Function captureViewportRenderThreadSafe

src/python/lfs/py_rendering.cpp:98–136

        }

        [[nodiscard]] std::optional<vis::ViewportRender> captureViewportRenderThreadSafe() {
            auto invoke_capture = []() -> std::optional<vis::ViewportRender> {
                return vis::capture_viewport_render();
            };

            auto* const viewer = get_visualizer();
            if (!viewer || viewer->isOnViewerThread()) {
                return invoke_capture();
            }
            if (!viewer->acceptsPostedWork()) {
                return std::nullopt;
            }

            auto promise = std::make_shared<std::promise<std::optional<vis::ViewportRender>>>();
            auto future = promise->get_future();
            auto completed = std::make_shared<std::atomic_bool>(false);

            auto finish = [promise, completed](std::optional<vis::ViewportRender> result) mutable {
                if (!completed->exchange(true)) {
                    promise->set_value(std::move(result));
                }
            };

            const bool posted = viewer->postWork(vis::Visualizer::WorkItem{
                .run =
                    [invoke_capture, finish]() mutable {
                        finish(invoke_capture());
                    },
                .cancel =
                    [finish]() mutable {
                        finish(std::nullopt);
                    }});
            if (!posted) {
                return std::nullopt;
            }

            nb::gil_scoped_release release;
            return future.get();
        }

        [[nodiscard]] core::PointCloud pointCloudFromMesh(const core::MeshData& mesh) {
            core::Tensor colors;