boatTick copy.js

window.BoatTick = {
  tick(boat) {
    const deltaTime = 1 / 60;
    if (!boat.group) return;

    const tillerAngle = boat.tillerAngle || 0;
    const sheetLength = boat.sheetLength || 0;

    // === APPARENT WIND ANGLE (AWA) ===
    let awa = (boat.windDir - boat.headingDeg + 360) % 360;
    if (awa > 180) awa -= 360;
    const awaRad = awa * Math.PI / 180;
    const absAwa = Math.abs(awaRad);

    // === NO-GO ZONE: ±40° (no lift) ===
    const NO_GO_ZONE = 40 * Math.PI / 180; // 40° in radians
    if (absAwa < NO_GO_ZONE) {
      boat.speed = 0; // can't sail into the wind
    } else {
      const trimEfficiency = 1 - sheetLength;
      const liftCoeff = Math.sin(absAwa) * Math.sin(absAwa);
      const lift = liftCoeff * trimEfficiency;

      const windSpeedPx = boat.windSpeed * 20;
      const speedFactor = 0.9 * 0.25;
      boat.speed = lift * windSpeedPx * speedFactor;
    }

    // === TURN ===
    const turnRate = tillerAngle * boat.maxTurn;
    boat.headingDeg += turnRate * deltaTime;
    boat.headingDeg = ((boat.headingDeg % 360) + 360) % 360;

    // === MOVE ===
    const rad = boat.headingDeg * Math.PI / 180;
    const dx = Math.sin(rad) * boat.speed * deltaTime * 60;
    const dy = -Math.cos(rad) * boat.speed * deltaTime * 60;
    boat.x += dx;
    boat.y += dy;

    // === WRAP FROM TOP TO BOTTOM ===
    const screenTop = 100;
    const resetY = 750;
    if (boat.y < screenTop) {
      boat.y = resetY;
      boat.x = 400; // optional: recenter
    }

    // === RENDER ===
    boat.group.transform({
      translateX: boat.x,
      translateY: boat.y,
      rotate: boat.headingDeg,
      originX: boat.centerX,
      originY: boat.centerY
    });
  }
};