Bug 107864

Summary:	Specific Shadertoy demo renders garbage in empty parts of target surface
Product:	Mesa	Reporter:	Christopher Snowhill <kode54>
Component:	Drivers/Gallium/radeonsi	Assignee:	Default DRI bug account <dri-devel>
Status:	RESOLVED MOVED	QA Contact:	Default DRI bug account <dri-devel>
Severity:	normal
Priority:	medium
Version:	git
Hardware:	x86-64 (AMD64)
OS:	Linux (All)
Whiteboard:
i915 platform:		i915 features:

Description Christopher Snowhill 2018-09-08 02:16:38 UTC

The following Shadertoy demo:

https://www.shadertoy.com/view/Xt3cWS

renders garbage in the top and bottom strips of the target surface, which appears to be uninitialized VRAM being copied to the display surface.

It does not appear to matter which WebGL capable browser I use to run the demo, they all replicate the issue on my RX480.

I cannot get apitrace to run on Firefox without that particular page crashing on load, and I cannot get RenderDoc to attach to the tab's process and actually capture anything.

Comment 1 Ilia Mirkin 2018-09-08 03:46:08 UTC

Adding

 else {
        fragColor = vec4(0);   
 }

at the bottom of mainImage appears to "fix" it. fragColor is otherwise ending up with random values (effectively whatever happened to be in the registers, probably left over from the division check).

I don't think this is a bug in mesa.

Comment 2 GitLab Migration User 2019-09-25 18:09:46 UTC

-- GitLab Migration Automatic Message --

This bug has been migrated to freedesktop.org's GitLab instance and has been closed from further activity.

You can subscribe and participate further through the new bug through this link to our GitLab instance: https://gitlab.freedesktop.org/mesa/mesa/issues/1327.

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