From 41e39ea6e1480fb6f3afacec093d58c94250050b Mon Sep 17 00:00:00 2001
From: luigifcruz <luigifcruz@gmail.com>
Date: Thu, 23 Dec 2021 17:04:35 -0300
Subject: [PATCH] Backends: Metal: Add Metal C++ bindings support. (#4824,
 #4746)

---
 backends/imgui_impl_metal.h  | 38 +++++++++++++++++++++++++++++++++++
 backends/imgui_impl_metal.mm | 39 +++++++++++++++++++++++++++++++++++-
 docs/CHANGELOG.txt           |  4 +++-
 3 files changed, 79 insertions(+), 2 deletions(-)

diff --git a/backends/imgui_impl_metal.h b/backends/imgui_impl_metal.h
index c0c60181..469516b4 100644
--- a/backends/imgui_impl_metal.h
+++ b/backends/imgui_impl_metal.h
@@ -12,6 +12,12 @@
 
 #include "imgui.h"      // IMGUI_IMPL_API
 
+//-----------------------------------------------------------------------------
+// ObjC API
+//-----------------------------------------------------------------------------
+
+#ifdef __OBJC__
+
 @class MTLRenderPassDescriptor;
 @protocol MTLDevice, MTLCommandBuffer, MTLRenderCommandEncoder;
 
@@ -27,3 +33,35 @@ IMGUI_IMPL_API bool ImGui_ImplMetal_CreateFontsTexture(id<MTLDevice> device);
 IMGUI_IMPL_API void ImGui_ImplMetal_DestroyFontsTexture();
 IMGUI_IMPL_API bool ImGui_ImplMetal_CreateDeviceObjects(id<MTLDevice> device);
 IMGUI_IMPL_API void ImGui_ImplMetal_DestroyDeviceObjects();
+
+#endif
+
+//-----------------------------------------------------------------------------
+// C++ API
+//-----------------------------------------------------------------------------
+
+// Enable Metal C++ binding support with '#define IMGUI_IMPL_METAL_CPP' in your imconfig.h file
+// More info about using Metal from C++: https://developer.apple.com/metal/cpp/
+
+#ifdef IMGUI_IMPL_METAL_CPP
+
+#include <Metal/Metal.hpp>
+
+#ifndef __OBJC__
+
+IMGUI_IMPL_API bool ImGui_ImplMetal_Init(MTL::Device* device);
+IMGUI_IMPL_API void ImGui_ImplMetal_Shutdown();
+IMGUI_IMPL_API void ImGui_ImplMetal_NewFrame(MTL::RenderPassDescriptor* renderPassDescriptor);
+IMGUI_IMPL_API void ImGui_ImplMetal_RenderDrawData(ImDrawData* draw_data,
+                                                   MTL::CommandBuffer* commandBuffer,
+                                                   MTL::RenderCommandEncoder* commandEncoder);
+
+// Called by Init/NewFrame/Shutdown
+IMGUI_IMPL_API bool ImGui_ImplMetal_CreateFontsTexture(MTL::Device* device);
+IMGUI_IMPL_API void ImGui_ImplMetal_DestroyFontsTexture();
+IMGUI_IMPL_API bool ImGui_ImplMetal_CreateDeviceObjects(MTL::Device* device);
+IMGUI_IMPL_API void ImGui_ImplMetal_DestroyDeviceObjects();
+
+#endif
+
+#endif
diff --git a/backends/imgui_impl_metal.mm b/backends/imgui_impl_metal.mm
index 26ddc922..1b156091 100644
--- a/backends/imgui_impl_metal.mm
+++ b/backends/imgui_impl_metal.mm
@@ -12,6 +12,7 @@
 
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
+//  2021-12-30: Metal: Added Metal C++ support. Enable with '#define IMGUI_IMPL_METAL_CPP' in your imconfig.h file.
 //  2021-08-24: Metal: Fixed a crash when clipping rect larger than framebuffer is submitted. (#4464)
 //  2021-05-19: Metal: Replaced direct access to ImDrawCmd::TextureId with a call to ImDrawCmd::GetTexID(). (will become a requirement)
 //  2021-02-18: Metal: Change blending equation to preserve alpha in output buffer.
@@ -77,7 +78,43 @@
 
 static MetalContext *g_sharedMetalContext = nil;
 
-#pragma mark - ImGui API implementation
+#ifdef IMGUI_IMPL_METAL_CPP
+
+#pragma mark - Dear ImGui Metal C++ Backend API
+
+bool ImGui_ImplMetal_Init(MTL::Device* device)
+{
+    return ImGui_ImplMetal_Init((id<MTLDevice>)(device));
+}
+
+void ImGui_ImplMetal_NewFrame(MTL::RenderPassDescriptor* renderPassDescriptor)
+{
+    ImGui_ImplMetal_NewFrame((MTLRenderPassDescriptor*)(renderPassDescriptor));
+}
+
+void ImGui_ImplMetal_RenderDrawData(ImDrawData* draw_data,
+                                    MTL::CommandBuffer* commandBuffer,
+                                    MTL::RenderCommandEncoder* commandEncoder)
+{
+    ImGui_ImplMetal_RenderDrawData(draw_data,
+                                   (id<MTLCommandBuffer>)(commandBuffer),
+                                   (id<MTLRenderCommandEncoder>)(commandEncoder));
+
+}
+
+bool ImGui_ImplMetal_CreateFontsTexture(MTL::Device* device)
+{
+    return ImGui_ImplMetal_CreateFontsTexture((id<MTLDevice>)(device));
+}
+
+bool ImGui_ImplMetal_CreateDeviceObjects(MTL::Device* device)
+{
+    return ImGui_ImplMetal_CreateDeviceObjects((id<MTLDevice>)(device));
+}
+
+#endif // #ifdef IMGUI_IMPL_METAL_CPP
+
+#pragma mark - Dear ImGui Metal Backend API
 
 bool ImGui_ImplMetal_Init(id<MTLDevice> device)
 {
diff --git a/docs/CHANGELOG.txt b/docs/CHANGELOG.txt
index 82d14664..9767f0ba 100644
--- a/docs/CHANGELOG.txt
+++ b/docs/CHANGELOG.txt
@@ -35,8 +35,10 @@ HOW TO UPDATE?
  VERSION 1.87 WIP (In Progress)
 -----------------------------------------------------------------------
 
-- Backends: OpenGL3: Fixed a buffer overflow in imgui_impl_opengl3_loader.h init, added in 1.86 (#4468, #4830) [@dymk]
+- Backends: OpenGL3: Fixed a buffer overflow in imgui_impl_opengl3_loader.h init (added in 1.86). (#4468, #4830) [@dymk]
   It would generally not have noticeable side-effect at runtime but would be detected by runtime checkers.
+- Backends: Metal: Added Apple Metal C++ API support. (#4824, #4746) [@luigifcruz]
+  Enable with '#define IMGUI_IMPL_METAL_CPP' in your imconfig.h file.
 
 
 -----------------------------------------------------------------------