Enable GL_EXT_texture_shadow_lod if available. If this extension is not available, such as on Intel/AMD proprietary drivers, use textureGrad as a workaround.
Variables that are marked as const cannot have the move constructor
invoked when returning from a function (the move constructor requires a
non-const variable so it can "steal" the resources from it.
Check() can throw an exception if the Vulkan result isn't successful.
We remove the check so that std::terminate isn't outright called and
allows for better debugging (should it ever actually fail).
Renames some variables to prevent ones in inner scopes from shadowing
outer-scoped variables.
The Copy* functions have no shadowing, but we rename them anyways to
remain consistent with the other functions.
We can reduce the capture scope so that it's not possible for both "reg"
variables to clash with one another.
While we're at it, we can prevent unnecessary copies while we're at it.
maxwell_to_vk: Reorder filtering modes to start with None, then Nearest, then Linear.
maxwell_to_vk: Logs filter modes under UNREACHABLE_MSG instead of UNIMPLEMENTED_MSG, since any unknown filter modes are invalid and not unimplemented.
maxwell_to_vk: Return VK_SAMPLER_MIPMAP_MODE_NEAREST instead of VK_SAMPLER_MIPMAP_MODE_LINEAR when mipmap_filter is None with the description from the VkSamplerCreateInfo(3) man page.
maxwell_to_gl: Log unimplemented features under UNIMPLEMENTED_MSG instead of LOG_ERROR to bring into parity with maxwell_to_vk
maxwell_to_gl: Deduplicate logging in VertexType(), merging them into one.
maxwell_to_gl: Return GL_NEAREST instead of GL_LINEAR if an unknown texture filter mode is encountered.
maxwell_to_gl: Log the mipmap filter mode if an unknown value is passed in.
maxwell_to_gl: Reorder filtering modes to start with None, then Nearest, then Linear.
Due to the limitation of GL_MAX_IMAGE_UNITS being low (8) on Intel's and Nvidia's proprietary drivers, we have to reserve an appropriate amount of image bindings for each of the stages. So far games have been observed to use 4 image bindings on the fragment stage (Kirby Star Allies) and 1 on the vertex stage (TWD series).
No games thus far in my limited testing used more than 4 images concurrently and across all currently active programs.
This fixes shader compilation errors on Kirby Star Allies on OpenGL (GLSL/GLASM)
All registers are now callee-save registers.
RBX and RBP selected for STATE and RESULT because these are most commonly accessed; this is to avoid the REX prefix.
RBP not used for STATE because there are some SIB restrictions, RBX emits smaller code.
