Raycast hit position on sprite

[kittikun]

Hi,

I currently need to find which sprite was hit when for example I have two sprites on top of each other and the top one had a transparent empty area.

I want to point out that this post is not working in my case
http://www.tasharen.com/forum/index.php?topic=7824.0

Probably because my sprites are positionned in the world 3D. Here is my current setup:

UIRoot (3D) fixed size, 640

I am currently using the current code to achieve hit detection

1.         void Update()
2.         {
3.                 if (!Input.GetMouseButton(0))
4.                         return;
5.                
6.                 RaycastHit hit;
7.                 if (!Physics.Raycast(UICamera.mainCamera.camera.ScreenPointToRay(Input.mousePosition), out hit))
8.                         return;
9.                
10.                 UISprite sprite = hit.transform.GetComponent<UISprite>();
11.                 Vector3 localHit = hit.transform.InverseTransformPoint(hit.point);
12.  
13.  
14.                 Debug.Log(string.Format("World {0}", hit.point));
15.                 Debug.Log(string.Format("Local {0}", localHit));
16.  
17.  
18.                 if (sprite == null)
19.                         return;
20.                
21.                 Texture2D tex = sprite.mainTexture as Texture2D;
22.                 UISpriteData data = sprite.atlas.GetSprite(sprite.spriteName);
23.  
24.                 Debug.Log(string.Format("data {0} {1} {2} {3}", data.x, data.y, data.width, data.height));
25.                 Bounds bounds = sprite.CalculateBounds();
26.                 Debug.Log(string.Format("Bounds min {0}", bounds.min));
27.                 Debug.Log(string.Format("Bounds size {0}", bounds.size));
28.  
29.                 Vector2 hitLocalUV = Vector2.zero;
30.  
31.                 // normalize
32.                 if (bounds.size.x > 0)
33.                         hitLocalUV.x = (localHit.x - bounds.min.x) / (bounds.size.x);
34.  
35.                 if (bounds.size.y > 0)
36.                         hitLocalUV.y = (localHit.y - bounds.min.y) / (bounds.size.y);
37.  
38.                 Debug.Log(string.Format("hitLocalUV {0}", hitLocalUV));
39.  
40.                 Texture altasTex = sprite.atlas.texture;
41.  
42.                 // use scale to to (a.x * b.x) + (a.y * b.y)...
43.                 Vector2 hitLocalPixel = hitLocalUV;
44.                 hitLocalPixel.Scale(new Vector2(data.width, data.height));
45.                 Debug.Log(string.Format("hitLocalPixel {0}", hitLocalPixel));
46.  
47.                 Vector2 hitAtlasPixel = hitLocalPixel + new Vector2(data.x, data.y);
48.                 Debug.Log(string.Format("hitAtlasPixel {0}", hitAtlasPixel));
49.  
50.                 Color hitPixel = tex.GetPixel(Mathf.RoundToInt(hitAtlasPixel.x), Mathf.RoundToInt(hitAtlasPixel.y));
51.  
52.  
53.                 Debug.Log(string.Format("hitPixel {0}", hitPixel));
54.         }
55.  

if I click on a point that should be (348, 1200) on the atlas, I get (348, 1020) for hitAtlasPixel
There only seems to be discrepancy on Y so I was wondering if fixed size could have something to do about it but

root.pixelSizeAdjustment = 1.319588 so the ratio doesn't seem to match my problem

I feel like I am so close of it but i cannot figure it out!

It would be great if you had some tips to give

Thanks you

[ArenMook]

Mouse position and screen space are inverted, aren't they? You need to flip the mouse Y (Screen.height - y).

[kittikun]

That doesn't seem to be it, could it be that UISpriteData (0,0) is top-left ?

[kittikun]

Looks like it is, so If I change

1.  Vector2 hitAtlasPixel = hitLocalPixel + new Vector2(data.x, data.y);

to

1.                 Vector2 hitAtlasPixel = new Vector2(hitLocalPixel.x, sprite.atlas.texture.height - data.y - data.height + hitLocalPixel.y);
2.  

Everything is working fine!