Player Progress Bar in 3D space

Hello,

I am trying to make a progress bar that will show the players progress as they go through the level, except unlike a sidescrolling game, the player can be both a positive and negative distance from the objective area. I found a nice tutorial that creates an excellent progress bar for the sidescroller and changed some of the values to Vector3.

However, once you go past the objective area, the bar just disappears instead of adjusting itself to be further away.

Can anyone help? I need to compare the distances of the exact center, not just the x value.

My current code:

   #pragma strict
     //Script by Will Goldstone at Unity3dstudent.com
     
     //set GUI bar width and height in the Inspector
     var barWidth : float = 500;
     
     var barHeight : float = 25;
     
     //drag a texture as the icon to move on the progress bar
     var progIcon : Texture;
     
     //where to set the GUI element to
     private var barProgress : float;
     
     //empty objects represent the start and end of a level
     var startPoint : Transform;
     
     var endPoint : Transform;
     
     //current Player position
     var playerPos : Transform;
     
     function Update()
     {
     // get level distance by subtracting start and end
     var totalDist : float = Vector3.Distance(startPoint.position, endPoint.position);
     //get player distance from start in X axis only so slopes/ height doesn't  affect result
     var playerDist : float = Vector3.Distance(startPoint.position,playerPos.position);
     //get players progress as a percentage of the whole distance
     var playerProgress : float = playerDist / totalDist * 100;
     
     //turn the playerProgress percentage back into the scale of barWidth
     barProgress = playerProgress / 100 * barWidth; 
     }
     function OnGUI()
     {
     //create a GUI group with width of the bar and twice its height
     //in order to leave room for 'Start' and 'End' text under the bar
     GUI.BeginGroup (new Rect (10, 10, barWidth, barHeight*2)); 
     
     //draw a box as the backing for the progress bar, blank text inside
     GUI.Box(Rect (0, 0, barWidth, barHeight), "");
     
     //create a label to draw the progress icon texture, use barProgress var
     //to set its X position, 0 as the Y position and width and height of the texture used
     GUI.Label (Rect(barProgress, 0, progIcon.width, progIcon.height),progIcon);
     
     //add start and end labels
     GUI.Label(Rect(progIcon.width/2, 25, 50, barHeight), "Start"); 
     GUI.Label(Rect(barWidth-30, 25, 100,barHeight), "End"); 
     
     GUI.EndGroup();
     }