[Solved] Compute shader on Android not working

Unity Engine
1

I’ve spent the last couple days trying to figure out why my compute shader isn’t working on Android. I’ve narrowed it down to the tex2dlod call always returning 0. Here’s a minimal example:

#pragma kernel NotWorking

RWTexture2D<float4> result;

float tex_width;
float tex_height;
sampler2D input;

[numthreads(8,8,1)]
void NotWorking (uint3 id : SV_DispatchThreadID) {
    float2 uv = float2(id.x / tex_width, id.y / tex_height);
    float4 sample = tex2Dlod(input, float4(uv.x, uv.y, 0, 0));
    result[id.xy] = sample;
}

On desktop, the output is the result texture being a copy of the input texture. As soon as I build/deploy to Android, result is just a blank (black) texture. I know the compute shader is getting executed because if I remove the tex2Dlod and replace it with a constant, I get the expected result on both platforms. EDIT: Turns out tex2Dlod wasn’t to blame. I had replaced it with float4(1,1,1,1) and that was working but other values were not. Solution below.

What am I doing wrong?!

2

Hi!
Can you please file a bug report?
Thanks!

3

@aleksandrk filed report 1214413. Thanks!

4

I spent a long time playing with all the variables I could. In the end, the one that made the shader start working was to change the format on the RenderTexture that I was using to write result into:

renderTexture.format = RenderTextureFormat.RFloat;

The default RenderTextureFormat doesn’t work on Android (gives error RENDERTEXTURE.CREATE FAILED: FORMAT UNSUPPORTED FOR RANDOM WRITES - RGBA4 UNORM (7)). I had originally tried replacing it with RenderTextureFormat.ARGB32 since that’s the most common one. Turns out that doesn’t work either. Maybe it needs a different declaration in the compute shader? I don’t know - it all worked in the editor…

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