Fail adding uniforms for headless rendering

[dov]

I'm writing a headless test program based on the example vsgheadless.cpp , and I'm trying to add my own uniform to the shaders, but when doing so I get Vulkan validation errors, and I don't get valid values from the uniform.

Here's what I did. I added a new uniform Foo to the shaderset by the following addition to the shader sources:

#define FOO_DESCRIPTOR_SET 2
layout(set = FOO_DESCRIPTOR_SET, binding = 9) uniform FooData
{
  int foo;
} foo;

On the C++ side I then create a shaderset and try to add the Foo uniform binding through the following pseudo code:

#define FOO_DESCRIPTOR_SET 2
struct Foo {
  int foo;
};
using FooValue = vsg::Value<Foo>;
:

vsg::ref_ptr<vsg::ShaderSet> my_create_shader_set(vsg::ref_ptr<vsg::Options> options)
{
    auto shaderSet =  vsg::ShaderSet::create(vsg::ShaderStages{vertexShader, fragmentShader});

    auto fooValue = FooValue::create();
    fooValue->value().foo = 42;
    shaderSet->addDescriptorBinding("foo", "", FOO_DESCRIPTOR_SET, 9, VK_DESCRIPTOR_TYPE_STORAGE_BUFFER, 1, VK_SHADER_STAGE_VERTEX_BIT | VK_SHADER_STAGE_FRAGMENT_BIT, fooValue);
 
    shaderSet->customDescriptorSetBindings.push_back(vsg::ViewDependentStateBinding::create(FOO_DESCRIPTOR_SET));
    return shaderSet;
}

But when running the resulting programs the uniform isn't initialized and when running with Vulkan validation turned on I get the following errors:

• Validation Error: [ VUID-VkGraphicsPipelineCreateInfo-layout-07988 ] Object 0: handle = 0x210000000021, type = VK_OBJECT_TYPE_SHADER_MODULE; Object 1: handle = 0x200000000020, type = VK_OBJECT_TYPE_PIPELINE_LAYOUT; | MessageID = 0x215f02cd | vkCreateGraphicsPipelines(): pCreateInfos[0].pStages[0] SPIR-V (VK_SHADER_STAGE_VERTEX_BIT) uses descriptor [Set 0, Binding 9, variable "foo"] (type VK_DESCRIPTOR_TYPE_INLINE_UNIFORM_BLOCK or VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER_DYNAMIC or VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER) but was not declared in the pipeline layout.
  The Vulkan spec states: If a resource variables is declared in a shader, a descriptor slot in layout must match the shader stage (https://www.khronos.org/registry/vulkan/specs/1.3-extensions/html/vkspec.ht
• VUID-vkCmdDrawIndexed-None-08114(ERROR / SPEC): msgNum: 1064294454 - Validation Error: [ VUID-vkCmdDrawIndexed-None-08114 ] Object 0: handle = 0x1e000000001e, type = VK_OBJECT_TYPE_DESCRIPTOR_SET; | MessageID = 0x3f6fd836 | vkCmdDrawIndexed(): VkDescriptorSet 0x1e000000001e[] [Set 0, Binding 9, variable "foo"] is invalid.
  The Vulkan spec states: Descriptors in each bound descriptor set, specified via vkCmdBindDescriptorSets, must be valid as described by descriptor validity if they are statically used by the VkPipeline bound to the pipeline bind point used by this command and the bound VkPipeline was not created with VK_PIPELINE_CREATE_DESCRIPTOR_BUFFER_BIT_EXT (https://www.khronos.org/registry/vulkan/specs/1.3-extensions/html/vkspec.html#VUID-vkCmdDrawIn

What did I do wrong? How do I declare the uniform in pipeline layout as reported by the validation layers?

Thanks in advance!

[AnyOldName3]

That looks like you're binding the view dependent state descriptor set (lights and shadows etc.) to your new slot instead of an instance of your new descriptor set. Get rid of the shaderSet->customDescriptorSetBindings.push_back(vsg::ViewDependentStateBinding::create(FOO_DESCRIPTOR_SET)); line, or switch it back to the regular view dependent state slot.

[dov]

It appears that I made a mistake in my original post and had given different descriptor set values on the C++ side and the shader side. But it still doesn't work, and I still don't understand whether i need customDescriptorSetBindings or not.

So my question remains, how in VSG, do you fillfill the request of the validation layer, and declare the custom DescriptorSet in the pipeline layout?

When continuing using my FOO_SLOT after my change, I still get the following validation errors:

• Validation Error: [ VUID-VkGraphicsPipelineCreateInfo-layout-07988 ] Object 0: handle = 0x210000000021, type = VK_OBJECT_TYPE_SHADER_MODULE; Object 1: handle = 0x200000000020, type = VK_OBJECT_TYPE_PIPELINE_LAYOUT; | MessageID = 0x215f02cd | vkCreateGraphicsPipelines(): pCreateInfos[0].pStages[0] SPIR-V (VK_SHADER_STAGE_VERTEX_BIT) uses descriptor [Set 2, Binding 9, variable "foo"] (type VK_DESCRIPTOR_TYPE_INLINE_UNIFORM_BLOCK or VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER_DYNAMIC or VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER) but was not declared in the pipeline layout.
  The Vulkan spec states: If a resource variables is declared in a shader, a descriptor slot in layout must match the shader stage (https://www.khronos.org/registry/vulkan/specs/1.3-extensions/html/vkspec.html#VUID-VkGraphicsPipelineCreateInfo-layout-07988)
  Objects: 2
  [0] 0x210000000021, type: 15, name: NULL
  [1] 0x200000000020, type: 17, name: NULL
  :
  VUID-vkCmdDrawIndexed-None-08114(ERROR / SPEC): msgNum: 1064294454 - Validation Error: [ VUID-vkCmdDrawIndexed-None-08114 ] Object 0: handle = 0x1e000000001e, type = VK_OBJECT_TYPE_DESCRIPTOR_SET; | MessageID = 0x3f6fd836 | vkCmdDrawIndexed(): VkDescriptorSet 0x1e000000001e[] [Set 2, Binding 9, variable "foo"] is invalid.
  The Vulkan spec states: Descriptors in each bound descriptor set, specified via vkCmdBindDescriptorSets, must be valid as described by descriptor validity if they are statically used by the VkPipeline bound to the pipeline bind point used by this command and the bound VkPipeline was not created with VK_PIPELINE_CREATE_DESCRIPTOR_BUFFER_BIT_EXT (https://www.khronos.org/registry/vulkan/specs/1.3-extensions/html/vkspec.html#VUID-vkCmdDrawIndexed-None-08114)
  Objects: 1
  [0] 0x1e000000001e, type: 23, name: NULL

[AnyOldName3]

You certainly shouldn't be using customDescriptorSetBindings in the way your code above does. You're passing it vsg::ViewDependentStateBinding, which holds the light and shadow data, which is normal, but then you're using the slot for your custom descriptor set, which means if your shader uses view-dependent state, nothing will be bound to that slot, and your custom descriptor won't be bound as you've told the shaderset you want the view dependent state in that slot. I'm just repeating my previous answer here, but hopefully rephrasing it has helped.

If you use customDescriptorSetBindings to set your new descriptor (which isn't the only way to do things - you've already passed fooValue as a default binding when adding the binding, so it shouldn't be necessary at all), then you'll need to make a new custom binding subclass instead of expecting ViewDependentStateBinding to magically work.

If your shader uses the regular VSG view-dependent state for light and shadows, then you'll still need a customDescriptorSetBindings call, but that's completely unrelated to your new descriptor set, and it needs to use the view descriptor slot, not FOO_DESCRIPTOR_SET.

Take a look at the custom shaderset example, because that covers all of this.