Layered framebuffer attachments is a feature that allows applications to
write attach layered textures to a single attachment. What layer the
fragments are written to is decided from the shader using gl_Layer.
SPIR-V's Layer is GLSL's gl_Layer. It lets the application choose from a
shader stage (vertex, tessellation or geometry) which framebuffer layer
write the output fragments to.
Abstract the current OpenGL implementation into the VideoCommon
namespace and reimplement it on top of that. Doing this avoids repeating
code and logic in the Vulkan implementation.
Instead of waiting immediately for executed commands, defer the query
until the guest CPU reads it. This way we get closer to what the guest
program is doing.
To archive this we have to build a dependency queue, because host APIs
(like OpenGL and Vulkan) use ranged queries instead of counters like
NVN.
Waiting for queries implicitly uses fences and this requires a command
being queued, otherwise the driver will lock waiting until a timeout. To
fix this when there are no commands queued, we explicitly call glFlush.
Keep track of the queued OpenGL commands that can signal a fence if
waited on. As a side effect, we avoid calls to glFlush when no commands
are queued.
Vulkan's VertexIndex and InstanceIndex don't match with hardware. This
is because Nvidia implements gl_VertexID and gl_InstanceID. The math
that relates these is:
gl_VertexIndex = gl_BaseVertex + gl_VertexID
gl_InstanceIndex = gl_InstanceIndex + gl_InstanceID
To emulate it using what Vulkan's SPIR-V offers (the *Index variants)
this commit substracts gl_Base* from gl_*Index to obtain the OpenGL and
hardware's equivalent.
Some instances were using cbuf34.offset instead of cbuf34.GetOffset().
This returned the an invalid offset. Address those instances and rename
offset to "shifted_offset" to avoid future bugs.
