78 lines
2.5 KiB
C++
78 lines
2.5 KiB
C++
/*
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* Copyright 2022 Google LLC
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*
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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*/
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#ifndef skgpu_graphite_DawnBackendContext_DEFINED
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#define skgpu_graphite_DawnBackendContext_DEFINED
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#include "include/core/SkTypes.h"
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#include "webgpu/webgpu_cpp.h" // NO_G3_REWRITE
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#include <memory>
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namespace skgpu::graphite {
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class Context;
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struct ContextOptions;
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/**
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* WebGPU needs to allow the main thread loop to run to detect GPU progress. Dawn native has a
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* function wgpu::Instance::ProcessEvents, not (currently) present in WebGPU, that can be used to
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* detect GPU progress.
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*
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* When compiling using Emscripten/WASM the -s ASYNCIFY option can be used to yield. E.g.:
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*
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* EM_ASYNC_JS(void, asyncSleep, (), {
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* await new Promise((resolve, _) = > {
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* setTimeout(resolve, 0);
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* })
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* });
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*
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* WebGPUTickFunction(wgpu::Device&) { asyncSleep(); }
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*
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* If no DawnTickFunction is provided then the graphite::Context will be "non-yielding". This
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* implies the following restrictions on the Context:
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*
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* 1) SyncToCpu::kYes is disallowed as a parameter to Context::submit.
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* 2) The client must guarantee that GPU work has completed before destroying Context as Context
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* cannot await the work completion in its destructor. Context reports whether it is awaiting
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* GPU work completion via Context::hasUnfinishedGpuWork().
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*
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* Using a non-yielding Context makes it possible to build and run Graphite/Dawn on WebGPU without
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* -s ASYNCIFY.
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*/
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using DawnTickFunction = void(const wgpu::Instance& device);
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#if !defined(__EMSCRIPTEN__)
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SK_API inline void DawnNativeProcessEventsFunction(const wgpu::Instance& instance) {
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instance.ProcessEvents();
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}
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#endif
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// The DawnBackendContext contains all of the base Dawn objects needed by the graphite Dawn
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// backend. The client will create this object and pass it into the Context::MakeDawn factory call
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// when setting up Skia.
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struct SK_API DawnBackendContext {
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wgpu::Instance fInstance;
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wgpu::Device fDevice;
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wgpu::Queue fQueue;
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// See comment on DawnTickFunction.
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DawnTickFunction* fTick =
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#if defined(__EMSCRIPTEN__)
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nullptr;
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#else
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DawnNativeProcessEventsFunction;
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#endif
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};
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namespace ContextFactory {
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SK_API std::unique_ptr<Context> MakeDawn(const DawnBackendContext&, const ContextOptions&);
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} // namespace ContextFactory
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} // namespace skgpu::graphite
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#endif // skgpu_graphite_DawnBackendContext_DEFINED
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