VideoCommon: enhance 'CustomResourceManager' for post processing

This expands the interface of 'CustomResourceManager' to get a Material for post processing a frame buffer (currently EFB).  The flow is similar to the normal draw material but distinguishes itself by not needing a UID.  The full shader is much simpler than the draw shader and is currently put inline with the shader resource.

6 files changed, 402 insertions, 79 deletions

diff --git a/Source/Core/VideoCommon/Resources/CustomResourceManager.cpp b/Source/Core/VideoCommon/Resources/CustomResourceManager.cpp
index ffb16b055a..29e215b8ea 100644
--- a/Source/Core/VideoCommon/Resources/CustomResourceManager.cpp
+++ b/Source/Core/VideoCommon/Resources/CustomResourceManager.cpp
@@ -43,7 +43,8 @@ void CustomResourceManager::Shutdown()
 
 void CustomResourceManager::Reset()
 {
-  m_material_resources.clear();
+  m_draw_material_resources.clear();
+  m_postprocessing_material_resources.clear();
   m_shader_resources.clear();
   m_texture_data_resources.clear();
   m_texture_sampler_resources.clear();
@@ -102,11 +103,11 @@ TextureDataResource* CustomResourceManager::GetTextureDataFromAsset(
   return resource.get();
 }
 
-MaterialResource* CustomResourceManager::GetMaterialFromAsset(
+MaterialResource* CustomResourceManager::GetDrawMaterialFromAsset(
     const CustomAssetLibrary::AssetID& asset_id, const GXPipelineUid& pipeline_uid,
     std::shared_ptr<VideoCommon::CustomAssetLibrary> library)
 {
-  auto& resource = m_material_resources[asset_id][PipelineToHash(pipeline_uid)];
+  auto& resource = m_draw_material_resources[asset_id][PipelineToHash(pipeline_uid)];
   if (resource == nullptr)
   {
     resource = std::make_unique<MaterialResource>(
@@ -116,11 +117,24 @@ MaterialResource* CustomResourceManager::GetMaterialFromAsset(
   return resource.get();
 }
 
-ShaderResource*
-CustomResourceManager::GetShaderFromAsset(const CustomAssetLibrary::AssetID& asset_id,
-                                          std::size_t shader_key, const GXPipelineUid& pipeline_uid,
-                                          const std::string& preprocessor_settings,
-                                          std::shared_ptr<VideoCommon::CustomAssetLibrary> library)
+MaterialResource* CustomResourceManager::GetPostProcessingMaterialFromAsset(
+    const CustomAssetLibrary::AssetID& asset_id,
+    std::shared_ptr<VideoCommon::CustomAssetLibrary> library)
+{
+  auto& resource = m_postprocessing_material_resources[asset_id];
+  if (resource == nullptr)
+  {
+    resource =
+        std::make_unique<MaterialResource>(CreateResourceContext(asset_id, std::move(library)));
+  }
+  resource->Process();
+  return resource.get();
+}
+
+ShaderResource* CustomResourceManager::GetShaderFromAsset(
+    const CustomAssetLibrary::AssetID& asset_id, std::size_t shader_key,
+    const std::optional<GXPipelineUid>& pipeline_uid, const std::string& preprocessor_settings,
+    std::shared_ptr<VideoCommon::CustomAssetLibrary> library)
 {
   auto& resource = m_shader_resources[asset_id][shader_key];
   if (resource == nullptr)
diff --git a/Source/Core/VideoCommon/Resources/CustomResourceManager.h b/Source/Core/VideoCommon/Resources/CustomResourceManager.h
index 04eaa46942..8bd0e75019 100644
--- a/Source/Core/VideoCommon/Resources/CustomResourceManager.h
+++ b/Source/Core/VideoCommon/Resources/CustomResourceManager.h
@@ -37,14 +37,20 @@ public:
   TextureDataResource*
   GetTextureDataFromAsset(const CustomAssetLibrary::AssetID& asset_id,
                           std::shared_ptr<VideoCommon::CustomAssetLibrary> library);
-  MaterialResource* GetMaterialFromAsset(const CustomAssetLibrary::AssetID& asset_id,
-                                         const GXPipelineUid& pipeline_uid,
-                                         std::shared_ptr<VideoCommon::CustomAssetLibrary> library);
+  MaterialResource*
+  GetDrawMaterialFromAsset(const CustomAssetLibrary::AssetID& asset_id,
+                           const GXPipelineUid& pipeline_uid,
+                           std::shared_ptr<VideoCommon::CustomAssetLibrary> library);
+  MaterialResource*
+  GetPostProcessingMaterialFromAsset(const CustomAssetLibrary::AssetID& asset_id,
+                                     std::shared_ptr<VideoCommon::CustomAssetLibrary> library);
 
   ShaderResource* GetShaderFromAsset(const CustomAssetLibrary::AssetID& asset_id,
-                                     std::size_t shader_key, const GXPipelineUid& pipeline_uid,
+                                     std::size_t shader_key,
+                                     const std::optional<GXPipelineUid>& pipeline_uid,
                                      const std::string& preprocessor_settings,
                                      std::shared_ptr<VideoCommon::CustomAssetLibrary> library);
+
   TextureAndSamplerResource*
   GetTextureAndSamplerFromAsset(const CustomAssetLibrary::AssetID& asset_id,
                                 std::shared_ptr<VideoCommon::CustomAssetLibrary> library);
@@ -59,7 +65,7 @@ private:
   std::unique_ptr<AsyncShaderCompiler> m_async_shader_compiler;
 
   using PipelineIdToMaterial = std::map<std::size_t, std::unique_ptr<MaterialResource>>;
-  std::map<CustomAssetLibrary::AssetID, PipelineIdToMaterial> m_material_resources;
+  std::map<CustomAssetLibrary::AssetID, PipelineIdToMaterial> m_draw_material_resources;
 
   using ShaderKeyToShader = std::map<std::size_t, std::unique_ptr<ShaderResource>>;
   std::map<CustomAssetLibrary::AssetID, ShaderKeyToShader> m_shader_resources;
@@ -70,6 +76,9 @@ private:
   std::map<CustomAssetLibrary::AssetID, std::unique_ptr<TextureAndSamplerResource>>
       m_texture_sampler_resources;
 
+  std::map<CustomAssetLibrary::AssetID, std::unique_ptr<MaterialResource>>
+      m_postprocessing_material_resources;
+
   ShaderHostConfig m_host_config;
 
   Common::EventHook m_xfb_event;
diff --git a/Source/Core/VideoCommon/Resources/MaterialResource.cpp b/Source/Core/VideoCommon/Resources/MaterialResource.cpp
index 38486d7932..d41937d992 100644
--- a/Source/Core/VideoCommon/Resources/MaterialResource.cpp
+++ b/Source/Core/VideoCommon/Resources/MaterialResource.cpp
@@ -54,6 +54,13 @@ SamplerState CalculateSamplerAnisotropy(const SamplerState& initial_sampler)
 
 namespace VideoCommon
 {
+MaterialResource::MaterialResource(Resource::ResourceContext resource_context)
+    : Resource(std::move(resource_context))
+{
+  m_material_asset = m_resource_context.asset_cache->CreateAsset<MaterialAsset>(
+      m_resource_context.primary_asset_id, m_resource_context.asset_library, this);
+}
+
 MaterialResource::MaterialResource(Resource::ResourceContext resource_context,
                                    const GXPipelineUid& pipeline_uid)
     : Resource(std::move(resource_context)), m_uid(pipeline_uid)
@@ -61,8 +68,8 @@ MaterialResource::MaterialResource(Resource::ResourceContext resource_context,
   m_material_asset = m_resource_context.asset_cache->CreateAsset<MaterialAsset>(
       m_resource_context.primary_asset_id, m_resource_context.asset_library, this);
   m_uid_vertex_format_copy =
-      g_gfx->CreateNativeVertexFormat(m_uid.vertex_format->GetVertexDeclaration());
-  m_uid.vertex_format = m_uid_vertex_format_copy.get();
+      g_gfx->CreateNativeVertexFormat(m_uid->vertex_format->GetVertexDeclaration());
+  m_uid->vertex_format = m_uid_vertex_format_copy.get();
 }
 
 void MaterialResource::ResetData()
@@ -98,7 +105,7 @@ Resource::TaskComplete MaterialResource::CollectPrimaryData()
   }
 
   CreateTextureData(m_load_data.get());
-  SetShaderKey(m_load_data.get(), &m_uid);
+  SetShaderKey(m_load_data.get(), m_uid ? &*m_uid : nullptr);
 
   return Resource::TaskComplete::Yes;
 }
@@ -140,8 +147,18 @@ Resource::TaskComplete MaterialResource::CollectDependencyData()
 
   if (m_load_data->m_material_data->next_material_asset != "")
   {
-    m_load_data->m_next_material = m_resource_context.resource_manager->GetMaterialFromAsset(
-        m_load_data->m_material_data->next_material_asset, m_uid, m_resource_context.asset_library);
+    if (m_uid)
+    {
+      m_load_data->m_next_material = m_resource_context.resource_manager->GetDrawMaterialFromAsset(
+          m_load_data->m_material_data->next_material_asset, *m_uid,
+          m_resource_context.asset_library);
+    }
+    else
+    {
+      m_load_data->m_next_material =
+          m_resource_context.resource_manager->GetPostProcessingMaterialFromAsset(
+              m_load_data->m_material_data->next_material_asset, m_resource_context.asset_library);
+    }
     m_load_data->m_next_material->AddReference(this);
     const auto data_processed = m_load_data->m_next_material->IsDataProcessed();
     if (data_processed == TaskComplete::Error)
@@ -222,33 +239,66 @@ Resource::TaskComplete MaterialResource::ProcessData()
       config.pixel_shader = m_shader_resource_data->GetPixelShader();
       config.geometry_shader = m_shader_resource_data->GetGeometryShader();
 
-      const auto actual_uid = ApplyDriverBugs(*m_uid);
-
-      if (m_material_resource_data->m_material_data->blending_state)
-        config.blending_state = *m_material_resource_data->m_material_data->blending_state;
+      if (m_uid)
+      {
+        // Draw based pipeline
+        const auto actual_uid = ApplyDriverBugs(*m_uid);
+
+        if (m_material_resource_data->m_material_data->blending_state)
+          config.blending_state = *m_material_resource_data->m_material_data->blending_state;
+        else
+          config.blending_state = actual_uid.blending_state;
+
+        if (m_material_resource_data->m_material_data->depth_state)
+          config.depth_state = *m_material_resource_data->m_material_data->depth_state;
+        else
+          config.depth_state = actual_uid.depth_state;
+
+        config.framebuffer_state = std::move(m_frame_buffer_state);
+        config.framebuffer_state.additional_color_attachment_count = 0;
+
+        config.rasterization_state = actual_uid.rasterization_state;
+        if (m_material_resource_data->m_material_data->cull_mode)
+        {
+          config.rasterization_state.cull_mode =
+              *m_material_resource_data->m_material_data->cull_mode;
+        }
+
+        config.vertex_format = actual_uid.vertex_format;
+        config.usage = AbstractPipelineUsage::GX;
+      }
       else
-        config.blending_state = actual_uid.blending_state;
+      {
+        // Post processing based pipeline
 
-      if (m_material_resource_data->m_material_data->depth_state)
-        config.depth_state = *m_material_resource_data->m_material_data->depth_state;
-      else
-        config.depth_state = actual_uid.depth_state;
+        // Many of these properties don't make sense to replace but we expose them for draw
+        // based materials, might as well allow them to be used if the user wants
 
-      config.framebuffer_state = std::move(m_frame_buffer_state);
-      config.framebuffer_state.additional_color_attachment_count = 0;
+        if (m_material_resource_data->m_material_data->blending_state)
+          config.blending_state = *m_material_resource_data->m_material_data->blending_state;
+        else
+          config.blending_state = RenderState::GetNoBlendingBlendState();
 
-      config.rasterization_state = actual_uid.rasterization_state;
-      if (m_material_resource_data->m_material_data->cull_mode)
-      {
-        config.rasterization_state.cull_mode =
-            *m_material_resource_data->m_material_data->cull_mode;
-      }
+        if (m_material_resource_data->m_material_data->depth_state)
+          config.depth_state = *m_material_resource_data->m_material_data->depth_state;
+        else
+          config.depth_state = RenderState::GetNoDepthTestingDepthState();
 
-      config.vertex_format = actual_uid.vertex_format;
-      config.usage = AbstractPipelineUsage::GX;
+        config.framebuffer_state = RenderState::GetRGBA8FramebufferState();
 
-      m_material_resource_data->m_pipeline = g_gfx->CreatePipeline(config);
+        config.rasterization_state =
+            RenderState::GetNoCullRasterizationState(PrimitiveType::Triangles);
+        if (m_material_resource_data->m_material_data->cull_mode)
+        {
+          config.rasterization_state.cull_mode =
+              *m_material_resource_data->m_material_data->cull_mode;
+        }
 
+        config.vertex_format = nullptr;
+        config.usage = AbstractPipelineUsage::Utility;
+      }
+
+      m_material_resource_data->m_pipeline = g_gfx->CreatePipeline(config);
       if (m_material_resource_data->m_pipeline)
       {
         WriteUniforms(m_material_resource_data.get());
@@ -268,7 +318,7 @@ Resource::TaskComplete MaterialResource::ProcessData()
   if (!m_processing_load_data)
   {
     auto wi = m_resource_context.shader_compiler->CreateWorkItem<WorkItem>(
-        m_load_data, std::move(shader_data), &m_uid,
+        m_load_data, std::move(shader_data), m_uid ? &*m_uid : nullptr,
         g_framebuffer_manager->GetEFBFramebufferState());
 
     // We don't need priority, that is already handled by the resource system
@@ -360,7 +410,8 @@ void MaterialResource::SetShaderKey(Data* data, GXPipelineUid* uid)
   XXH3_INITSTATE(&shader_key_hash);
   XXH3_64bits_reset_withSeed(&shader_key_hash, static_cast<XXH64_hash_t>(1));
 
-  UpdateHashWithPipeline(*uid, &shader_key_hash);
+  if (uid)
+    UpdateHashWithPipeline(*uid, &shader_key_hash);
   XXH3_64bits_update(&shader_key_hash, data->m_preprocessor_settings.c_str(),
                      data->m_preprocessor_settings.size());
 
diff --git a/Source/Core/VideoCommon/Resources/MaterialResource.h b/Source/Core/VideoCommon/Resources/MaterialResource.h
index 4842f000ea..6f4835927f 100644
--- a/Source/Core/VideoCommon/Resources/MaterialResource.h
+++ b/Source/Core/VideoCommon/Resources/MaterialResource.h
@@ -5,6 +5,7 @@
 
 #include <atomic>
 #include <memory>
+#include <optional>
 #include <string_view>
 #include <variant>
 #include <vector>
@@ -27,6 +28,7 @@ namespace VideoCommon
 class MaterialResource final : public Resource
 {
 public:
+  explicit MaterialResource(Resource::ResourceContext resource_context);
   MaterialResource(Resource::ResourceContext resource_context, const GXPipelineUid& pipeline_uid);
 
   struct TextureLikeReference
@@ -93,7 +95,9 @@ private:
   // Note: asset cache owns the asset, we access as a reference
   MaterialAsset* m_material_asset = nullptr;
 
-  GXPipelineUid m_uid;
+  // If provided, denotes this material will be used as a custom draw material.
+  // If not provided, denotes this will be used as an efb post processing material.
+  std::optional<GXPipelineUid> m_uid;
   std::unique_ptr<NativeVertexFormat> m_uid_vertex_format_copy;
 };
 }  // namespace VideoCommon
diff --git a/Source/Core/VideoCommon/Resources/ShaderResource.cpp b/Source/Core/VideoCommon/Resources/ShaderResource.cpp
index 47600f2c6a..08aa994055 100644
--- a/Source/Core/VideoCommon/Resources/ShaderResource.cpp
+++ b/Source/Core/VideoCommon/Resources/ShaderResource.cpp
@@ -10,6 +10,7 @@
 #include "VideoCommon/AbstractGfx.h"
 #include "VideoCommon/Assets/CustomAssetCache.h"
 #include "VideoCommon/AsyncShaderCompiler.h"
+#include "VideoCommon/FramebufferShaderGen.h"
 #include "VideoCommon/GeometryShaderGen.h"
 #include "VideoCommon/PipelineUtils.h"
 #include "VideoCommon/PixelShaderGen.h"
@@ -20,20 +21,223 @@ namespace VideoCommon
 {
 namespace
 {
-std::unique_ptr<AbstractShader>
-CompileGeometryShader(const GeometryShaderUid& uid, APIType api_type, ShaderHostConfig host_config)
+// TODO: the uniform buffer is combined due to the utility path only having a single
+// set of constants, this isn't ideal (both for the end user, where it's more readable
+// to see 'custom_uniforms' before variables and from Dolphin because the
+// standard uniforms have to be packed with the custom ones
+void GeneratePostProcessUniformOutput(ShaderCode& shader_source, std::string_view block_name,
+                                      std::string_view uniforms)
+{
+  shader_source.Write("UBO_BINDING(std140, 1) uniform {} {{\n", block_name);
+  shader_source.Write("\tvec4 source_resolution;\n");
+  shader_source.Write("\tvec4 target_resolution;\n");
+  shader_source.Write("\tvec4 window_resolution;\n");
+  shader_source.Write("\tvec4 source_region;\n");
+  shader_source.Write("\tint source_layer;\n");
+  shader_source.Write("\tint source_layer_pad1;\n");
+  shader_source.Write("\tint source_layer_pad2;\n");
+  shader_source.Write("\tint source_layer_pad3;\n");
+  shader_source.Write("\tuint time;\n");
+  shader_source.Write("\tuint time_pad1;\n");
+  shader_source.Write("\tuint time_pad2;\n");
+  shader_source.Write("\tuint time_pad3;\n");
+  shader_source.Write("\tint graphics_api;\n");
+  shader_source.Write("\tint graphics_api_pad1;\n");
+  shader_source.Write("\tint graphics_api_pad2;\n");
+  shader_source.Write("\tint graphics_api_pad3;\n");
+  shader_source.Write("\tuint efb_scale;\n");
+  shader_source.Write("\tuint efb_scale_pad1;\n");
+  shader_source.Write("\tuint efb_scale_pad2;\n");
+  shader_source.Write("\tuint efb_scale_pad3;\n");
+  if (!uniforms.empty())
+  {
+    shader_source.Write("{}", uniforms);
+  }
+  shader_source.Write("}};\n");
+}
+
+// TODO: move this to a more standard post processing file
+// once post processing has been cleaned up
+void GeneratePostProcessingVertexShader(ShaderCode& shader_source,
+                                        const CustomVertexContents& custom_contents)
+{
+  // Note: if blocks are the same, they need to match for the OpenGL backend
+  GeneratePostProcessUniformOutput(shader_source, "PSBlock", custom_contents.uniforms);
+
+  // Define some defines that are shared with custom draw shaders,
+  // so that a common shader code could possibly be used in both
+  shader_source.Write("#define HAS_COLOR_0 0\n");
+  shader_source.Write("#define HAS_COLOR_1 0\n");
+  shader_source.Write("#define HAS_NORMAL 0\n");
+  shader_source.Write("#define HAS_BINORMAL 0\n");
+  shader_source.Write("#define HAS_TANGENT 0\n");
+  shader_source.Write("#define HAS_TEXTURE_COORD_0 1\n");
+  for (u32 i = 1; i < 8; i++)
+  {
+    shader_source.Write("#define HAS_TEXTURE_COORD_{} 0\n", i);
+  }
+
+  // Write the common structs, might want to consider
+  // moving these to another location?
+  shader_source.Write("struct DolphinVertexInput\n");
+  shader_source.Write("{{\n");
+  shader_source.Write("\tvec4 position;\n");
+  shader_source.Write("\tvec3 texture_coord_0;\n");
+  shader_source.Write("}};\n\n");
+
+  shader_source.Write("struct DolphinVertexOutput\n");
+  shader_source.Write("{{\n");
+  shader_source.Write("\tvec4 position;\n");
+  shader_source.Write("\tvec3 texture_coord_0;\n");
+  shader_source.Write("}};\n\n");
+
+  constexpr std::string_view emulated_vertex_definition =
+      "void dolphin_process_emulated_vertex(in DolphinVertexInput vertex_input, out "
+      "DolphinVertexOutput vertex_output)";
+  shader_source.Write("{}\n", emulated_vertex_definition);
+  shader_source.Write("{{\n");
+  shader_source.Write("\tvertex_output.position = vertex_input.position;\n");
+  shader_source.Write("\tvertex_output.texture_coord_0 = vertex_input.texture_coord_0;\n");
+  shader_source.Write("}}\n");
+
+  if (custom_contents.shader.empty())
+  {
+    shader_source.Write(
+        "void process_vertex(in DolphinVertexInput vertex_input, out DolphinVertexOutput "
+        "vertex_output)\n");
+    shader_source.Write("{{\n");
+
+    shader_source.Write("\tdolphin_process_emulated_vertex(vertex_input, vertex_output);\n");
+
+    shader_source.Write("}}\n");
+  }
+  else
+  {
+    shader_source.Write("{}\n", custom_contents.shader);
+  }
+
+  if (g_backend_info.bSupportsGeometryShaders)
+  {
+    shader_source.Write("VARYING_LOCATION(0) out VertexData {{\n");
+    shader_source.Write("\tvec3 v_tex0;\n");
+    shader_source.Write("}};\n");
+  }
+  else
+  {
+    shader_source.Write("VARYING_LOCATION(0) out vec3 v_tex0;\n");
+  }
+
+  shader_source.Write("void main()\n");
+  shader_source.Write("{{\n");
+  shader_source.Write("\tDolphinVertexInput vertex_input;\n");
+  shader_source.Write("\tvec3 vert = vec3(float((gl_VertexID << 1) & 2), "
+                      "float(gl_VertexID & 2), 0.0f);\n");
+  shader_source.Write("\tvertex_input.position = vec4(vert.xy * "
+                      "float2(2.0f, -2.0f) + float2(-1.0f, 1.0f), 0.0f, 1.0f);\n");
+  shader_source.Write("\tvertex_input.texture_coord_0 = vec3(source_region.xy + "
+                      "(source_region.zw * vert.xy), 0.0f);\n");
+  shader_source.Write("\tDolphinVertexOutput vertex_output;\n");
+  shader_source.Write("\tprocess_vertex(vertex_input, vertex_output);\n");
+  shader_source.Write("\tgl_Position = vertex_output.position;\n");
+  shader_source.Write("\tv_tex0 = vertex_output.texture_coord_0;\n");
+
+  // NDC space is flipped in Vulkan
+  if (g_backend_info.api_type == APIType::Vulkan)
+  {
+    shader_source.Write("\tgl_Position.y = -gl_Position.y;\n");
+  }
+
+  shader_source.Write("}}\n");
+}
+
+void GeneratePostProcessingPixelShader(ShaderCode& shader_source,
+                                       const CustomPixelContents& custom_contents)
+{
+  GeneratePostProcessUniformOutput(shader_source, "PSBlock", custom_contents.uniforms);
+
+  shader_source.Write("SAMPLER_BINDING(0) uniform sampler2DArray samp0;\n");
+
+  if (g_backend_info.bSupportsGeometryShaders)
+  {
+    shader_source.Write("VARYING_LOCATION(0) in VertexData {{\n");
+    shader_source.Write("\tvec3 v_tex0;\n");
+    shader_source.Write("}};\n");
+  }
+  else
+  {
+    shader_source.Write("VARYING_LOCATION(0) in float3 v_tex0;\n");
+  }
+
+  shader_source.Write("FRAGMENT_OUTPUT_LOCATION(0) out vec4 ocol0;\n");
+
+  shader_source.Write("struct DolphinFragmentInput\n");
+  shader_source.Write("{{\n");
+  for (u32 i = 0; i < 1; i++)
+  {
+    shader_source.Write("\tvec3 tex{};\n", i);
+  }
+  shader_source.Write("\n");
+
+  shader_source.Write("}};\n\n");
+
+  shader_source.Write("struct DolphinFragmentOutput\n");
+  shader_source.Write("{{\n");
+  shader_source.Write("\tvec4 main;\n");
+  shader_source.Write("}};\n\n");
+
+  constexpr std::string_view emulated_fragment_definition =
+      "void dolphin_process_emulated_fragment(in DolphinFragmentInput frag_input, out "
+      "DolphinFragmentOutput frag_output)";
+  shader_source.Write("{}\n", emulated_fragment_definition);
+  shader_source.Write("{{\n");
+  shader_source.Write("\tfrag_output.main = texture(samp0, frag_input.tex0);\n");
+  shader_source.Write("}}\n");
+
+  if (custom_contents.shader.empty())
+  {
+    shader_source.Write(
+        "void process_fragment(in DolphinFragmentInput frag_input, out DolphinFragmentOutput "
+        "frag_output)\n");
+    shader_source.Write("{{\n");
+
+    shader_source.Write("\tdolphin_process_emulated_fragment(frag_input, frag_output);\n");
+
+    shader_source.Write("}}\n");
+  }
+  else
+  {
+    shader_source.Write("{}\n", custom_contents.shader);
+  }
+
+  shader_source.Write("void main()\n");
+  shader_source.Write("{{\n");
+  shader_source.Write("\tDolphinFragmentInput frag_input;\n");
+  shader_source.Write("\tfrag_input.tex0 = v_tex0;\n");
+  shader_source.Write("\tDolphinFragmentOutput frag_output;\n");
+  shader_source.Write("\tprocess_fragment(frag_input, frag_output);\n");
+  shader_source.Write("\tocol0 = frag_output.main;\n");
+  shader_source.Write("}}\n");
+}
+
+std::unique_ptr<AbstractShader> CompileGeometryShader(GeometryShaderUid* uid, APIType api_type,
+                                                      ShaderHostConfig host_config)
 {
+  if (!uid)
+  {
+    return g_gfx->CreateShaderFromSource(
+        ShaderStage::Geometry, FramebufferShaderGen::GeneratePassthroughGeometryShader(1, 0),
+        nullptr, "Custom Post Processing Geometry Shader");
+  }
+
   const ShaderCode source_code =
-      GenerateGeometryShaderCode(api_type, host_config, uid.GetUidData());
+      GenerateGeometryShaderCode(api_type, host_config, uid->GetUidData());
   return g_gfx->CreateShaderFromSource(ShaderStage::Geometry, source_code.GetBuffer(), nullptr,
-                                       fmt::format("Geometry shader: {}", *uid.GetUidData()));
+                                       fmt::format("Geometry shader: {}", *uid->GetUidData()));
 }
 
-std::unique_ptr<AbstractShader> CompilePixelShader(const PixelShaderUid& uid,
-                                                   std::string_view preprocessor_settings,
-                                                   APIType api_type,
-                                                   const ShaderHostConfig& host_config,
-                                                   RasterSurfaceShaderData* shader_data)
+std::unique_ptr<AbstractShader>
+CompilePixelShader(PixelShaderUid* uid, std::string_view preprocessor_settings, APIType api_type,
+                   const ShaderHostConfig& host_config, RasterSurfaceShaderData* shader_data)
 {
   ShaderCode shader_code;
 
@@ -89,19 +293,25 @@ std::unique_ptr<AbstractShader> CompilePixelShader(const PixelShaderUid& uid,
   // Compile the shader
   CustomPixelContents contents{.shader = shader_code.GetBuffer(),
                                .uniforms = uniform_code.GetBuffer()};
-  const ShaderCode source_code =
-      GeneratePixelShaderCode(api_type, host_config, uid.GetUidData(), contents);
+
+  ShaderCode source_code;
+  if (uid)
+  {
+    source_code = GeneratePixelShaderCode(api_type, host_config, uid->GetUidData(), contents);
+  }
+  else
+  {
+    GeneratePostProcessingPixelShader(source_code, contents);
+  }
   ShaderIncluder* shader_includer =
       shader_data->shader_includer ? &*shader_data->shader_includer : nullptr;
   return g_gfx->CreateShaderFromSource(ShaderStage::Pixel, source_code.GetBuffer(), shader_includer,
                                        "Custom Pixel Shader");
 }
 
-std::unique_ptr<AbstractShader> CompileVertexShader(const VertexShaderUid& uid,
-                                                    std::string_view preprocessor_settings,
-                                                    APIType api_type,
-                                                    const ShaderHostConfig& host_config,
-                                                    const RasterSurfaceShaderData& shader_data)
+std::unique_ptr<AbstractShader>
+CompileVertexShader(VertexShaderUid* uid, std::string_view preprocessor_settings, APIType api_type,
+                    const ShaderHostConfig& host_config, const RasterSurfaceShaderData& shader_data)
 {
   ShaderCode shader_code;
 
@@ -157,14 +367,22 @@ std::unique_ptr<AbstractShader> CompileVertexShader(const VertexShaderUid& uid,
   // Compile the shader
   CustomVertexContents contents{.shader = shader_code.GetBuffer(),
                                 .uniforms = uniform_code.GetBuffer()};
-  const ShaderCode source_code =
-      GenerateVertexShaderCode(api_type, host_config, uid.GetUidData(), contents);
+
+  ShaderCode source_code;
+  if (uid)
+  {
+    source_code = GenerateVertexShaderCode(api_type, host_config, uid->GetUidData(), contents);
+  }
+  else
+  {
+    GeneratePostProcessingVertexShader(source_code, contents);
+  }
   return g_gfx->CreateShaderFromSource(ShaderStage::Vertex, source_code.GetBuffer(), nullptr,
                                        "Custom Vertex Shader");
 }
 }  // namespace
 ShaderResource::ShaderResource(Resource::ResourceContext resource_context,
-                               const GXPipelineUid& pipeline_uid,
+                               const std::optional<GXPipelineUid>& pipeline_uid,
                                const std::string& preprocessor_setting,
                                const ShaderHostConfig& shader_host_config)
     : Resource(std::move(resource_context)), m_shader_host_config{.bits = shader_host_config.bits},
@@ -257,24 +475,46 @@ Resource::TaskComplete ShaderResource::ProcessData()
     bool Compile() override
     {
       const ShaderHostConfig shader_host_config{.bits = m_shader_bits};
-      auto actual_uid = ApplyDriverBugs(*m_uid);
-
-      ClearUnusedPixelShaderUidBits(g_backend_info.api_type, shader_host_config,
-                                    &actual_uid.ps_uid);
-      m_resource_data->m_needs_geometry_shader = shader_host_config.backend_geometry_shaders &&
-                                                 !actual_uid.gs_uid.GetUidData()->IsPassthrough();
-
-      if (m_resource_data->m_needs_geometry_shader)
+      if (m_uid)
+      {
+        // Draw based shader
+        auto actual_uid = ApplyDriverBugs(*m_uid);
+
+        ClearUnusedPixelShaderUidBits(g_backend_info.api_type, shader_host_config,
+                                      &actual_uid.ps_uid);
+        m_resource_data->m_needs_geometry_shader = shader_host_config.backend_geometry_shaders &&
+                                                   !actual_uid.gs_uid.GetUidData()->IsPassthrough();
+
+        if (m_resource_data->m_needs_geometry_shader)
+        {
+          m_resource_data->m_geometry_shader = CompileGeometryShader(
+              &actual_uid.gs_uid, g_backend_info.api_type, shader_host_config);
+        }
+        m_resource_data->m_pixel_shader =
+            CompilePixelShader(&actual_uid.ps_uid, m_preprocessor_settings, g_backend_info.api_type,
+                               shader_host_config, m_resource_data->m_shader_data.get());
+        m_resource_data->m_vertex_shader = CompileVertexShader(
+            &actual_uid.vs_uid, m_preprocessor_settings, g_backend_info.api_type,
+            shader_host_config, *m_resource_data->m_shader_data);
+      }
+      else
       {
-        m_resource_data->m_geometry_shader =
-            CompileGeometryShader(actual_uid.gs_uid, g_backend_info.api_type, shader_host_config);
+        // Post processing based shader
+
+        m_resource_data->m_needs_geometry_shader =
+            shader_host_config.backend_geometry_shaders && shader_host_config.stereo;
+        if (m_resource_data->m_needs_geometry_shader)
+        {
+          m_resource_data->m_geometry_shader =
+              CompileGeometryShader(nullptr, g_backend_info.api_type, shader_host_config);
+        }
+        m_resource_data->m_pixel_shader =
+            CompilePixelShader(nullptr, m_preprocessor_settings, g_backend_info.api_type,
+                               shader_host_config, m_resource_data->m_shader_data.get());
+        m_resource_data->m_vertex_shader =
+            CompileVertexShader(nullptr, m_preprocessor_settings, g_backend_info.api_type,
+                                shader_host_config, *m_resource_data->m_shader_data);
       }
-      m_resource_data->m_pixel_shader =
-          CompilePixelShader(actual_uid.ps_uid, m_preprocessor_settings, g_backend_info.api_type,
-                             shader_host_config, m_resource_data->m_shader_data.get());
-      m_resource_data->m_vertex_shader =
-          CompileVertexShader(actual_uid.vs_uid, m_preprocessor_settings, g_backend_info.api_type,
-                              shader_host_config, *m_resource_data->m_shader_data);
       m_resource_data->m_processing_finished = true;
       return true;
     }
@@ -291,7 +531,7 @@ Resource::TaskComplete ShaderResource::ProcessData()
   {
     std::string_view preprocessor_settings = m_preprocessor_settings;
     auto wi = m_resource_context.shader_compiler->CreateWorkItem<WorkItem>(
-        m_load_data, &m_uid, m_shader_host_config.bits, preprocessor_settings);
+        m_load_data, m_uid ? &*m_uid : nullptr, m_shader_host_config.bits, preprocessor_settings);
 
     // We don't need priority, that is already handled by the resource system
     m_resource_context.shader_compiler->QueueWorkItem(std::move(wi), 0);
diff --git a/Source/Core/VideoCommon/Resources/ShaderResource.h b/Source/Core/VideoCommon/Resources/ShaderResource.h
index 0f91cd3714..2f35087aab 100644
--- a/Source/Core/VideoCommon/Resources/ShaderResource.h
+++ b/Source/Core/VideoCommon/Resources/ShaderResource.h
@@ -4,6 +4,7 @@
 #pragma once
 
 #include <atomic>
+#include <optional>
 
 #include "VideoCommon/Resources/Resource.h"
 
@@ -16,7 +17,8 @@ namespace VideoCommon
 class ShaderResource final : public Resource
 {
 public:
-  ShaderResource(Resource::ResourceContext resource_context, const GXPipelineUid& pipeline_uid,
+  ShaderResource(Resource::ResourceContext resource_context,
+                 const std::optional<GXPipelineUid>& pipeline_uid,
                  const std::string& preprocessor_settings,
                  const ShaderHostConfig& shader_host_config);
 
@@ -61,7 +63,10 @@ private:
   bool m_processing_load_data = false;
 
   ShaderHostConfig m_shader_host_config;
-  GXPipelineUid m_uid;
+
+  // If provided, denotes this shader will be used as a custom draw shader.
+  // If not provided, denotes this will be used as an efb post processing shader.
+  std::optional<GXPipelineUid> m_uid;
   std::string m_preprocessor_settings;
 };
 }  // namespace VideoCommon