Unable to get proper vec4 value in uniform for frag shader

[sbrkopac]

Here is an example program that shows my issue. I'm trying to add a "switch" to a uniform that is 1 or 0 and has a vec4 value associated with it. If it's 0 I want to use the vec4 as the color for the mesh rather than the texture.

I've been starting to use RenderDoc and when I look at a frame, I see the following:

Note that I'm expecting vec4(1.0f, 1.0f, 0.0, 1.0f)

When I look at the FS in RenderDoc:

I believe I'm doing everything cleanly in the VSG side. Extra eyes would be great.

Thanks!

[rolandhill]

Hi Sam, I'm wondering if you have fallen for the classic structure packing problem (I certainly have). Shader structures are packed to 16 byte boundaries, so your structure layout(binding = 1) uniform Switch { int useTexture; vec4 flatColor; } switchData; is probably getting 12 bytes extra padding between useTexture and flatColor, which isn't accounted for when you load it on the CPU side. A simple test would be to put an extra 3 x int dummy values in before flatColor, or to switch useTexture and flatColor around so that flatColor packs first (don't forget to do it in c++ code and in the shader). Worth a try. Cheers, Roland

…

On Tue, 20 Feb 2024 at 13:19, Sam Brkopac ***@***.***> wrote: Here is an example program that shows my issue <https://gist.github.com/sbrkopac/18ae8880ea7cc33e889f197a2be0490d>. I'm trying to add a "switch" to a uniform that is 1 or 0 and has a vec4 value associated with it. If it's 0 I want to use the vec4 as the color for the mesh rather than the texture. I've been starting to use RenderDoc and when I look at a frame, I see the following: image.png (view on web) <https://github.com/vsg-dev/VulkanSceneGraph/assets/1939712/c3f05793-2b30-45e2-a3dd-7c84591fb638> Note that I'm expecting vec4(1.0f, 1.0f, 0.0, 1.0f) When I look at the FS in RenderDoc: image.png (view on web) <https://github.com/vsg-dev/VulkanSceneGraph/assets/1939712/9ec309b5-6cd4-4e29-ab53-b41594ae9218> I believe I'm doing everything cleanly in the VSG side. Extra eyes would be great. Thanks! — Reply to this email directly, view it on GitHub <#1088>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAPOEQ2U4M7AOTKY3WQOL7LYUQBZTAVCNFSM6AAAAABDQK4OS6VHI2DSMVQWIX3LMV43ERDJONRXK43TNFXW4OZWGI2DEMJUHE> . You are receiving this because you are subscribed to this thread.Message ID: ***@***.***>

[sbrkopac]

Yup, that was exactly it. Thanks very much, Rolland!