oden/game/actor.ts

import { load_texture } from "./assets";
import { btn, Button } from "./input";
import { Vec2, new_v2, vadd, vsub, vnorm, vmul } from "./vector";
import { spr, use_texture, Texture } from "./graphics";
import { has_collision, Level } from "./level";

export interface ActorProps {
  id: string;

  cx: number;
  cy: number;
  xr: number;
  yr: number;

  position: Vec2;
  velocity: Vec2;
  friction: number;
  collide_radius: number;
}

export function new_actor_props(
  id: string,
  position: Vec2,
  collide_radius: number
): ActorProps {
  const cx = Math.trunc(position.x / 16);
  const cy = Math.trunc(position.y / 16);
  const xr = (position.x - cx * 16) / 16;
  const yr = (position.y - cy * 16) / 16;

  return {
    cx,
    cy,
    xr,
    yr,
    velocity: new_v2(0),
    friction: 0.7,
    id,
    position,
    collide_radius,
  };
}

export class Actor {
  type: ActorType;
  props: ActorProps;

  constructor(type: ActorType, props: ActorProps) {
    this.type = type;
    this.props = props;
  }

  update() {}

  // IDEAS: Make gameplay logic at 30fps and render updates at 60fps? Does
  //        this mean we do some "update" in render?
  //
  // TODO: Update physics in a better kind of way rather than an object call.
  update_physics(level: Level) {
    // This is very nice: https://deepnight.net/tutorial/a-simple-platformer-engine-part-1-basics/
    // Apply friction to velocity and zero if we're close enough to zero.
    const props = this.props;
    const velocity = vmul(props.velocity, props.friction);
    if (Math.abs(velocity.x) < 0.01) {
      velocity.x = 0;
    }
    if (Math.abs(velocity.y) < 0.01) {
      velocity.y = 0;
    }

    let cx = props.cx;
    let cy = props.cy;

    let xr = props.xr;
    let yr = props.yr;

    const steps = Math.ceil(
      (Math.abs(velocity.x) + Math.abs(velocity.y)) / 0.33
    );
    if (steps > 0) {
      for (let n = 0; n < steps; n++) {
        xr += velocity.x / steps;
        if (velocity.x != 0) {
          // Physics and whatnot.
          if (xr >= 0.7 && has_collision(level, cx + 1, cy)) {
            xr = 0.7;
            velocity.x = 0;
          }
          if (xr <= 0.3 && has_collision(level, cx - 1, cy)) {
            xr = 0.3;
            velocity.x = 0;
          }
        }
        while (xr > 1) {
          xr--;
          cx++;
        }
        while (xr < 0) {
          xr++;
          cx--;
        }

        yr += velocity.y / steps;
        if (velocity.y != 0) {
          if (yr >= 0.4 && has_collision(level, cx, cy + 1)) {
            yr = 0.4;
            velocity.y = 0;
          }
          if (yr <= 0.1 && has_collision(level, cx, cy - 1)) {
            yr = 0.1;
            velocity.y = 0;
          }
        }
        while (yr > 1) {
          cy += 1;
          yr -= 1;
        }
        while (yr < 0) {
          cy -= 1;
          yr += 1;
        }
      }
    }

    // TODO: Entity collision detection

    const new_position = new_v2((cx + xr) * 16, (cy + yr) * 16);

    props.cx = cx;
    props.cy = cy;
    props.xr = xr;
    props.yr = yr;
    props.velocity = velocity;
    props.position = new_position;
  }

  draw(_clock: number) {}

  bonk(_other: Actor) {}
}

const robo_info = {
  anchor: new_v2(16, 16), // Distance from upper-left of sprite.
  bounds: new_v2(32), // Width/height of sprite.
  sprite: "./bot.png",
  animations: [
    { start: 0, length: 1, speed: 20 },
    { start: 1, length: 4, speed: 8 },
  ],
};

export class Robo extends Actor {
  bot_sprite: Texture | undefined = undefined;

  constructor(props: ActorProps) {
    super("robo", props);
    load_texture(robo_info.sprite).then((texture) => {
      this.bot_sprite = texture;
    });
  }

  update() {
    // Acceleration from input
    let a = new_v2(0);
    if (btn(Button.Up)) {
      a.y -= 1;
    }
    if (btn(Button.Down)) {
      a.y += 1;
    }
    if (btn(Button.Left)) {
      a.x -= 1;
    }
    if (btn(Button.Right)) {
      a.x += 1;
    }
    vnorm(a);
    this.props.velocity = vadd(this.props.velocity, vmul(a, 0.07));
  }

  draw(clock: number) {
    if (this.bot_sprite != undefined) {
      use_texture(this.bot_sprite);

      const vel = this.props.velocity;
      const moving = vel.x != 0 || vel.y != 0;
      const anim = robo_info.animations[moving ? 1 : 0];

      const { x: w, y: h } = robo_info.bounds;
      const { x, y } = vsub(this.props.position, robo_info.anchor);

      const frame = (anim.start + ((clock / anim.speed) % anim.length)) >> 0;
      spr(x, y, w, h, frame * w, 0, 32, 32);

      // color(0, 0, 0, 0);
      // stroke(0, 0, 0, 1);
      // circle(this.props.position.x, this.props.position.y, 8, 1);
    }
  }
}

const ACTOR_TABLE = {
  robo: (s: ActorProps) => new Robo(s),
};

export type ActorType = keyof typeof ACTOR_TABLE;

export function is_actor_type(type: string): type is ActorType {
  return ACTOR_TABLE.hasOwnProperty(type);
}

export function spawn_actor(type: ActorType, props: ActorProps): Actor {
  return ACTOR_TABLE[type](props);
}