How do I know if my player is on the path?

When you made your path, you defined its size; for example, using a width w.  If you’re moving your player left and right, you can keep track how far you’ve moved the player from the centreline. 

• If the player’s horizontal distance is > w/2.0f, the player is off the right side of the path
• If the player’s horizontal distance is < -w/2.0f, the player is off the left side of the path

High