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<b><a class="bz_bug_link
bz_status_NEW "
title="NEW - Shadertoy shader causing hang"
href="https://bugs.freedesktop.org/show_bug.cgi?id=111241#c3">Comment # 3</a>
on <a class="bz_bug_link
bz_status_NEW "
title="NEW - Shadertoy shader causing hang"
href="https://bugs.freedesktop.org/show_bug.cgi?id=111241">bug 111241</a>
from <span class="vcard"><a class="email" href="mailto:pierre-eric.pelloux-prayer@amd.com" title="Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>"> <span class="fn">Pierre-Eric Pelloux-Prayer</span></a>
</span></b>
<pre>Here's my understanding of the issue.
This shader uses 2 passes:
- the first pass has BufferA as input and output and does:
if (first frame)
// init bufferA content
else
// do something useful
- the 2nd pass has BufferA as input and does:
N = texelFetch(bufferA)
for(i=0; i < N; i++)
// do something
The problem here is the "// init bufferA content": it fails to initialize the
buffer content properly, leading to an infinite loop in the 2nd pass.
The exact code is:
if (iFrame==0) { O -= O; return; }
If one replaces this line with:
if (iFrame==0) { O = vec4(0.0f); return; }
The shader works fine (you can test the modified version here:
<a href="https://www.shadertoy.com/view/wtSXzw">https://www.shadertoy.com/view/wtSXzw</a> ).</pre>
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