OpenXRUtils: implemented GetOpenXRGraphicsBindingGL on Win32

Author: TheMostDiligent

Graphics/GraphicsEngineOpenGL/include/GLContextWindows.hpp

@@ -1,5 +1,5 @@
 /*
- *  Copyright 2019-2022 Diligent Graphics LLC
+ *  Copyright 2019-2024 Diligent Graphics LLC
  *  Copyright 2015-2019 Egor Yusov
  *
  *  Licensed under the Apache License, Version 2.0 (the "License");
@@ -44,6 +44,9 @@ class GLContext
 
     NativeGLContextType GetCurrentNativeGLContext();
 
+    HGLRC GetHandle() const { return m_Context; }
+    HDC   GetWindowHandleToDeviceContext() const { return m_WindowHandleToDeviceContext; }
+
 private:
     HGLRC m_Context                     = NULL;
     HDC   m_WindowHandleToDeviceContext = NULL;

Graphics/GraphicsEngineOpenGL/include/RenderDeviceGLImpl.hpp

@@ -190,6 +190,10 @@ class RenderDeviceGLImpl : public RenderDeviceBase<EngineGLImplTraits>
                                                                                   RESOURCE_DIMENSION Dimension,
                                                                                   Uint32             SampleCount) const override final;
 
+#if PLATFORM_WIN32
+    virtual NativeGLContextAttribs DILIGENT_CALL_TYPE GetNativeGLContextAttribs() const override final;
+#endif
+
     FBOCache& GetFBOCache(GLContext::NativeGLContextType Context);
     void      OnReleaseTexture(ITexture* pTexture);
 

Graphics/GraphicsEngineOpenGL/interface/RenderDeviceGL.h

@@ -1,5 +1,5 @@
 /*
- *  Copyright 2019-2023 Diligent Graphics LLC
+ *  Copyright 2019-2024 Diligent Graphics LLC
  *  Copyright 2015-2019 Egor Yusov
  *
  *  Licensed under the Apache License, Version 2.0 (the "License");
@@ -48,6 +48,20 @@ static DILIGENT_CONSTEXPR INTERFACE_ID IID_RenderDeviceGL =
 
 // clang-format off
 
+#if PLATFORM_WIN32
+/// Native GL context attributes
+struct NativeGLContextAttribsWin32
+{
+    /// Device context handle
+	void* hDC DEFAULT_INITIALIZER(nullptr);
+
+    /// Rendering context handle
+	void* hGLRC DEFAULT_INITIALIZER(nullptr);
+};
+typedef struct NativeGLContextAttribsWin32 NativeGLContextAttribsWin32;
+typedef struct NativeGLContextAttribsWin32 NativeGLContextAttribs;
+#endif
+
 /// Exposes OpenGL-specific functionality of a render device.
 DILIGENT_BEGIN_INTERFACE(IRenderDeviceGL, IRenderDevice)
 {
@@ -113,6 +127,11 @@ DILIGENT_BEGIN_INTERFACE(IRenderDeviceGL, IRenderDevice)
                                             const TextureDesc REF TexDesc,
                                             RESOURCE_STATE        InitialState,
                                             ITexture**            ppTexture) PURE;
+
+#if PLATFORM_WIN32
+    /// Returns platform-specific GL context attributes
+    VIRTUAL NativeGLContextAttribs METHOD(GetNativeGLContextAttribs)(THIS) CONST PURE;
+#endif
 };
 DILIGENT_END_INTERFACE
 
@@ -125,6 +144,7 @@ DILIGENT_END_INTERFACE
 #    define IRenderDeviceGL_CreateTextureFromGLHandle(This, ...)CALL_IFACE_METHOD(RenderDeviceGL, CreateTextureFromGLHandle, This, __VA_ARGS__)
 #    define IRenderDeviceGL_CreateBufferFromGLHandle(This, ...) CALL_IFACE_METHOD(RenderDeviceGL, CreateBufferFromGLHandle,  This, __VA_ARGS__)
 #    define IRenderDeviceGL_CreateDummyTexture(This, ...)       CALL_IFACE_METHOD(RenderDeviceGL, CreateDummyTexture,        This, __VA_ARGS__)
+#    define IRenderDeviceGL_GetNativeGLContextAttribs(This)     CALL_IFACE_METHOD(RenderDeviceGL, GetNativeGLContextAttribs, This)
 
 // clang-format on
 

Graphics/GraphicsEngineOpenGL/src/RenderDeviceGLImpl.cpp

@@ -1732,4 +1732,14 @@ void RenderDeviceGLImpl::IdleGPU()
     glFinish();
 }
 
+#if PLATFORM_WIN32
+NativeGLContextAttribs RenderDeviceGLImpl::GetNativeGLContextAttribs() const
+{
+    NativeGLContextAttribs Attribs;
+    Attribs.hDC   = m_GLContext.GetWindowHandleToDeviceContext();
+    Attribs.hGLRC = m_GLContext.GetHandle();
+    return Attribs;
+}
+#endif
+
 } // namespace Diligent

Graphics/GraphicsTools/src/OpenXRUtilitiesGL.cpp

@@ -31,6 +31,16 @@
 
 #if GL_SUPPORTED
 
+#    if PLATFORM_WIN32
+
+#        include "WinHPreface.h"
+#        include <Windows.h>
+#        include <Unknwn.h>
+#        include "WinHPostface.h"
+
+#        define XR_USE_PLATFORM_WIN32
+#    endif
+
 #    define XR_USE_GRAPHICS_API_OPENGL
 #    include <openxr/openxr_platform.h>
 
@@ -60,7 +70,23 @@ void GetOpenXRGraphicsBindingGL(IRenderDevice*  pDevice,
                                 IDeviceContext* pContext,
                                 IDataBlob**     ppGraphicsBinding)
 {
-    UNSUPPORTED("Not yet implemented");
+#if GL_SUPPORTED && PLATFORM_WIN32
+    RefCntAutoPtr<DataBlobImpl> pDataBlob{DataBlobImpl::Create(sizeof(XrGraphicsBindingOpenGLWin32KHR))};
+
+    RefCntAutoPtr<IRenderDeviceGL> pDeviceGL{pDevice, IID_RenderDeviceGL};
+    VERIFY_EXPR(pDeviceGL != nullptr);
+    NativeGLContextAttribsWin32 GLCtxAttribs = pDeviceGL->GetNativeGLContextAttribs();
+
+    XrGraphicsBindingOpenGLWin32KHR& Binding = *reinterpret_cast<XrGraphicsBindingOpenGLWin32KHR*>(pDataBlob->GetDataPtr());
+    Binding.type                             = XR_TYPE_GRAPHICS_BINDING_D3D11_KHR;
+    Binding.next                             = nullptr;
+    Binding.hDC                              = static_cast<HDC>(GLCtxAttribs.hDC);
+    Binding.hGLRC                            = static_cast<HGLRC>(GLCtxAttribs.hGLRC);
+
+    *ppGraphicsBinding = pDataBlob.Detach();
+#else
+    UNEXPECTED("OpenXR GL bindings are not supported on this platform. The application should initialize the bindings manually.");
+#endif
 }
 
 void AllocateOpenXRSwapchainImageDataGL(Uint32      ImageCount,