InteropFence.hpp File Reference

Backend-uniform fence between QRhi command-buffer + CUDA stream. More...

Detailed Description

Backend-uniform fence between QRhi command-buffer + CUDA stream.

Vendor-direct video paths (AJA, Magewell, Rivermax, ...) need to be sure the GPU has finished writing a buffer before the peer device DMA-reads it. The synchronisation primitive differs by graphics API:

• D3D11 : no-op. The immediate context flush done at endOffscreenFrame is sufficient; CUDA mapped resources share the same queue.
• OpenGL : glFinish(). CPU-stalls but cheap when called once per frame at 25-60 Hz, and required because GL+CUDA buffer interop has no native fence path on every driver.
• D3D12 : ID3D12Fence shared with CUDA via cuda_interop_import_d3d12_fence
  • cuda_interop_wait_semaphore — stub today.
• Vulkan : a ring of exportable binary VkSemaphores (OPAQUE_FD / OPAQUE_WIN32) imported into CUDA via cuda_interop_import_vulkan_semaphore + cuda_interop_wait_semaphore.

Per-frame lifecycle on Vulkan (and on D3D12 once it is real):

// inside offscreen frame, after compute dispatch: fence.signalAfterEncode(cb, ++value); // outside the frame, before handing the buffer to the peer: fence.waitOnCuda(value);

Keeps the glFinish / D3D11-immediate-context-flush handling in one place instead of open-coded in each per-backend output path, and gives a stable hook for the D3D12 path when it lands.

Go to the source code of this file.

Classes
struct	score::gfx::interop::InteropFence
	Backend-uniform fence interface. Per-vendor adapters hold one instance, signal it after the per-frame compute dispatch, wait on it from CUDA before peer DMA. More...

Namespaces
namespace	score
	Base toolkit upon which the software is built.
namespace	score::gfx
	Graphics rendering pipeline for ossia score.

Functions
std::unique_ptr< InteropFence >	score::gfx::interop::makeInteropFence (QRhi &rhi)
	Factory. Returns the right concrete impl for rhi's backend. Caller still needs to init() the returned fence. Never null — unsupported backends return a stub whose valid() is false.