2D Sprite Shader texcoord problem

Hi, Recently I downloaded & modified some shader codes for 2D Sprite Outline shader - which is from this tutorial : http://nielson.io/2016/04/2d-sprite-outlines-in-unity/
(In Short, shader from this tutorial treats a pixel as an outline pixel when neighboring pixel is transparent.)


I added some codes for this shader, because I trimmed every transparent pixels around my sprite resources, and for that original shader doesn't work properly :



...Like this.

So after I modified frag() a bit :

Code (csharp):

1.  
2. fixed4 frag(v2f IN) : SV_Target
3. {
4. fixed4 c = SampleSpriteTexture(IN.texcoord) * IN.color;
5.  
6. // If outline is enabled and there is a pixel, try to draw an outline.
7. if (_Outline > 0 && c.a != 0) {
8. float totalAlpha = 1.0;
9.  
10. //Color pixels when It's on the sprite texture's edge
11. if (IN.texcoord.x < _MainTex_TexelSize.x || IN.texcoord.y < _MainTex_TexelSize.y ||
12. IN.texcoord.x > 1 - _MainTex_TexelSize.x || IN.texcoord.y > 1 - _MainTex_TexelSize.y)
13. {
14. totalAlpha = 0;
15. }
16. else
17. {
18. [unroll(16)]
19. for (int i = 1; i < _OutlineSize + 1; i++) {
20. fixed4 pixelUp = tex2D(_MainTex, IN.texcoord + fixed2(0, i * _MainTex_TexelSize.y));
21. fixed4 pixelDown = tex2D(_MainTex, IN.texcoord - fixed2(0, i * _MainTex_TexelSize.y));
22. fixed4 pixelRight = tex2D(_MainTex, IN.texcoord + fixed2(i * _MainTex_TexelSize.x, 0));
23. fixed4 pixelLeft = tex2D(_MainTex, IN.texcoord - fixed2(i * _MainTex_TexelSize.x, 0));
24.  
25. totalAlpha = totalAlpha * pixelUp.a * pixelDown.a * pixelRight.a * pixelLeft.a;
26. }
27. }
28.  
29. if (totalAlpha == 0) {
30. c.rgba = fixed4(1, 1, 1, 1) * _OutlineColor;
31. }
32. }
33.  
34. c.rgb *= c.a;
35.  
36. return c;
37. }
38.  

...In the Editor, It looks OK :





But, when I hit the play button :



The outline doesn't work properly again.

What am I doing wrong here? I'm almost new to shader coding, so any help will be greatly appreciated.

(*And I didn't pack sprites manually, I just leave packing to Unity Built-In sprite packer.)

 

OK, so I assume I got the reason of this bug.

In Editor's Scene view, it seems like unity uses the original sprite file, which is not packed yet, so I can just detect sprite's edge with value 0 and 1.

But, In play mode, I guess Unity uses built-in packed sprite sheet, and for that, 0 or 1 texcoord value is now not actually the edge of my sprite, it's edge of sprite sheet.

So what I'm curious of now is, How can I get current rendering sprite's texcoord uv & size in the sprite sheet?

If i can get those, I can check if it's real 'edge' of current drawing sprite...

 

http://forum.unity3d.com/threads/relative-texcoord-when-using-sprite-atlas.400450/

Well, I just needed to pass 'rect' param to shader, That's all. But, It came with another bug - but I guess it's not related to this topic so I'll skip that in this thread.