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| 1 | +/* |
| 2 | + * Copyright 2026 Diligent Graphics LLC |
| 3 | + * |
| 4 | + * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | + * you may not use this file except in compliance with the License. |
| 6 | + * You may obtain a copy of the License at |
| 7 | + * |
| 8 | + * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | + * |
| 10 | + * Unless required by applicable law or agreed to in writing, software |
| 11 | + * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | + * See the License for the specific language governing permissions and |
| 14 | + * limitations under the License. |
| 15 | + * |
| 16 | + * In no event and under no legal theory, whether in tort (including negligence), |
| 17 | + * contract, or otherwise, unless required by applicable law (such as deliberate |
| 18 | + * and grossly negligent acts) or agreed to in writing, shall any Contributor be |
| 19 | + * liable for any damages, including any direct, indirect, special, incidental, |
| 20 | + * or consequential damages of any character arising as a result of this License or |
| 21 | + * out of the use or inability to use the software (including but not limited to damages |
| 22 | + * for loss of goodwill, work stoppage, computer failure or malfunction, or any and |
| 23 | + * all other commercial damages or losses), even if such Contributor has been advised |
| 24 | + * of the possibility of such damages. |
| 25 | + */ |
| 26 | + |
| 27 | +#pragma once |
| 28 | + |
| 29 | +/// \file |
| 30 | +/// CompositorServices session wrapper for visionOS. |
| 31 | + |
| 32 | +/// `CompositorServicesSession` encapsulates the visionOS frame protocol (frame query, update, |
| 33 | +/// timing wait, drawable iteration, present) and the optional ARKit world-tracking session, |
| 34 | +/// exposing a small, idiomatic C++ API on top of the C/Objective-C `CompositorServices` |
| 35 | +/// framework. |
| 36 | + |
| 37 | +#include <functional> |
| 38 | +#include <memory> |
| 39 | + |
| 40 | +#include "../../GraphicsEngine/interface/RenderDevice.h" |
| 41 | +#include "../../GraphicsEngine/interface/DeviceContext.h" |
| 42 | +#include "../../../Primitives/interface/BasicTypes.h" |
| 43 | +#include "../../../Common/interface/BasicMath.hpp" |
| 44 | +#include "../../../Common/interface/RefCntAutoPtr.hpp" |
| 45 | + |
| 46 | +namespace Diligent |
| 47 | +{ |
| 48 | + |
| 49 | +/// High-level wrapper around the visionOS CompositorServices frame protocol. |
| 50 | + |
| 51 | +/// The session owns: |
| 52 | +/// - a `cp_layer_renderer_t` received from the SwiftUI `CompositorLayer` entry point; |
| 53 | +/// - an optional ARKit world-tracking session that supplies device anchors for each drawable; |
| 54 | +/// - references to the Diligent device and immediate context used for wrapping drawable |
| 55 | +/// textures and presenting drawables. |
| 56 | +/// |
| 57 | +/// `cp_layer_renderer_t` and `cp_drawable_t` are exposed as opaque `void*` pointers so that |
| 58 | +/// consumers do not need to include `<CompositorServices/CompositorServices.h>` and can be |
| 59 | +/// compiled as plain C++ |
| 60 | +class CompositorServicesSession |
| 61 | +{ |
| 62 | +public: |
| 63 | + /// Initializes the session and, optionally, starts the ARKit world-tracking session. |
| 64 | + |
| 65 | + /// \param[in] pRenderer - Layer renderer (`cp_layer_renderer_t`) from the SwiftUI |
| 66 | + /// `CompositorLayer` entry point, passed as an opaque |
| 67 | + /// pointer. Must not be null. |
| 68 | + /// \param[in] pDevice - Diligent render device. Must not be null. |
| 69 | + /// \param[in] pContext - Diligent immediate context. Must not be null. |
| 70 | + /// \param[in] EnableWorldTracking - When `true`, an ARKit world-tracking session is started |
| 71 | + /// and used to attach device anchors to every drawable. |
| 72 | + /// When `false`, the scene is rigidly attached to the |
| 73 | + /// headset. |
| 74 | + CompositorServicesSession(void* pRenderer, |
| 75 | + IRenderDevice* pDevice, |
| 76 | + IDeviceContext* pContext, |
| 77 | + bool EnableWorldTracking = true); |
| 78 | + |
| 79 | + ~CompositorServicesSession(); |
| 80 | + |
| 81 | + // clang-format off |
| 82 | + CompositorServicesSession (const CompositorServicesSession&) = delete; |
| 83 | + CompositorServicesSession ( CompositorServicesSession&&) = delete; |
| 84 | + CompositorServicesSession& operator=(const CompositorServicesSession&) = delete; |
| 85 | + CompositorServicesSession& operator=( CompositorServicesSession&&) = delete; |
| 86 | + // clang-format on |
| 87 | + |
| 88 | + /// Drives a single CompositorServices frame from start to finish. |
| 89 | + |
| 90 | + /// Handles the full frame protocol mandated by visionOS: |
| 91 | + /// 1. Queries the next frame from the layer renderer. |
| 92 | + /// 2. Wraps app-side state updates in `cp_frame_start_update` / `cp_frame_end_update` |
| 93 | + /// by invoking `Update`. |
| 94 | + /// 3. Predicts timing after the update phase and waits until the compositor's optimal |
| 95 | + /// input time. |
| 96 | + /// 4. Enters the submission phase, iterates over all drawables, attaches a device anchor |
| 97 | + /// (when world tracking is enabled) and invokes `RenderDrawable` for each. |
| 98 | + /// 5. Ends the submission phase. |
| 99 | + /// |
| 100 | + /// All null / cancelled-frame paths are handled internally. |
| 101 | + /// |
| 102 | + /// `RenderDrawable` receives an opaque `cp_drawable_t` pointer and is responsible for |
| 103 | + /// setting up render targets, drawing the scene and calling `PresentDrawable` on the |
| 104 | + /// session. |
| 105 | + /// |
| 106 | + /// Either callback may be empty. |
| 107 | + /// |
| 108 | + /// \param[in] Update - Callback invoked during the update phase of the frame. |
| 109 | + /// \param[in] RenderDrawable - Callback invoked once per drawable during the submission |
| 110 | + /// phase of the frame. |
| 111 | + void RenderFrame(std::function<void()> Update, |
| 112 | + std::function<void(void* pDrawable)> RenderDrawable); |
| 113 | + |
| 114 | + /// Returns the number of views (eyes) in a drawable (typically 2 for stereo rendering). |
| 115 | + |
| 116 | + /// \param[in] pDrawable - Opaque `cp_drawable_t` pointer. |
| 117 | + Uint32 GetViewCount(void* pDrawable) const; |
| 118 | + |
| 119 | + /// Wraps the Metal color texture of a drawable view as a Diligent texture. |
| 120 | + |
| 121 | + /// \param[in] pDrawable - Opaque `cp_drawable_t` pointer. |
| 122 | + /// \param[in] ViewIndex - Zero-based view index. |
| 123 | + /// |
| 124 | + /// \return A reference to the Diligent texture, or null on failure. |
| 125 | + RefCntAutoPtr<ITexture> GetColorSwapchainImage(void* pDrawable, Uint32 ViewIndex); |
| 126 | + |
| 127 | + /// Wraps the Metal depth texture of a drawable view as a Diligent texture. |
| 128 | + |
| 129 | + /// \param[in] pDrawable - Opaque `cp_drawable_t` pointer. |
| 130 | + /// \param[in] ViewIndex - Zero-based view index. |
| 131 | + /// |
| 132 | + /// \return A reference to the Diligent texture, or null on failure. |
| 133 | + RefCntAutoPtr<ITexture> GetDepthSwapchainImage(void* pDrawable, Uint32 ViewIndex); |
| 134 | + |
| 135 | + /// Returns the reverse-Z projection matrix for a view in a drawable. |
| 136 | + |
| 137 | + /// The compositor mandates reverse-Z depth: the matrix maps the near plane to 1 and the |
| 138 | + /// far plane to 0. Clear the depth buffer to 0 and use `COMPARISON_FUNC_GREATER_EQUAL` |
| 139 | + /// in the PSO. |
| 140 | + /// |
| 141 | + /// \param[in] pDrawable - Opaque `cp_drawable_t` pointer. |
| 142 | + /// \param[in] ViewIndex - Zero-based view index. |
| 143 | + /// \param[in] NearZ - Near clipping plane distance. |
| 144 | + /// \param[in] FarZ - Far clipping plane distance. |
| 145 | + float4x4 GetProjectionMatrix(void* pDrawable, Uint32 ViewIndex, float NearZ, float FarZ) const; |
| 146 | + |
| 147 | + /// Returns the world-to-eye view matrix for a view in a drawable. |
| 148 | + |
| 149 | + /// When world tracking is enabled and the ARKit session has produced at least one anchor, |
| 150 | + /// the matrix accounts for the device pose in the world. Otherwise it yields a drawable- |
| 151 | + /// local view matrix (scene rigidly attached to the headset). |
| 152 | + /// |
| 153 | + /// \param[in] pDrawable - Opaque `cp_drawable_t` pointer. |
| 154 | + /// \param[in] ViewIndex - Zero-based view index. |
| 155 | + float4x4 GetViewMatrix(void* pDrawable, Uint32 ViewIndex) const; |
| 156 | + |
| 157 | + /// Encodes a present command for the drawable into the immediate context's Metal command |
| 158 | + /// buffer. |
| 159 | + |
| 160 | + /// Call after issuing all draw calls for the drawable, before `Flush`. |
| 161 | + /// |
| 162 | + /// \param[in] pDrawable - Opaque `cp_drawable_t` pointer. |
| 163 | + void PresentDrawable(void* pDrawable); |
| 164 | + |
| 165 | +private: |
| 166 | + struct Impl; |
| 167 | + std::unique_ptr<Impl> m_Impl; |
| 168 | +}; |
| 169 | + |
| 170 | +} // namespace Diligent |
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