, x1 = -Infinity, y0 = Infinity, y1 = -Infinity;
          for (const point of transform(body.points, {rotation: direction})) {
            const {x, y} = point;
            if (x < x0) x0 = x;
            if (x < this.$$aabb.x0) this.$$aabb.x0 = x;
            if (x > x1) x1 = x;
            if (x > this.$$aabb.x1) this.$$aabb.x1 = x;
            if (y < y0) y0 = y;
            if (y < this.$$aabb.y0) this.$$aabb.y0 = y;
            if (y > y1) y1 = y;
            if (y > this.$$aabb.y1) this.$$aabb.y1 = y;
          }
          this.$$aabbs.push({
            x0: x0 > x1 ? x1 : x0,
            x1: x0 > x1 ? x0 : x1,
            y0: y0 > y1 ? y1 : y0,
            y1: y0 > y1 ? y0 : y1,
          });
        }
      }
    }
  }
  async load(instance) {
    instance.updateAabbs();
    // heavy handed...
    if ('undefined' !== typeof window) {
      return;
    }
    instance.$$collisionEnd = await this.ecs.readScript(
      instance.collisionEndScript,
      {
        ecs: this.ecs,
        entity: this.ecs.get(instance.entity),
      },
    );
    instance.$$collisionStart = await this.ecs.readScript(
      instance.collisionStartScript,
      {
        ecs: this.ecs,
        entity: this.ecs.get(instance.entity),
      },
    );
  }
  static properties = {
    bodies: {
      type: 'array',
      subtype: {
        type: 'object',
        properties: {
          impassable: {type: 'uint8'},
          points: {
            type: 'array',
            subtype: vector2d('int16'),
          },
          tags: {
            type: 'array',
            subtype: {type: 'string'},
          },
          unstoppable: {type: 'uint8'},
        },
      },
    },
    collisionEndScript: {type: 'string'},
    collisionStartScript: {type: 'string'},
  };
}