Okay, let's set up the basic structure for the Go-Kart game.

Okay, I'll add the missing THREE imports to the relevant files.

Okay, it seems there are two issues:

1. A NaN value likely occurring during geometry calculations, possibly related to rotations derived from curve tangents, especially for the boost pads.
2. A ReferenceError indicating that the Kart class or instance is not defined when expected. This is strange given the import and instantiation order in main.js.

Let's address the potential NaN issue by correcting the rotation order for the boost pads in Track.js. We'll rotate around the Y-axis first to align with the track tangent, then rotate around the X-axis to lay it flat.

The Kart is not defined error is harder to pinpoint without a stack trace, but it might be a consequence of the first error or an issue in how GameManager accesses the kart instance. We'll ensure the code structure remains logical, passing kart correctly.

Okay, the NaN error persists, likely stemming from calculations involving the curve tangents, especially when calculating rotations. Math.atan2(0, 0) results in 0, but if the tangent vector components themselves become NaN for some reason, atan2 will also return NaN, corrupting the rotation and leading to invalid vertex positions when the object's matrix is updated.

Let's add checks in Track.js to ensure the tangent vectors are valid before using them to calculate rotations for the finish line, checkpoints, and boost pads. We'll also add more robust checks in GameManager.js before calculating bounding boxes.

Okay, let's add the pre-race sequence with camera pans, a countdown, and the start boost mechanic.

We'll introduce game states to manage the flow: PRE_RACE, COUNTDOWN, RACING, FINISHED.

1. Update index.html for Countdown UI:

Add a new element to display the countdown messages.

2. Update UIManager.js:

Add methods to show/hide the main UI and display the countdown message.

3. Update GameManager.js:

Implement the game states, camera panning, countdown logic, and boost charging check.

4. Update Kart.js:

Modify the update method to prevent movement before the race starts and add a flag for the start boost. Add startBoostCharged flag.

5. Update main.js:

Modify the animate loop to handle the different game states and trigger the camera pans and countdown updates.

Key Changes:

1. index.html: Added a #countdown div for displaying "3, 2, 1, GO!".
2. UIManager.js: Added showMainUI and showCountdownMessage methods.
3. GameManager.js:
   • Defined GameState enum.
   • Added currentState property.
   • Added logic for camera panning (panPoints, updatePreRace, skipPan). Camera passed in constructor.
   • Added logic for countdown (countdownStartTime, countdownMessages, updateCountdown).
   • Added logic for start boost check (boostChargeWindowActive, boostCharged).
   • startRace method transitions state, shows UI, applies boost, and unfreezes the kart.
   • Collision/lap logic in update now only runs if currentState === GameState.RACING.
   • endRace now sets state to FINISHED and shows a message.
   • Added setStartPosition to define pan points based on the actual kart start.
   • Dependency Injection (Simplified): Added setGameManagerDependencies to pass the main clock and skip cleanup function from main.js. This isn't ideal but avoids making them global.
4. Kart.js:
   • Starts in a frozen state (isFrozen = true).
   • reset method now also sets isFrozen = true.
   • Added freeze() and unfreeze() methods.
   • The main update method now checks isFrozen at the beginning.
   • updateCamera is called even when frozen so the camera follows during countdown.
5. main.js:
   • Imports GameState.
   • The main animate loop now uses a switch statement based on gameManager.currentState to call the appropriate update functions (updatePreRace, updateCountdown, update for racing).
   • Sets up and cleans up an event listener (skipIntro) to allow skipping the pre-race pans.
   • Calls gameManager.setStartPosition after creating the kart.
   • Calls gameManager.startPreRace() to begin the sequence.
   • Dependency Injection Call: Added setGameManagerDependencies(clock, cleanupSkipListener); after creating the necessary variables in main.js.

Now, when you run the game, it should start with camera pans (skippable with any key/click), followed by the "3, 2, 1, GO!" countdown. Holding 'W' as "2" appears should give you a boost when "GO!" is shown and the race begins.*_

You're right, those are critical bugs. It seems the state transitions and timing logic need refinement.

1. Countdown during Cutscene: The countdown logic is likely starting too early or the state isn't preventing its update correctly.
2. "GO!" Persists & No Control: This indicates the state isn't properly transitioning to RACING after the countdown, so the message isn't hidden and the kart isn't unfrozen.

Let's fix the state management and timing in GameManager.js and ensure the animate loop in main.js strictly follows the current state. We'll also simplify the dependency injection by passing the clock directly.

Got it. You want the transition to the RACING state (kart unfrozen, controls active) to happen precisely when "GO!" first appears, while still allowing the "GO!" message itself to be visible for its duration.

Let's adjust the GameManager.js logic:

1. In updateCountdown, when the message index for "GO!" is reached, call startRace immediately.
2. Modify startRace to not hide the countdown message.
3. Add a check in updateCountdown (or perhaps better, at the beginning of the RACING state update in the main loop) to hide the countdown message after the "GO!" duration has passed.

You are correct! The current implementation already handles braking and reversing using the 'S' key (or the down arrow key).

Here's the relevant section in Kart.js within the update method:

javascript // --- Input Handling --- // ... (other inputs) let brakeInput = this.inputManager.isKeyPressed('s'); // ...

    // --- Acceleration / Braking / Friction ---
    // ...
    if (accelerateInput) {
      this.currentSpeed += effectiveAcceleration * deltaTime;
    } else if (brakeInput) {
      // This handles both braking (reducing positive speed)
      // and accelerating in reverse (increasing negative speed)
      this.currentSpeed -= this.braking * deltaTime;
    } else {
      // Apply friction if no acceleration or braking input
      // ... (friction logic)
    }

    // Clamp speed (allows negative speed for reverse)
    this.currentSpeed = THREE.MathUtils.clamp(this.currentSpeed, -this.maxSpeed / 3, effectiveMaxSpeed);
    // ...

    // --- Acceleration / Braking / Friction ---
    // ...
    if (accelerateInput) {
      this.currentSpeed += effectiveAcceleration * deltaTime;
    } else if (brakeInput) {
      // This handles both braking (reducing positive speed)
      // and accelerating in reverse (increasing negative speed)
      this.currentSpeed -= this.braking * deltaTime;
    } else {
      // Apply friction if no acceleration or braking input
      // ... (friction logic)
    }

    // Clamp speed (allows negative speed for reverse)
    this.currentSpeed = THREE.MathUtils.clamp(this.currentSpeed, -this.maxSpeed / 3, effectiveMaxSpeed);
    // ...

When you press 'S':

1. If currentSpeed is positive (moving forward), subtracting this.braking * deltaTime acts as a brake.
2. If currentSpeed is zero or negative (stopped or reversing), subtracting this.braking * deltaTime makes the speed more negative, causing acceleration in reverse, up to the clamped limit (-this.maxSpeed / 3).

So, the braking and reversing functionality should already be working as expected.