Files
test2/source/blender/gpu/vulkan/vk_context.hh
Jeroen Bakker 3885a37541 Vulkan: Initial OpenXR support
The Blender's VkInstance cannot be shared with OpenXR VkInstance. The
reason is a chicken and egg problem where OpenXR needs to be started
before Vulkan. OpenXR can add special vulkan specific requirements
(instance&device) that are only available when the user starts an OpenXR
session.

The goal implementation is to share memory between both instances using
[VK_KHR_external_memory](https://registry.khronos.org/vulkan/specs/latest/man/html/VK_KHR_external_memory.html) and related extensions. However this seems
to be a bridge to far as a initial step. Reason: There are not that many
samples/ guides and documentation to be found to handle the workflow that
we require. We want to do a smaller step by step approach to gain the needed
knowledge.

For that reason this PR does the most stupidest thing that can be done to
share memory between instances. Download the render result to CPU RAM share
the host pointer with the OpenXR instance which copies it to the swap chain.
Also the synchronization is done using wait idle commands.

<video src="attachments/32a0d69b-c3fa-4272-aea0-d207609afaaf" title="Screencast From 2025-03-18 11-16-17.webm" controls></video>

**Gaining knowledge**

- Experiment with `VK_KHR_external_memory_host` extension for uploading vertex buffers (not related to OpenXR).
- Import host pointer with `VK_KHR_external_memory_host`. This reduces the additional
  memcpy on OpenXR side.
- Export host pointer from Blender side from a mappable buffer.
- Replace host pointers with fd/dmabuf/winhandle
- Remove mappable buffer.

Ref #133718

Pull Request: https://projects.blender.org/blender/blender/pulls/133824
2025-03-27 16:57:51 +01:00

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/* SPDX-FileCopyrightText: 2022 Blender Authors
*
* SPDX-License-Identifier: GPL-2.0-or-later */
/** \file
* \ingroup gpu
*/
#pragma once
#include "BLI_utildefines.h"
#include "gpu_context_private.hh"
#include "GHOST_Types.h"
#include "render_graph/vk_render_graph.hh"
#include "vk_common.hh"
#include "vk_debug.hh"
#include "vk_descriptor_pools.hh"
#include "vk_resource_pool.hh"
namespace blender::gpu {
class VKFrameBuffer;
class VKVertexAttributeObject;
class VKBatch;
class VKStateManager;
class VKShader;
class VKThreadData;
enum RenderGraphFlushFlags {
NONE = 0,
RENEW_RENDER_GRAPH = 1 << 0,
SUBMIT = 1 << 1,
WAIT_FOR_COMPLETION = 1 << 2,
};
ENUM_OPERATORS(RenderGraphFlushFlags, RenderGraphFlushFlags::WAIT_FOR_COMPLETION);
class VKContext : public Context, NonCopyable {
private:
VkExtent2D vk_extent_ = {};
VkSurfaceFormatKHR swap_chain_format_ = {};
GPUTexture *surface_texture_ = nullptr;
void *ghost_context_;
/* Reusable data. Stored inside context to limit reallocations. */
render_graph::VKResourceAccessInfo access_info_ = {};
std::optional<std::reference_wrapper<VKThreadData>> thread_data_;
std::optional<std::reference_wrapper<render_graph::VKRenderGraph>> render_graph_;
public:
VKDiscardPool discard_pool;
const render_graph::VKRenderGraph &render_graph() const
{
return render_graph_.value().get();
}
render_graph::VKRenderGraph &render_graph()
{
return render_graph_.value().get();
}
VKContext(void *ghost_window, void *ghost_context);
virtual ~VKContext();
void activate() override;
void deactivate() override;
void begin_frame() override;
void end_frame() override;
void flush() override;
TimelineValue flush_render_graph(
RenderGraphFlushFlags flags,
VkPipelineStageFlags wait_dst_stage_mask = VK_PIPELINE_STAGE_NONE,
VkSemaphore wait_semaphore = VK_NULL_HANDLE,
VkSemaphore signal_semaphore = VK_NULL_HANDLE);
void finish() override;
void memory_statistics_get(int *r_total_mem_kb, int *r_free_mem_kb) override;
void debug_group_begin(const char *, int) override;
void debug_group_end() override;
bool debug_capture_begin(const char *title) override;
void debug_capture_end() override;
void *debug_capture_scope_create(const char *name) override;
bool debug_capture_scope_begin(void *scope) override;
void debug_capture_scope_end(void *scope) override;
void debug_unbind_all_ubo() override;
void debug_unbind_all_ssbo() override;
bool has_active_framebuffer() const;
void activate_framebuffer(VKFrameBuffer &framebuffer);
void deactivate_framebuffer();
VKFrameBuffer *active_framebuffer_get() const;
/**
* Ensure that the active framebuffer isn't rendering.
*
* Between `vkCmdBeginRendering` and `vkCmdEndRendering` the framebuffer is rendering. Dispatch
* and transfer commands cannot be called between these commands. They can call this method to
* ensure that the framebuffer is outside these calls.
*/
void rendering_end();
render_graph::VKResourceAccessInfo &reset_and_get_access_info();
/**
* Update the give shader data with the current state of the context.
*/
void update_pipeline_data(render_graph::VKPipelineData &r_pipeline_data);
void update_pipeline_data(GPUPrimType primitive,
VKVertexAttributeObject &vao,
render_graph::VKPipelineData &r_pipeline_data);
void sync_backbuffer(bool cycle_resource_pool);
static VKContext *get()
{
return static_cast<VKContext *>(Context::get());
}
VKDescriptorPools &descriptor_pools_get();
VKDescriptorSetTracker &descriptor_set_get();
VKStateManager &state_manager_get() const;
static void swap_buffers_pre_callback(const GHOST_VulkanSwapChainData *data);
static void swap_buffers_post_callback();
static void openxr_acquire_framebuffer_image_callback(GHOST_VulkanOpenXRData *data);
static void openxr_release_framebuffer_image_callback(GHOST_VulkanOpenXRData *data);
private:
void swap_buffers_pre_handler(const GHOST_VulkanSwapChainData &data);
void swap_buffers_post_handler();
void openxr_acquire_framebuffer_image_handler(GHOST_VulkanOpenXRData &data);
void openxr_release_framebuffer_image_handler(GHOST_VulkanOpenXRData &data);
void update_pipeline_data(VKShader &shader,
VkPipeline vk_pipeline,
render_graph::VKPipelineData &r_pipeline_data);
};
BLI_INLINE bool operator==(const VKContext &a, const VKContext &b)
{
return static_cast<const void *>(&a) == static_cast<const void *>(&b);
}
} // namespace blender::gpu