Vulkan: Fixed a BestPractices warning for PushConstants & vkCreateCommandPool-command-buffer-reset

[JoshBot-Debug]

I enabled vk best practice and got a warning on every frame, I fixed it and would like to have it pulled if it's right.

Here is the warning:

Validation Warning: [ UNASSIGNED-BestPractices-PushConstants ] Object 0: handle = 0x555556c8e1d0, type = VK_OBJECT_TYPE_COMMAND_BUFFER; | MessageID = 0xfd5d8e3f | vkCmdDrawIndexed():  Pipeline uses push constants with 16 bytes, but byte 0 was never set with vkCmdPushConstants.

[ocornut]

I enabled vk best practice

I cannot seem to repro this when I enabled all best practices with latest VulkanSDK.
Which OS? GPU? VulkanSDK version? imgui version?

Additionally I am failing to understand how 101f534 would relate to this, could you clarify for my understanding? Thank you

[JoshBot-Debug]

@ocornut Sorry about that, I failed to mention anything remotely helpful!

Here's my computer specs:

GPU: Intel(R) Arc(tm) A750 Graphics (DG2)
Driver Version: 25.0.7
Vulkan API Version: 1.4.305
OS: Ubuntu 24.04.3 LTS (Noble)
ImGUI Version: 1.92.6 WIP
ImGUI Version Num: 19259

Under imgui/backends/vulkan/glsl_shader.vert there are two push constants that are used, scale & translate.

layout(push_constant) uniform uPushConstant {
    vec2 uScale;
    vec2 uTranslate;
} pc;

uPushConstant uses 4 floats (16 bytes).
The original code pushed scale & translate in two separate calls, at first glance it looks perfectly fine but I got the UNASSIGNED-BestPractices-PushConstants warning. I changed it to one call, it still matches the layout in the shader and it fixed the warning on my computer, not sure why though.

Original:

float scale[2];
scale[0] = 2.0f / draw_data->DisplaySize.x;
scale[1] = 2.0f / draw_data->DisplaySize.y;
float translate[2];
translate[0] = -1.0f - draw_data->DisplayPos.x * scale[0];
translate[1] = -1.0f - draw_data->DisplayPos.y * scale[1];

vkCmdPushConstants(command_buffer, bd->PipelineLayout,
                   VK_SHADER_STAGE_VERTEX_BIT, sizeof(float) * 0,
                   sizeof(float) * 2, scale);
vkCmdPushConstants(command_buffer, bd->PipelineLayout,
                   VK_SHADER_STAGE_VERTEX_BIT, sizeof(float) * 2,
                   sizeof(float) * 2, translate);

Updated:

float constants[4];
constants[0] = 2.0f / draw_data->DisplaySize.x;
constants[1] = 2.0f / draw_data->DisplaySize.y;
constants[2] = -1.0f - draw_data->DisplayPos.x * constants[0];
constants[3] = -1.0f - draw_data->DisplayPos.y * constants[1];
vkCmdPushConstants(command_buffer, bd->PipelineLayout,
                   VK_SHADER_STAGE_VERTEX_BIT, 0, sizeof(float) * 4,
                   constants);

In regards to 101f534, I got the following warning. It's unrelated to the issue above, I didn't mean to push it...

Validation Performance Warning: [ UNASSIGNED-BestPractices-vkCreateCommandPool-command-buffer-reset ] | MessageID = 0x8728e724 | vkCreateCommandPool(): pCreateInfo->flags VK_COMMAND_POOL_CREATE_RESET_COMMAND_BUFFER_BIT is set. Consider resetting entire pool instead.

I found a comment related to it and vkResetCommandBuffer is not called so I changed it to VK_COMMAND_POOL_CREATE_TRANSIENT_BIT, because it fixed the UNASSIGNED-BestPractices-vkCreateCommandPool-command-buffer-reset warning,

The comment (in the CHANGELOG comment at the top of the file):

2024-01-03: Vulkan: Stopped command pools with VK_COMMAND_POOL_CREATE_RESET_COMMAND_BUFFER_BIT as we don't reset them.

[ocornut]

I just assumed that commit was the only one: I can't really read your PR as it modified the entire file, everything was unnecessarily reformatted/rewrapped.
It would be nice if you can rework it into clean commits and force push.

[JoshBot-Debug]

I just assumed that commit was the only one: I can't really read your PR as it modified the entire file, everything was unnecessarily reformatted/rewrapped. It would be nice if you can rework it into clean commits and force push.

Alright, will do, my vscode automatically formats everything 🔥

[JoshBot-Debug]

@ocornut I removed both previous commits and made one clean one, let me know if there's anything else.