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Replacing p with (p * vec3(1.0) leads to malformed image

Alastair_D_1
Beginner
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I attach a .zip containing shader.frag (among other files), and two .png images; good.png and bad.png.

shader.frag is taken from http://glslsandbox.com/ (some acks below for the original source) and is meant to produce an image looking like good.png.

If the expression "p" at line 27 is replaced with "(p * vec3(1.0))", the shader produces an image looking like bad.png.

As with my previous report, I believe this is due to a compiler bug, since this expression change should likely have no effect (I would expect it to be optimized away).

My platform:

- Windows 10
- Intel(R) HD Graphics 520
- Driver version 20.19.15.4326

The attached archive contains the necessary files to reproduce this problem, with instructions on how to do so in README.txt.

Acks for the original shader:

// PlayingMarble.glsl
// original code from https://www.shadertoy.com/view/MtX3Ws
// simplified edit: Robert 25.11.2015
// see also https://www.shadertoy.com/view/Mlj3zWprecision mediump float;
// modified color calculation by I.G.P.

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Michael_C_Intel2
Employee
540 Views

Hi,

Got it filed, and I will update you when we know something.

Thanks,

-Michael

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Michael_C_Intel2
Employee
540 Views

Hi Alastair,

We found the root cause and have a fix. It should be in the next driver release. 

-Michael

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Alastair_D_1
Beginner
540 Views

Great, thanks for confirming.

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