- Fixes#21739
With the DarkStalkers hack, SoftGPU skips the game's stretch blit and
stretches the source image to the screen itself. Libretro always presents
software rendering at 480x272, so that stretch happened at 1x and the
frontend then scaled up a blurry image.
Now libretro gets the 384x224 source as is, with the aspect the game would
have stretched it to, and switches back to the full frame when the game
stops using the stretch. GL and D3D11 read the frame from a corner of their
larger framebuffer. RetroArch's Vulkan driver samples the whole image the
core hands it, so the Vulkan presentation images are resized to the frame.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
libretro/libretro_vulkan.cpp got PPSSPP's libretro core working with
RetroArch's Vulkan integration by globally monkey-patching PPSSPP's Vulkan
loader function pointers (vkCreateInstance, vkCreateDevice,
vkCreateSwapchainKHR, vkAcquireNextImageKHR, vkQueuePresentKHR,
vkQueueSubmit, etc.) so the unmodified VulkanContext class would end up
wrapping RetroArch's already-existing VkInstance/VkDevice instead of
creating its own, and so a fake VkSwapchainKHR (a self-managed array of
images synced against RetroArch's retro_hw_render_interface_vulkan
callbacks) could stand in for the real swapchain that libretro's Vulkan
model doesn't have. Flagged in-code as "a wacky wrapper".
Replaces that with first-class support in VulkanContext for the two things
libretro actually needs:
- Adopting an externally-created instance/device instead of faking
vkCreateInstance/vkCreateDevice: VulkanContext::CreateInstanceExternal()
adopts RetroArch's VkInstance; CreateDevice() gained optional
extraDeviceExtensions/extraRequiredFeatures params so RetroArch's
requirements get merged into a real vkCreateDevice() call;
ownsInstance_/ownsDevice_ flags (the latter set via
SetDeviceExternallyOwned()) mean DestroyInstance()/DestroyDevice() skip
the real vkDestroy* calls when something else owns the object, without
needing to intercept anything. VulkanLoader gained
VulkanLoadFromGetInstanceProcAddr() for bootstrapping from a
host-supplied proc-addr getter instead of dlopen/dlsym-ing the loader
ourselves - vkGetDeviceProcAddr is resolved via the real instance handle
(not NULL), since per the Vulkan spec it's not one of the handful of
commands queryable with a NULL instance.
- A pluggable presentation backend (Common/GPU/Vulkan/VulkanPresentation.h)
for hosts with no real VK_KHR_swapchain, replacing the fake-swapchain-
handle trick. VulkanContext::GetPresentation() is null by default, so
every existing platform's real-swapchain code path is untouched;
libretro/LibretroVulkanPresentation implements this interface directly
against retro_hw_render_interface_vulkan, as real class state instead of
file-scope globals. Several pieces of state that are normally only
populated as a side effect of ReinitSurface()/InitSwapchain() - the
graphics queue/queue family index (ChooseQueue() is entangled with
real-surface presentation-support checks), the swapchain format, and
the available present modes - needed presentation-aware fallbacks since
libretro never calls that real-surface path at all.
libretro/LibretroVulkanContext.cpp now drives VulkanContext's real, public
API directly - no more hijacked function pointers, no more fake surface or
swapchain. libretro/libretro_vulkan.cpp is deleted.
Verified with a full build+run in RetroArch (not just compile-time
checks): the libretro Makefile doesn't track header dependencies
(cl.exe doesn't support -MMD/-MP, and Makefile.common never sets up an
equivalent), so a `make clean` full rebuild is required after any header
change to avoid linking stale object code from before the change - several
of the fixes above were initially masked by exactly that.
