The magical term to know about (because the GLSL compiler or the
validation layers sure as hell don't) is:
"dynamically uniform expression"
because if you don't have that when indexing a texture or buffer array,
you need to add nonuniformEXT() around the index variable.
Fixes the close icon on AMD having glitches of the previous icon visible
in some pixels.
This reverts most of commit f420c143e0
again because it turns out GPUs like combined images and samplers.
But: The one thing we don't revert is allowing the C code to select any
combination of sampler and image:
gsk_vulkan_render_get_image_descriptor() now takes a 2nd argument
specifying the sampler.
This allows the same flexibility as before, we just combine things
early.
This change was inspired by
https://developer.nvidia.com/blog/vulkan-dos-donts/
It turns out variable length is only supported for the last binding in
a set, not for every binding.
So we need to create one set for each of our arrays.
[ VUID-VkDescriptorSetLayoutBindingFlagsCreateInfo-pBindingFlags-03004 ] Object 0: handle = 0x33a9f10, type = VK_OBJECT_TYPE_DEVICE; | MessageID = 0xd3f353a | vkCreateDescriptorSetLayout(): pBindings[0] has VK_DESCRIPTOR_BINDING_VARIABLE_DESCRIPTOR_COUNT_BIT but 0 is the largest value of all the bindings. The Vulkan spec states: If an element of pBindingFlags includes VK_DESCRIPTOR_BINDING_VARIABLE_DESCRIPTOR_COUNT_BIT, then all other elements of VkDescriptorSetLayoutCreateInfo::pBindings must have a smaller value of binding (https://www.khronos.org/registry/vulkan/specs/1.3-extensions/html/vkspec.html#VUID-VkDescriptorSetLayoutBindingFlagsCreateInfo-pBindingFlags-03004)
The idea here is that we can do more complex combinations and use that
to support texture-scale nodes or use fancy texture formats (suc as
YUV).
I'm not sure this is actually necessary, but for now it gives more
flexibility.
Instead of having a descriptor set per operation, we just have one
descriptor set and bind all our images into it.
Then the shaders get to use an index into the large texture array
instead.
Getting this to work - because it's a Vulkan extension that needs to be
manually enabled, even though it's officially part of Vulkan 1.2 - is
insane.
