humus-old/common/combat/emitter.js

import {Proton, TextNode} from '@avocado/graphics';

class DamageTextNode extends TextNode {

  constructor(damage) {
    const {amount} = damage;
    super(amount);
    this.damage = damage;
  }

  sizeInPx() {
    const {amount} = this.damage;
    // Big numbers are literally big.
    if (amount > 999) {
      return 12;
    }
    else if (amount > 99) {
      return 10;
    }
    else if (amount > 9) {
      return 8;
    }
    else {
      return 6;
    }
  }

  spanClassName() {
    const {damageSpec, isDamage} = this.damage;
    let className = super.spanClassName();
    className += ' affinity-' + damageSpec.affinity;
    if (isDamage) {
      className += ' is-damage';
    }
    else {
      className += ' is-healing';
    }
    return className;
  }

}

export class DamageEmitter {

  constructor() {
    const proton = new Proton();
    const emitter = new Proton.Emitter();
    proton.addEmitter(emitter);
    this.emitter = emitter;
    this.proton = proton;
  }

  addRenderer(renderer) {
    this.renderer = renderer;
    this.proton.addRender(this.renderer);
  }

  destroy() {
    this.proton.destroy();
  }

  emit(position, damage) {
    // BUGS
    const pz = new Proton.PointZone();
    pz.x = position[0];
    pz.y = -position[1];
    const initializers = [
      new Proton.Body(new DamageTextNode(damage)),
      new Proton.Position(pz),
      new Proton.Mass(1),
      new Proton.Life(2),
      new Proton.Velocity(
        new Proton.Span(50, 90),
        new Proton.Vector3D(0, 5, 0),
        27.5
      ),
    ];
    // Heh, bugs.
    const rot = new Proton.Rotate(0, 0, 0);
    rot.a = new Proton.Span(-.006, .006);
    const behaviors = [
      new Proton.Alpha(1, .25),
      new Proton.Scale(.8, 1.2),
      new Proton.Force(0, -0.5, 0),
      rot,
    ];
    this.emitter.createParticle(initializers, behaviors);
  }

  hasParticles() {
    return this.particleCount > 0;
  }

  get particleCount() {
    return this.emitter.particles.length;
  }

  tick(elapsed) {
    this.proton.tick(elapsed);
  }

}