OpenXRUtilities.h

/*
 *  Copyright 2024-2025 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

/// \file
/// OpenXR utilities

#include "../../GraphicsEngine/interface/RenderDevice.h"
#include "../../GraphicsEngine/interface/DeviceContext.h"
#include "../../../Primitives/interface/DataBlob.h"

#include <openxr/openxr.h>

DILIGENT_BEGIN_NAMESPACE(Diligent)

#include "../../../Primitives/interface/DefineRefMacro.h"

/// Prepares OpenXR graphics binding for the specified device and context.

/// \param [in]  pDevice           - Pointer to the render device.
/// \param [in]  pContext          - Pointer to the device context.
/// \param [out] ppGraphicsBinding - Address of the memory location where the pointer to the data blob
///                                  containing the graphics binding will be stored.
///
/// The function returns the data blob that contains the OpenXR graphics binding structure
/// (`XrGraphicsBindingVulkanKHR`, `XrGraphicsBindingD3D11KHR`, etc.).
/// The data blob should be used to create the OpenXR session, for example:
///
///     RefCntAutoPtr<IDataBlob> pGraphicsBinding;
///     GetOpenXRGraphicsBinding(m_pDevice, m_pImmediateContext, &pGraphicsBinding);
///
///     XrSessionCreateInfo sessionCI{XR_TYPE_SESSION_CREATE_INFO};
///     sessionCI.next     = pGraphicsBinding->GetConstDataPtr();
///     sessionCI.systemId = m_SystemId;
///     xrCreateSession(m_xrInstance, &sessionCI, &m_xrSession);
///
void DILIGENT_GLOBAL_FUNCTION(GetOpenXRGraphicsBinding)(IRenderDevice*  pDevice,
                                                        IDeviceContext* pContext,
                                                        IDataBlob**     ppGraphicsBinding);

/// Creates OpenXR debug utils messenger.
XrDebugUtilsMessengerEXT DILIGENT_GLOBAL_FUNCTION(CreateOpenXRDebugUtilsMessenger)(
    XrInstance                          xrInstance,
    XrDebugUtilsMessageSeverityFlagsEXT xrMessageSeverities);

/// Destroys OpenXR debug utils messenger.
XrResult DILIGENT_GLOBAL_FUNCTION(DestroyOpenXRDebugUtilsMessenger)(XrDebugUtilsMessengerEXT xrDebugUtilsMessenger);

/// Allocates OpenXR swapchain image data, i.e. an array of appropriate structures for each device
/// type (`XrSwapchainImageVulkanKHR`, `XrSwapchainImageD3D11KHR`, etc.).

/// \param [in]  DeviceType           - Type of the render device.
/// \param [out] ImageCount           - Number of images in the swapchain returned by OpenXR.
/// \param [out] ppSwapchainImageData - Address of the memory location where the pointer to the data blob
///                                     containing the swapchain image data will be stored.
///
/// The data blob data pointer should be passed to xrEnumerateSwapchainImages:
///
///     uint32_t SwapchainImageCount = 0;
///     xrEnumerateSwapchainImages(xrSwapchain, 0, &SwapchainImageCount, nullptr);
///     RefCntAutoPtr<IDataBlob> pSwapchainImageData;
///     AllocateOpenXRSwapchainImageData(m_DeviceType, SwapchainImageCount, &pSwapchainImageData);
///     xrEnumerateSwapchainImages(xrSwapchain, SwapchainImageCount, &SwapchainImageCount,
///                                pSwapchainImageData->GetDataPtr<XrSwapchainImageBaseHeader>());
///
void DILIGENT_GLOBAL_FUNCTION(AllocateOpenXRSwapchainImageData)(RENDER_DEVICE_TYPE DeviceType,
                                                                Uint32             ImageCount,
                                                                IDataBlob**        ppSwapchainImageData);

/// Returns the texture object that corresponds to the specified OpenXR swapchain image.

/// \param [in]  pDevice    - Pointer to the render device.
/// \param [in]  ImageData  - Pointer to the OpenXR swapchain image data returned by xrEnumerateSwapchainImages.
/// \param [in]  ImageIndex - Index of the swapchain image.
/// \param [in]  TexDesc    - Texture description.
/// \param [out] ppImage    - Address of the memory location where the pointer to the texture object
///                           will be stored.
///
/// The function creates a texture object that corresponds to the specified OpenXR
/// swapchain image.
///
/// Typically, ImageData should be allocated by AllocateOpenXRSwapchainImageData and
/// filled by `xrEnumerateSwapchainImages` (see Diligent::AllocateOpenXRSwapchainImageData):
///
///     RefCntAutoPtr<ITexture> pImage;
///     GetOpenXRSwapchainImage(pDevice, pSwapchainImageData->GetConstDataPtr<XrSwapchainImageBaseHeader>(),
///                             ImageIndex, Desc, &pImage);
///
/// `TexDesc` should be filled with the texture description that corresponds to the swapchain.
/// On Direct3D, the texture parameters will be derived from the swapchain resource.
/// On Vulkan, the texture description should be filled manually since Vulkan does not
/// provide a way to query texture parameters from the image.
///
void DILIGENT_GLOBAL_FUNCTION(GetOpenXRSwapchainImage)(IRenderDevice*                    pDevice,
                                                       const XrSwapchainImageBaseHeader* ImageData,
                                                       Uint32                            ImageIndex,
                                                       const TextureDesc REF             TexDesc,
                                                       ITexture**                        ppImage);

#include "../../../Primitives/interface/UndefRefMacro.h"

DILIGENT_END_NAMESPACE // namespace Diligent