[Answered] In a 2D project, how do you test to see if a sprite is at a certain Y level?

Questions & Answers
1

So I’m trying to make a basic platformer as a first project, as I have never coded before, and I’m having a little trouble. I’m currently trying to program the Jump function so that the player can not jump, the release and press Jump again (causing them to jump in mid-air); I want them to only jump once, then fall back to the ground. The problem lies in that I can’t seem to make it (basically) read “If the player is at y-level -4.5, the can jump. otherwise, wait.” I’ll include my PlayerMove script so far; I don’t know if this has already been answered before, but regardless, could someone help me figure this out?
using UnityEngine;
using System.Collections;

public class PlayerMove2 : MonoBehaviour {

	public Rigidbody2D rb;

//These lines are here in case I decide I need/want them
	//	private float pressD;
	//	private float pressA;
	//	private float pressW;
	//	private float walkRight;
	//	private float walkLeft;
	//	private float jump;
	//	private float fall;

	void Start () 
	{
		rb.GetComponent<Rigidbody2D> ();
	}

	void WalkRight()
	{
		if (Input.GetKey ("d")) {
			rb.velocity = new Vector2 (2, 0);
		} 
	}

	void StopRight()
	{
		if (Input.GetKeyUp ("d")) {
			rb.velocity = new Vector2 (0, 0);
		}
	}

	void StopLeft()
	{
		if (Input.GetKeyUp ("a")) {
			rb.velocity = new Vector2 (0,0);
		}
	}

	void WalkLeft()
	{
		if (Input.GetKey ("a")) {
			rb.velocity = new Vector2 (-2, 0);
		}
	}

	void Jump()
	{
		if (//This is where the code is supposed to go){
			if (Input.GetKeyDown ("w")) {
				rb.velocity = new Vector2 (0, 5);
			}
		}
	}

	void Update () 
	{
		WalkRight ();
		StopRight ();
		WalkLeft ();
		StopLeft ();
	}
}

PLEASE NOTE: This question is slightly outdated. While the answer I received is correct, there are better ways to test for a y-position; for that matter, there are better ways to disable infinite jumps. Please refer to “Ray cast” for more info.

2

If this Script is attached to the player then you should be able to check the position of the player by referencing its gameObject.
try this in your script :

if (gameObject.transform.position.y <= -4.5){
     Debug.Log("The Player is less than 4.5");
     // Whatever else you would like to happen
}