How to apply OnMouseDown on sprites according to z position...

Hi Omer, you need to get rid of the OnMouseDown function altogether to use a raycasting method.

Step 1: Attach the frontmostspriteclicker script to your main camera.

Step 2: Anything with a collider that you want to be able to click on must have a script attached with a function in it called OnLeftClick. If it is one of the petals you might want something like

 function OnLeftClick(raycastHit : RaycastHit2D)
 {
 //  print("ok");
     Destroy(gameObject);
 }

Step 3: Re-writing the script to use z depth won't be too complex (afraid I don't have time to do it right now) but it would be something like, where you see this code:

 // Loop through the array of raycast hits...
                 for (var i = 0; i < hits.length; i++)
                 {
                         // Get the SpriteRenderer from each game object under the click.
                         spriteRenderer = hits[i].collider.gameObject.GetComponent(SpriteRenderer);
                
                         // Access the sortingLayerID through the SpriteRenderer and store it in the sortingLayerIDArray.
                         sortingLayerIDArray[i] = spriteRenderer.sortingLayerID;
                        
                         // Access the sortingOrder through the SpriteRenderer and store it in the sortingOrderArray.
                         sortingOrderArray[i] = spriteRenderer.sortingOrder;
                 }

Don't bother accessing the sprite renderer at all and just store the z depth in an array:

 hitDepth = hits[i].collider.transform.position;

And then where you see this code:

 // Loop through the array of sprite sorting layer IDs...
                 for (var j = 0; j < sortingLayerIDArray.length; j++)
                 {
                         // If the sortingLayerID is higher that the topSortingLayer...
                         if (sortingLayerIDArray[j] >= topSortingLayer)
                         {
                                 topSortingLayer = sortingLayerIDArray[j];
                                 indexOfTopSortingLayer = j;
                         }
                 }

Put something like:

     if (hitDepth[j] >= topSortingLayer)
                                 {
                                         topSortingLayer = hitDepth[j];
                                         hitDepthOfTopSortingLayer = j;
                                 }

Hope that helps, I wish I had more time to rewrite the code properly. Let me know how you get on, I'd love to include a link to a Z depth sorting sprite clicker on the site :)

 #pragma strict
  
 private var leftClickedObject : GameObject;
 private var rightClickedObject : GameObject;
 private var frontmostRaycastHit : RaycastHit2D;
 //private var hitDepth[]:Transform;
  
 // It's necessary to access the SpriteRenderer of a game object to be able to access its sorting layer ID
 // and sorting order ("Order in Layer" in the inspector)
 private var spriteRenderer : SpriteRenderer;
  
 function Update ()
 {
         // If the left mouse button is clicked anywhere...
         if (Input.GetMouseButtonDown(0))
         {
                 // frontmostRaycastHit stores information about the RaycastHit2D that is returned by GetFrontmostRaycastHit()
                 frontmostRaycastHit = GetFrontmostRaycastHit();
  
                 // If frontmostRaycastHit is true, i,e the user hasn't clicked on nothing, i.e GetFrontmostRaycastHit() didn't return nothing...
                 if (frontmostRaycastHit)
                 {
                         // Assigns the game object that the collider that has been clicked on to leftClickedObject.
                         leftClickedObject = frontmostRaycastHit.collider.gameObject;
                        
                         // Sends the frontmostRaycast to a function called OnLeftClick in a script attached to whatever the leftClickedObject is.
                         leftClickedObject.SendMessage("OnLeftClick", frontmostRaycastHit, SendMessageOptions.DontRequireReceiver);
                 }
         }
         // If the right mouse button is clicked anywhere...
         else if (Input.GetMouseButtonDown(1))
         {
                 // frontmostRaycastHit stores information about the RaycastHit2D that is returned by GetFrontmostRaycastHit()
                 frontmostRaycastHit = GetFrontmostRaycastHit();
  
                 // If frontmostRaycastHit is true, i,e the user hasn't clicked on nothing, i.e GetFrontmostRaycastHit() didn't return nothing...
                 if (frontmostRaycastHit)
                 {
                         // Assigns the game object that the collider that has been clicked on to rightClickedObject.
                         rightClickedObject = frontmostRaycastHit.collider.gameObject;
                        
                         // Sends the frontmostRaycast to a function called OnLeftClick in a script attached to whatever the rightClickedObject is.
                         rightClickedObject.SendMessage("OnRightClick", frontmostRaycastHit, SendMessageOptions.DontRequireReceiver);
                 }
         }
 }
  
 function GetFrontmostRaycastHit(): RaycastHit2D
 {
         // Store the point where the user has clicked as a Vector3.
         var clickPosition : Vector3 = Camera.main.ScreenToWorldPoint(Input.mousePosition);
         // Retrieve all raycast hits from the click position (to the same click position - more a dot than a ray) and store them in an array called "hits".
         var hits : RaycastHit2D[] = Physics2D.LinecastAll (clickPosition, clickPosition);
  
         // If the raycast hits something...
         if (hits.length != 0)
         {
                 // A variable that will store the frontmost sorting layer that contains an object that has been clicked on as an int.
                 var topSortingLayer : int = 0;
                 // A variable that will store the index of the top sorting layer as an int.
                 var indexOfTopSortingLayer : int;
                 var hitDepthOfTopSortingLayer: int;
                 // An array that stores the IDs of all the sorting layers that contain a sprite in the path of the linecast.
                 var sortingLayerIDArray : int[] = new int[hits.length];
                 // An array that stores the sorting orders of each sprite that has been hit by the linecast
                 var sortingOrderArray : int[] = new int[hits.length];
                 // An array that stores the sorting order number of the frontmost sprite that has been clicked.
                 var topSortingOrder : int = 0;
                 // A variable that will store the index in the sortingOrderArray where topSortingOrder is. This index used with the hits array will give us our frontmost clicked sprite.
                 var indexOfTopSortingOrder : int;
  
                 // Loop through the array of raycast hits...
                 for (var i = 0; i < hits.length; i++)
                 {
 //                        // Get the SpriteRenderer from each game object under the click.
 //                        spriteRenderer = hits[i].collider.gameObject.GetComponent(SpriteRenderer);
 //               
 //                        // Access the sortingLayerID through the SpriteRenderer and store it in the sortingLayerIDArray.
 //                        sortingLayerIDArray[i] = spriteRenderer.sortingLayerID;
 //                       
 //                        // Access the sortingOrder through the SpriteRenderer and store it in the sortingOrderArray.
 //                        sortingOrderArray[i] = spriteRenderer.sortingOrder;
                     var    hitDepth = hits[i].collider.transform.position;
                 }
                
                 // Loop through the array of sprite sorting layer IDs...
                 for (var j = 0; j < sortingLayerIDArray.length; j++)
                 {
                         // If the sortingLayerID is higher that the topSortingLayer...
 //                        if (sortingLayerIDArray[j] >= topSortingLayer)
 //                        {
 //                                topSortingLayer = sortingLayerIDArray[j];
 //                                indexOfTopSortingLayer = j;
 //                        }
                                  if (hitDepth[j] >= topSortingLayer)
                             {
                             topSortingLayer = hitDepth[j];
                             hitDepthOfTopSortingLayer = j;
                             }
                         
                 }
  
                 // Loop through the array of sprite sorting orders...
                 for (var k = 0; k < sortingOrderArray.length; k++)
                 {
                         // If the sorting order of the sprite is higher than topSortingOrder AND the sprite is on the top sorting layer...
 //                        if (sortingOrderArray[k] >= topSortingOrder && sortingLayerIDArray[k] == topSortingLayer)
 //                        {
 //                                topSortingOrder = sortingOrderArray[k];
 //                                indexOfTopSortingOrder = k;
 //                        }
 //                        else
 //                        {
 //                                // Do nothing and continue loop.
 //                        }
                          if (hitDepth[k] >= topSortingLayer)
                             {
                             topSortingLayer = hitDepth[k];
                             hitDepthOfTopSortingLayer = k;
                                         }
                                        
                          
                 // How many sprites with colliders attached are underneath the click?
                 Debug.Log("How many sprites have been clicked on: " + hits.length);
                
                 // Which is the sorting layer of the frontmost clicked sprite?
                 Debug.Log("Frontmost sorting layer ID: "+ topSortingLayer);
                
                 // Which is the order in that sorting layer of the frontmost clicked sprite?
                 Debug.Log("Frontmost order in layer: "+ topSortingOrder);
  
                 // The indexOfTopSortingOrder will also be the index of the frontmost raycast hit in the array "hits".
                 return hits[indexOfTopSortingOrder];
         }
         }
         else // If the hits array has a length of 0 then nothing has been clicked...
         {
                 Debug.Log("Nothing clicked.");
                 return;
         }
 }