unibutton/common/player.js

function distF(ent, target) {
    return ((ent.pos.x - target.pos.x) ** 2) + ((ent.pos.y - target.pos.y) ** 2)
}

function uuidv4() {
    return "#000000-000000".replace(/[018]/g, c =>
        (+c ^ crypto.getRandomValues(new Uint8Array(1))[0] & 15 >> +c / 4).toString(16)
    );
}

function Player(you, isPlayer) {
    let pos = { x: Math.random() * 5000 - 50, y: Math.random() * 5000 - 50 };
    let camera = { x: -pos.x, y: -pos.y };
    let vel = { x: 0, y: 0 };

    this.camera = camera;
    this.pos = pos;
    this.vel = vel;
    this.rot = 0;
    this.dir = 1;
    this.ticks = 0;

    this.health = 100;

    this.you = you || uuidv4();

    this.isPlayer = isPlayer;

    this.headCount = 0;
}

Player.prototype.bump = function () {
    let player = this;

    if (player.ticks < 10) {
        player.dir *= -1;
    }

    player.vel.x *= 0.3;
    player.vel.y *= 0.3;

    player.vel.x += Math.sin(player.rot) * 12;
    player.vel.y -= Math.cos(player.rot) * 12;

    player.ticks = 0;
}

Player.prototype.handleTick = function (game) {
    let { entities } = game;

    let ent = this;

    if (ent.health <= 0) return;

    ent.pos.x += ent.vel.x;
    ent.pos.y += ent.vel.y;

    ent.vel.x *= 0.9;
    ent.vel.y *= 0.9;

    ent.rot += 0.03 * ent.dir;
    ent.rot = ent.rot % (Math.PI * 10);

    ent.camera.x = -ent.pos.x * 0.1 + ent.camera.x * 0.9;
    ent.camera.y = -ent.pos.y * 0.1 + ent.camera.y * 0.9;

    ent.ticks++;

    for (let target of entities) {
        if (target.you == ent.you) continue;

        let dist = distF(ent, target);

        let dp = (Math.sin(ent.rot) * (ent.pos.x - target.pos.x))
            - (Math.cos(ent.rot) * (ent.pos.y - target.pos.y));

        dp /= Math.sqrt(dist + 0.1);

        if (Math.sqrt(dist) < 128 && 1 / dp < -0.2) {
            target.health--;

            if (target.health == 0) {
                ent.headCount++;
            }
        }
    }
}