GLSL 4.2 - Syntax error: "layout" parse error

Question

So, I recently found an interesting shader and tried to compile it.

But, the GLSL compiler threw the following error:

ERROR: 0:50: error(#132) Syntax error: "layout" parse error

@ (Fragment shader)

#version 420

...

uint ImageAtomic_Average_RGBA8(layout (r32ui) volatile uimage3D Img, ivec3 Coords, vec4 NewVal)
{ ... }

Details:

Card: AMD Radeon HD 7870 (It supports OpenGL 4.20)
I tried both the 4.2 driver and the 4.3 beta driver.

@bwroga The original code can be found here. I slightly modified the style though (It shouldn't affect anything) — Andreas Goulas
– Andreas Goulas, Commented Sep 29, 2013 at 17:19

thokra · Accepted Answer · 2013-09-30 08:36:07Z

1

A layout qualifier cannot be part of the function's signature. Section 6.1.1 of the GLSL 4.40 Specification defines the following grammar for a function prototype:

function-prototype :
precision-qualifier type function-name(*parameter-qualifiers* precision-qualifier type name array-specifier, ... )

Now, a parameter-qualifier can be one of

const
in
out
inout
precise
memory qualifier (volatile, ...)
precision qualifier(lowp, ...)

Consistently, section 4.10 explicitly states:

Layout qualifiers cannot be used on formal function parameters [..]

If you drop the layout qualifier, you should be fine. If not, it's a driver bug.

answered Sep 30, 2013 at 8:36

thokra

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4 Comments

Andreas Goulas Over a year ago

Oh wow, that fixed the error. However, when I try to pass an image variable to that function (e.g. ImageAtomic_Average_RGBA8(VoxelFragTex_Normal, ivec3(BaseVoxel), Normal); - Declaration: layout (r32ui) uniform volatile uimage3D VoxelFragTex_Normal;) the compiler throws this error: error(#373) Invalid usage of image qualifier. Is that related?

thokra Over a year ago

Does it generate the error at the line where the function is called? Or at the image declaration? Or somewhere else?

thokra Over a year ago

@structinf: Also, is the GitHub version your current version?

Andreas Goulas Over a year ago

With the exception of some style modifications, yes.

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