Vulkan: Implement post-processing backend

No new features, just parity with OpenGL.

Source/Core/VideoBackends/Vulkan/PostProcessing.h

@@ -0,0 +1,45 @@
+// Copyright 2017 Dolphin Emulator Project
+// Licensed under GPLv2+
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <string>
+
+#include "VideoBackends/Vulkan/VulkanContext.h"
+
+#include "VideoCommon/PostProcessing.h"
+#include "VideoCommon/VideoCommon.h"
+
+namespace Vulkan
+{
+class Texture2D;
+
+class VulkanPostProcessing : public PostProcessingShaderImplementation
+{
+public:
+  VulkanPostProcessing() = default;
+  ~VulkanPostProcessing();
+
+  bool Initialize(const Texture2D* font_texture);
+
+  void BlitFromTexture(const TargetRectangle& dst, const TargetRectangle& src,
+                       const Texture2D* src_tex, int src_layer, VkRenderPass render_pass);
+
+  void UpdateConfig();
+
+private:
+  size_t CalculateUniformsSize() const;
+  void FillUniformBuffer(u8* buf, const TargetRectangle& src, const Texture2D* src_tex,
+                         int src_layer);
+
+  bool CompileDefaultShader();
+  bool RecompileShader();
+  std::string GetGLSLUniformBlock() const;
+
+  const Texture2D* m_font_texture = nullptr;
+  VkShaderModule m_fragment_shader = VK_NULL_HANDLE;
+  VkShaderModule m_default_fragment_shader = VK_NULL_HANDLE;
+};
+
+}  // namespace