Resolve VVL warning on incompatible OpTypeImage vs. image view format

[asuessenbach]

Description

One possible way to resolve the VVL warnings on incompatible OpTypeImage, without the need of additional extensions.
Just needs to switch the generated image from BGRA8 to RGBA8, and overwrites the function create_render_context to enforce selection of an RGBA surface format.

Build tested on Win10 with VS2022. Run tested on Win10 with NVidia GPU.

Fixes #1423

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[SaschaWillems]

I'd prefer using shaderStorageImageRead/WriteWithoutFormat and the GL_EXT_shader_image_load_formatted GLSL extension. This is widely supported. Afaik all devices that offer HW ray tracing also support that feature (which is a Vulkan 1.0 feature). Having to specify image formats in the shader is actually a legacy OpenGL thing. I do that in my own samples too btw.

[asuessenbach]

I'd prefer using shaderStorageImageRead/WriteWithoutFormat and the GL_EXT_shader_image_load_formatted GLSL extension.

But it would require support of that extension. I don't know anything about its availability.
Besides that, is BGRA8 in any respect "better" than RGBA8?
If so, we could make the shaderStorageImageWriteWithoutFormat feature optional, and use the appropriate format depending on the support of that feature.

[SaschaWillems]

No, it only requires support for shaderStorageImageRead/WriteWithoutFormat. And those are universally supported.

[asuessenbach]

Would it require something more than just requesting that shaderStorageImageWriteWithoutFormat feature?
If I request that in request_gpu_features like so:

	if (gpu.get_features().shaderStorageImageWriteWithoutFormat)
	{
		gpu.get_mutable_requested_features().shaderStorageImageWriteWithoutFormat = VK_TRUE;
	}
	else
	{
		throw std::runtime_error(std::string("Required feature <VkPhysicalDeviceFeatures::shaderStorageImageWriteWithoutFormat> is not supported"));
	}

I still get the same VVL warning.
Would I have to do something with the actual shaders?

[asuessenbach]

... and requesting both, shaderStorageImageReadWithoutFormat and shaderStorageImageWriteWithoutFormat doesn't resolve that warning either.

[SaschaWillems]

What shader language are you using? GLSL, HLSL or Slang?

[asuessenbach]

What shader language are you using? GLSL, HLSL or Slang?

I'm using the default, which I think is GLSL.

[SaschaWillems]

You need to remove the explicit image format from the shader and (At least for GLSL) need to enable the required extension.

E.g.

#version 460
#extension GL_EXT_ray_tracing : enable
#extension GL_EXT_shader_image_load_formatted : enable

layout(binding = 0, set = 0) uniform accelerationStructureEXT topLevelAS;
layout(binding = 1, set = 0) uniform image2D image;

With this change and enabling both features, the validation error no longer shows up.

[asuessenbach]

@SaschaWillems I think, it's easier, when you craft a PR to resolve that issue using those features?

[SaschaWillems]

Sure, see #1452 :)