Vulkan: Implement Quad-Buffered stereoscopy support.

Source/Core/VideoBackends/Vulkan/PostProcessing.cpp

@@ -41,11 +41,14 @@ void VulkanPostProcessing::BlitFromTexture(const TargetRectangle& dst, const Tar
                                            const Texture2D* src_tex, int src_layer,
                                            VkRenderPass render_pass)
 {
+  // If the source layer is negative we simply copy all available layers.
+  VkShaderModule geometry_shader =
+      src_layer < 0 ? g_object_cache->GetPassthroughGeometryShader() : VK_NULL_HANDLE;
   VkShaderModule fragment_shader =
       m_fragment_shader != VK_NULL_HANDLE ? m_fragment_shader : m_default_fragment_shader;
   UtilityShaderDraw draw(g_command_buffer_mgr->GetCurrentCommandBuffer(),
                          g_object_cache->GetPipelineLayout(PIPELINE_LAYOUT_STANDARD), render_pass,
-                         g_object_cache->GetPassthroughVertexShader(), VK_NULL_HANDLE,
+                         g_object_cache->GetPassthroughVertexShader(), geometry_shader,
                          fragment_shader);
 
   // Source is always bound.

Source/Core/VideoBackends/Vulkan/Renderer.cpp

@@ -949,6 +949,10 @@ void Renderer::BlitScreen(VkRenderPass render_pass, const TargetRectangle& dst_r
     post_processor->BlitFromTexture(left_rect, src_rect, src_tex, 0, render_pass);
     post_processor->BlitFromTexture(right_rect, src_rect, src_tex, 1, render_pass);
   }
+  else if (g_ActiveConfig.iStereoMode == STEREO_QUADBUFFER)
+  {
+    post_processor->BlitFromTexture(dst_rect, src_rect, src_tex, -1, render_pass);
+  }
   else
   {
     post_processor->BlitFromTexture(dst_rect, src_rect, src_tex, 0, render_pass);
@@ -1186,6 +1190,11 @@ void Renderer::CheckForConfigChanges()
     m_swap_chain->SetVSync(g_ActiveConfig.IsVSync());
   }
 
+  // For quad-buffered stereo we need to change the layer count, so recreate the swap chain.
+  if (m_swap_chain &&
+      (g_ActiveConfig.iStereoMode == STEREO_QUADBUFFER) != m_swap_chain->IsStereoEnabled())
+    ResizeSwapChain();
+
   // Wipe sampler cache if force texture filtering or anisotropy changes.
   if (anisotropy_changed || force_texture_filtering_changed)
     ResetSamplerStates();

Source/Core/VideoBackends/Vulkan/SwapChain.cpp

@@ -320,6 +320,9 @@ bool SwapChain::CreateSwapChain()
     return false;
   }
 
+  // Select the number of image layers for Quad-Buffered stereoscopy
+  uint32_t image_layers = g_ActiveConfig.iStereoMode == STEREO_QUADBUFFER ? 2 : 1;
+
   // Store the old/current swap chain when recreating for resize
   VkSwapchainKHR old_swap_chain = m_swap_chain;
 
@@ -333,7 +336,7 @@ bool SwapChain::CreateSwapChain()
                                               m_surface_format.format,
                                               m_surface_format.colorSpace,
                                               size,
-                                              1,
+                                              image_layers,
                                               image_usage,
                                               VK_SHARING_MODE_EXCLUSIVE,
                                               0,
@@ -359,6 +362,7 @@ bool SwapChain::CreateSwapChain()
 
   m_width = size.width;
   m_height = size.height;
+  m_layers = image_layers;
   return true;
 }
 
@@ -400,7 +404,7 @@ bool SwapChain::SetupSwapChainImages()
                                                 &view,
                                                 m_width,
                                                 m_height,
-                                                1};
+                                                m_layers};
 
     res = vkCreateFramebuffer(g_vulkan_context->GetDevice(), &framebuffer_info, nullptr,
                               &image.framebuffer);

Source/Core/VideoBackends/Vulkan/SwapChain.h

@@ -32,6 +32,7 @@ public:
   VkSurfaceKHR GetSurface() const { return m_surface; }
   VkSurfaceFormatKHR GetSurfaceFormat() const { return m_surface_format; }
   bool IsVSyncEnabled() const { return m_vsync_enabled; }
+  bool IsStereoEnabled() const { return m_layers == 2; }
   VkSwapchainKHR GetSwapChain() const { return m_swap_chain; }
   VkRenderPass GetRenderPass() const { return m_render_pass; }
   u32 GetWidth() const { return m_width; }
@@ -94,6 +95,7 @@ private:
 
   u32 m_width = 0;
   u32 m_height = 0;
+  u32 m_layers = 0;
 };
 
 }  // namespace Vulkan