MiniDevSchool
Crazy Tractor's Seagull AI

Lesson 3: Seagull Rotation Towards Waypoints 🔄

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Rotation is crucial for ensuring that the seagulls follow their waypoints smoothly. Let’s see how we can rotate them based on their position relative to the waypoint or the player 👀.

private void RotateTowardsWaypoint()
{
    if (activeStats.isChasingPlayer && GameManager.s_player != null)
    {
        Transform activePlayerRef = GameManager.s_player.transform;

        // Increase turn speed based on distance to player 📏
        acceleratedRotation = Vector3.Distance(transform.position, activePlayerRef.position) / 1.2f;

        // Get the direction to the player
        Vector2 direction = (Vector2)activePlayerRef.position - rb.position;
        direction.Normalize();

        // Rotate towards the player based on cross product of direction and up vector 🔄
        float rotatAmount = Vector3.Cross(direction, transform.up).z;
        rb.angularVelocity = -rotatAmount * ((activeStats.rotateSpeed + acceleratedRotation) * fleeingRotatingSpeed);
    }
    else if (!activeStats.isChasingPlayer && currentWaypoint != null)
    {
        acceleratedRotation = 0;
        Vector2 direction = (Vector2)currentWaypoint.ReturnActiveWaypointTransform().position - rb.position;
        direction.Normalize();
        float rotatAmount = Vector3.Cross(direction, transform.up).z;
        rb.angularVelocity = -rotatAmount * (activeStats.rotateSpeed * fleeingRotatingSpeed);
    }
}

What the Code Does:

  • acceleratedRotation: This variable is used to increase the rotation speed based on the distance to the player. The further the player, the faster the seagull rotates.

  • Vector3.Cross(direction, transform.up).z:

    • The cross product calculates the perpendicular vector to the two input vectors (direction and up vector).

    • Why the cross product? The result tells us the direction (clockwise or counterclockwise) in which the seagull needs to rotate in order to align itself with the target. It’s essential for smooth, natural rotation. The .z component is taken since we’re working in 2D and only need the rotational value around the Z-axis.

  • rb.angularVelocity: This applies the rotational speed to the Rigidbody2D based on the calculated rotation amount.

Key Concept:

The cross product gives us the direction in which to rotate (clockwise or counterclockwise). By adjusting the angularVelocity, we can rotate the seagull smoothly towards the waypoint or player. 🔄