UV's animation vertex program

Unity Engine
1

Hi,

I’m experiencing weird issues related to texture sampling of animated uvs.
Basically I have a simple frame based animation for the uvs which I have done many times before
on the vertex program. Recently, I have noticed a visual issues when using this kind of shader.

Here is the animation code:

v.texcoord /= NUM_FRAMES_PER_ROW;
float2 vAnimXY = floor(_Time.yy*float2(NUM_FRAMES, NUM_FRAMES_PER_ROW)) * RAME_UV_SIZE;
v.texcoord.xy += vAnimXY;

When I move the uvs animation code from the vertex to the fragment program, the results are correct ,please advise.

Vertex animation:


Fragment animation:

I’m using Unity 2019.2.16f1

Thank you very much.

5306355--533250--Fragment.png
5306355--533250--Fragment.png1017×935 14.9 KB

5306355--533253--Vertex.png
5306355--533253--Vertex.png1113×909 50.5 KB

2

Does that happen in the editor? What precision are the UVs you are passing to frag?

3

Try this:
v.texcoord.xy += frac(vAnimXY);

I suspect it’s an issue with the UV range getting large enough you’re starting to see floating point errors in the interpolated UVs. This isn’t an issue when doing it in the fragment since the floating point error is constant.

4

Hi,

Thank you very much.
the frac command did the trick!