redox/src/Particles.ts

import { Ctx, CANVAS_WIDTH, CANVAS_HEIGHT } from "./MainDraw.js";
import Particle, { colorFromCharge } from "./classes/Particle.js";
import Vector from "./classes/Vector.js";
import { circle } from "./Shapes.js";
import { LeftClickAction } from "./ui/main/UI.js";

let particles: Particle[] = [];
let mouseProperties: MouseProperties = {
  charge: 0,
  strength: 1,
  pos: new Vector(),
};

export function initParticles() {
  particles = [];
  const chargeToMass = [1, 1, 1];

  for (let i = 0; i < 200; i++) {
    const charge = Math.random() < 0.3 ? 0 : Math.random() < 0.5 ? 1 : -1;
    particles.push(
      new Particle(
        new Vector(
          Math.random() * (CANVAS_WIDTH - 100) + 50,
          Math.random() * (CANVAS_HEIGHT - 100) + 50
        ),
        charge,
        chargeToMass[charge + 1]
      )
    );
  }
}

interface MouseProperties {
  charge: number;
  strength: number;
  pos: Vector;
}

export function getMousePosition(): Vector {
  return mouseProperties.pos;
}

export function invokeDefaultLeftClickAction(
  action: LeftClickAction,
  mousePos: Vector
) {
  particles = action(mousePos, particles);
}

export function changeMouseProperties(
  transformer: (old: MouseProperties) => MouseProperties
) {
  mouseProperties = transformer(mouseProperties);
}

export function drawParticles(ctx: Ctx) {
  particles.forEach((p) => p.draw(ctx));
  circle(
    ctx,
    mouseProperties.pos.x,
    mouseProperties.pos.y,
    5,
    colorFromCharge(mouseProperties.charge)
  );
}

export function updateParticles() {
  calculateChargedForces();
  particles.forEach((p) => p.update());
}

function calculateChargedForces() {
  for (let i = 0; i < particles.length; i++) {
    const particle = particles[i];
    if (particle.charge !== 0) {
      for (let j = i + 1; j < particles.length; j++) {
        const innerParticle = particles[j];
        if (innerParticle.charge !== 0) {
          const dist = particle.position.distance(innerParticle.position);
          if (dist < 300 && dist > 0) {
            const f1 = innerParticle.position
              .sub(particle.position)
              .scale(0.5 / dist ** 2);
            /*
                        that does not actually work because the world does not work like that
                       but there is probably something missing here if the charges aren't equal
                       .scale(Math.max(Math.abs(particle.charge), Math.abs(innerParticle.charge))
                       / Math.min(Math.abs(particle.charge), Math.abs(innerParticle.charge)));
                       */
            if (particle.charge === innerParticle.charge) {
              particle.applyForce(f1.negated());
              innerParticle.applyForce(f1);
            } else {
              particle.applyForce(f1);
              innerParticle.applyForce(f1.negated());
            }
          }
        }
      }

      // mouse
      const dist = particle.position.distance(mouseProperties.pos);
      if (mouseProperties.charge !== 0 && dist < 10000 && dist > 0.3) {
        const f1 = mouseProperties.pos
          .sub(particle.position)
          .scale(0.5 / dist ** 2)
          .scale(mouseProperties.strength * 5);
        if (particle.charge === mouseProperties.charge) {
          particle.applyForce(f1.negated());
        } else {
          particle.applyForce(f1);
        }
      }
    }
  }
}