a shader that would scroll a multiline text from a texture

Hmmm....

Everything is in the title, and it's what i'd like to achieve...

A multiline text on a texture that i need to draw on a banner ( the mesh ) in a scrolling manner.
I believe i have to play with UV coordinates in the shader, but i really have no idea on how to achieve this :/

Maybe ( surely ) it has already be done but i can find nothing about this ?

Anyone got an idea ?

Thanks in advance and happy unitying

 

hm..... found the way

it has to be done in the frag part of the shader with something like that:

Code (CSharp):

1.             fixed4 frag (v2f i) : SV_Target
2.             {
3.      
4.                if(i.uv.x > 1 )
5.                {
6.                   float tmp;
7.            
8.                   tmp = i.uv.x;
9.                   i.uv.x=frac(i.uv.x);
10.                   tmp=tmp-i.uv.x;
11.                   i.uv.y +=tmp*0.5;
12.                   if(i.uv.y > 1)
13.                   {
14.                      i.uv.y=1;
15.                      i.uv.x=1;
16.                   }
17.                }
18.      
19.                 // sample the texture
20.                 fixed4 col = tex2D(_MainTex, i.uv);
21.                 // apply fog
22.                 UNITY_APPLY_FOG(i.fogCoord, col);
23.                 return col;
24.             }

for a base texture like this one:


giving this result:



The only S***ty part is the 'gray' limit generated by the non linear UV wrapping:
here:

looks like it's generated by some floating point accuracy.... ?
am not sure tho :-/

happy unitying !

EDIT: thanks to @bgolus for his explainations in this post: https://forum.unity.com/threads/how-to-modify-uv-mapping-in-shader.537993/#post-3547684

 

The color errors during wrapping is due to how GPUs calculate the mip level. Short version is the GPU is selecting a very small mip because the UVs are changing so much around those pixels. It can be fixed by removing mip maps, or by using a shader that sets the mip level.
https://forum.unity.com/threads/til...shader-getting-artifacts.535793/#post-3529864


Also, there's no reason why you couldn't just have a vertical strip of text that you pan across, unless you're looking to support old pre-Metal API iOS devices and can only use PVRTC. All other GPU texture formats don't need square textures.