OpenGL/Win32: enabled OpenXR support

Author: TheMostDiligent

Graphics/GraphicsEngineOpenGL/CMakeLists.txt

@@ -45,6 +45,9 @@ set(INCLUDE
     include/TextureViewGLImpl.hpp
     include/VAOCache.hpp
 )
+if(DILIGENT_USE_OPENXR)
+    list(APPEND INCLUDE include/OpenXR_GLHelpers.hpp)
+endif()
 
 set(INTERFACE
     interface/BaseInterfacesGL.h
@@ -287,6 +290,11 @@ else()
     )
 endif()
 
+if(DILIGENT_USE_OPENXR)
+    target_link_libraries(Diligent-GraphicsEngineOpenGL-static PRIVATE OpenXR::headers)
+    target_compile_definitions(Diligent-GraphicsEngineOpenGL-static PRIVATE DILIGENT_USE_OPENXR=1)
+endif()
+
 add_library(Diligent-GLAdapterSelector OBJECT "src/GLAdapterSelector.cpp")
 target_link_libraries(Diligent-GLAdapterSelector PRIVATE Diligent-BuildSettings)
 

Graphics/GraphicsEngineOpenGL/include/OpenXR_GLHelpers.hpp

@@ -0,0 +1,90 @@
+/*
+ *  Copyright 2024 Diligent Graphics LLC
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ *
+ *  In no event and under no legal theory, whether in tort (including negligence),
+ *  contract, or otherwise, unless required by applicable law (such as deliberate
+ *  and grossly negligent acts) or agreed to in writing, shall any Contributor be
+ *  liable for any damages, including any direct, indirect, special, incidental,
+ *  or consequential damages of any character arising as a result of this License or
+ *  out of the use or inability to use the software (including but not limited to damages
+ *  for loss of goodwill, work stoppage, computer failure or malfunction, or any and
+ *  all other commercial damages or losses), even if such Contributor has been advised
+ *  of the possibility of such damages.
+ */
+
+#pragma once
+
+#if GL_SUPPORTED
+
+#    define XR_USE_GRAPHICS_API_OPENGL
+#    include <openxr/openxr_platform.h>
+
+using XrGraphicsRequirementsGL                                             = XrGraphicsRequirementsOpenGLKHR;
+using PFN_xrGetGLGraphicsRequirements                                      = PFN_xrGetOpenGLGraphicsRequirementsKHR;
+static constexpr char            xrGetGLGraphicsRequirementsFunctionName[] = "xrGetOpenGLGraphicsRequirementsKHR";
+static constexpr XrStructureType XR_TYPE_GRAPHICS_REQUIREMENTS_GL          = XR_TYPE_GRAPHICS_REQUIREMENTS_OPENGL_KHR;
+
+
+#else GLES_SUPPORTED
+
+#    define XR_USE_GRAPHICS_API_OPENGL_ES
+#    include <openxr/openxr_platform.h>
+
+using XrGraphicsRequirementsGL                                             = XrGraphicsRequirementsOpenGLESKHR;
+using PFN_xrGetGLGraphicsRequirements                                      = PFN_xrGetOpenGLESGraphicsRequirementsKHR;
+static constexpr char            xrGetGLGraphicsRequirementsFunctionName[] = "xrGetOpenGLESGraphicsRequirementsKHR";
+static constexpr XrStructureType XR_TYPE_GRAPHICS_REQUIREMENTS_GL          = XR_TYPE_GRAPHICS_REQUIREMENTS_OPENGL_ES_KHR;
+
+#endif
+
+namespace Diligent
+{
+
+static Version GetOpenXRRequiredGLVersion(const OpenXRAttribs* pXR) noexcept(false)
+{
+    if (pXR == nullptr || pXR->Instance == 0)
+        return {};
+
+    if (pXR->GetInstanceProcAddr == nullptr)
+        LOG_ERROR_AND_THROW("xrGetInstanceProcAddr must not be null");
+
+    XrInstance xrInstance = XR_NULL_HANDLE;
+    static_assert(sizeof(xrInstance) == sizeof(pXR->Instance), "XrInstance size mismatch");
+    memcpy(&xrInstance, &pXR->Instance, sizeof(xrInstance));
+
+    XrSystemId xrSystemId = XR_NULL_SYSTEM_ID;
+    static_assert(sizeof(xrSystemId) == sizeof(pXR->SystemId), "XrSystemId size mismatch");
+    memcpy(&xrSystemId, &pXR->SystemId, sizeof(XrSystemId));
+
+    PFN_xrGetInstanceProcAddr       xrGetInstanceProcAddr           = reinterpret_cast<PFN_xrGetInstanceProcAddr>(pXR->GetInstanceProcAddr);
+    PFN_xrGetGLGraphicsRequirements xrGetOpenGLGraphicsRequirements = nullptr;
+    if (XR_FAILED(xrGetInstanceProcAddr(xrInstance, xrGetGLGraphicsRequirementsFunctionName, reinterpret_cast<PFN_xrVoidFunction*>(&xrGetOpenGLGraphicsRequirements))))
+    {
+        LOG_ERROR_AND_THROW("Failed to get ", xrGetGLGraphicsRequirementsFunctionName, ". Make sure that XR_KHR_opengl_enable/XR_KHR_opengl_es_enable extension is enabled.");
+    }
+
+    XrGraphicsRequirementsGL xrGraphicsRequirements{XR_TYPE_GRAPHICS_REQUIREMENTS_GL};
+    if (XR_FAILED(xrGetOpenGLGraphicsRequirements(xrInstance, xrSystemId, &xrGraphicsRequirements)))
+    {
+        LOG_ERROR_AND_THROW("Failed to get OpenGL graphics requirements");
+    }
+
+    return Version{
+        XR_VERSION_MAJOR(xrGraphicsRequirements.minApiVersionSupported),
+        XR_VERSION_MINOR(xrGraphicsRequirements.minApiVersionSupported),
+    };
+}
+
+} // namespace Diligent

Graphics/GraphicsEngineOpenGL/src/GLContextWindows.cpp

@@ -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");
@@ -32,6 +32,10 @@
 #include "GLTypeConversions.hpp"
 #include "GraphicsAccessories.hpp"
 
+#if DILIGENT_USE_OPENXR
+#    include "OpenXR_GLHelpers.hpp"
+#endif
+
 namespace Diligent
 {
 
@@ -42,6 +46,15 @@ GLContext::GLContext(const EngineGLCreateInfo& InitAttribs,
     m_Context{0},
     m_WindowHandleToDeviceContext{0}
 {
+#if DILIGENT_USE_OPENXR
+    Version OpenXRRequiredGLVersion;
+    if (InitAttribs.Window.hWnd != nullptr)
+    {
+        // Check OpenXR requirements when not attaching to an existing context
+        OpenXRRequiredGLVersion = GetOpenXRRequiredGLVersion(InitAttribs.pXRAttribs);
+    }
+#endif
+
     int MajorVersion = 0, MinorVersion = 0;
     if (InitAttribs.Window.hWnd != nullptr)
     {
@@ -202,6 +215,14 @@ GLContext::GLContext(const EngineGLCreateInfo& InitAttribs,
     APIVersion = Version{static_cast<Uint32>(MajorVersion), static_cast<Uint32>(MinorVersion)};
     VERIFY(static_cast<int>(APIVersion.Major) == MajorVersion && static_cast<int>(APIVersion.Minor) == MinorVersion,
            "Not enough bits to store version number");
+
+#if DILIGENT_USE_OPENXR
+    if (InitAttribs.Window.hWnd != nullptr && OpenXRRequiredGLVersion > APIVersion)
+    {
+        LOG_ERROR("OpenGL version ", APIVersion.Major, '.', APIVersion.Minor, " does not meet minimum required version for OpenXR: ",
+                  OpenXRRequiredGLVersion.Major, '.', OpenXRRequiredGLVersion.Minor);
+    }
+#endif
 }
 
 GLContext::~GLContext()