oneko2.js

// oneko.js: https://github.com/adryd325/oneko.js

(function oneko() {
    const nekoEl = document.createElement("div");
    let nekoPosX = 32;
    let nekoPosY = 32;
    let mousePosX = 0;
    let mousePosY = 0;
    let frameCount = 0;
    let idleTime = 0;
    let idleAnimation = null;
    let idleAnimationFrame = 0;
    const nekoSpeed = 10;
    const spriteSets = {
      idle: [[-3, -3]],
      alert: [[-7, -3]],
      scratchSelf: [
        [-5, 0],
        [-6, 0],
        [-7, 0],
      ],
      scratchWallN: [
        [0, 0],
        [0, -1],
      ],
      scratchWallS: [
        [-7, -1],
        [-6, -2],
      ],
      scratchWallE: [
        [-2, -2],
        [-2, -3],
      ],
      scratchWallW: [
        [-4, 0],
        [-4, -1],
      ],
      tired: [[-3, -2]],
      sleeping: [
        [-2, 0],
        [-2, -1],
      ],
      N: [
        [-1, -2],
        [-1, -3],
      ],
      NE: [
        [0, -2],
        [0, -3],
      ],
      E: [
        [-3, 0],
        [-3, -1],
      ],
      SE: [
        [-5, -1],
        [-5, -2],
      ],
      S: [
        [-6, -3],
        [-7, -2],
      ],
      SW: [
        [-5, -3],
        [-6, -1],
      ],
      W: [
        [-4, -2],
        [-4, -3],
      ],
      NW: [
        [-1, 0],
        [-1, -1],
      ],
    };

    function create() {
      nekoEl.id = "oneko";
      nekoEl.style.width = "32px";
      nekoEl.style.height = "32px";
      nekoEl.style.position = "fixed";
      nekoEl.style.pointerEvents = "none";
      nekoEl.style.backgroundImage = "url('./oneko.gif')";
      nekoEl.style.imageRendering = "pixelated";
      nekoEl.style.left = "16px";
      nekoEl.style.top = "16px";

      document.body.appendChild(nekoEl);

      document.onmousemove = (event) => {
        mousePosX = event.clientX;
        mousePosY = event.clientY;
      };

      window.onekoInterval = setInterval(frame, 100);
    }

    function setSprite(name, frame) {
      const sprite = spriteSets[name][frame % spriteSets[name].length];
      nekoEl.style.backgroundPosition = `${sprite[0] * 32}px ${sprite[1] * 32}px`;
    }

    function resetIdleAnimation() {
      idleAnimation = null;
      idleAnimationFrame = 0;
    }

    function idle() {
      idleTime += 1;

      // every ~ 20 seconds
      if (idleTime > 10 && true && idleAnimation == null) {
        let avalibleIdleAnimations = ["sleeping", "scratchSelf"];
        if (nekoPosX < 32) {
          avalibleIdleAnimations.push("scratchWallW");
        }
        if (nekoPosY < 32) {
          avalibleIdleAnimations.push("scratchWallN");
        }
        if (nekoPosX > window.innerWidth - 32) {
          avalibleIdleAnimations.push("scratchWallE");
        }
        if (nekoPosY > window.innerHeight - 32) {
          avalibleIdleAnimations.push("scratchWallS");
        }
        idleAnimation =
          avalibleIdleAnimations[
            Math.floor(Math.random() * avalibleIdleAnimations.length)
          ];
      }

      switch (idleAnimation) {
        case "sleeping":
          if (idleAnimationFrame < 8) {
            setSprite("tired", 0);
            break;
          }
          setSprite("sleeping", Math.floor(idleAnimationFrame / 4));
          if (idleAnimationFrame > 192) {
            resetIdleAnimation();
          }
          break;
        case "scratchWallN":
        case "scratchWallS":
        case "scratchWallE":
        case "scratchWallW":
        case "scratchSelf":
          setSprite(idleAnimation, idleAnimationFrame);
          if (idleAnimationFrame > 9) {
            resetIdleAnimation();
          }
          break;
        default:
          setSprite("idle", 0);
          return;
      }
      idleAnimationFrame += 1;
    }

    function frame() {
      frameCount += 1;
      const diffX = nekoPosX - mousePosX;
      const diffY = nekoPosY - mousePosY;
      const distance = Math.sqrt(diffX ** 2 + diffY ** 2);

      if (distance < nekoSpeed || distance < 48) {
        idle();
        return;
      }

      idleAnimation = null;
      idleAnimationFrame = 0;

      if (idleTime > 1) {
        setSprite("alert", 0);
        // count down after being alerted before moving
        idleTime = Math.min(idleTime, 7);
        idleTime -= 1;
        return;
      }

      direction = diffY / distance > 0.5 ? "N" : "";
      direction += diffY / distance < -0.5 ? "S" : "";
      direction += diffX / distance > 0.5 ? "W" : "";
      direction += diffX / distance < -0.5 ? "E" : "";
      setSprite(direction, frameCount);

      nekoPosX -= (diffX / distance) * nekoSpeed;
      nekoPosY -= (diffY / distance) * nekoSpeed;

      nekoPosX = Math.min(Math.max(16, nekoPosX), window.innerWidth - 16);
      nekoPosY = Math.min(Math.max(16, nekoPosY), window.innerHeight - 16);

      nekoEl.style.left = `${nekoPosX - 16}px`;
      nekoEl.style.top = `${nekoPosY - 16}px`;
    }

    create();
  })();