Python: headless viewer, vsync control, pipelined frame capture#11
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sebcrozet merged 3 commits intoJul 16, 2026
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…thon) The windowed capture loop was vsync-locked: kiss3d's swapchain defaults to AutoVsync and the blocking per-frame snap_rgb() readback defeats frame pipelining, so each render_frame+render iteration ate ~2 vblanks (~30 fps at 60 Hz) no matter how fast the GPU was. Fixes, exposed through nexus3d: - NexusViewer(width, height, headless=True): no OS window, no swapchain — frames render into an off-screen texture (kiss3d headless Window), never throttled by the display and usable without a display server. - NexusViewer.set_vsync(enabled)/vsync(): uncap a windowed viewer instead. - NexusViewer.render_async()/render_flush(): pipelined capture — returns the previous frame while this frame's GPU->CPU copy runs in the background (one frame of latency; flush collects the last frame). Cube-drop capture at 640x480: 33.1 -> 92.1 gen-fps (GPU physics), 26.5 -> 37.5 (Rapier CPU backend). Requires kiss3d feat/headless-capture-pipeline (new_headless_with_setup + snap_begin/snap_finish).
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Stacked on #8 (which stacks on #7) — merge order: #7 → #8 → this. After those merge, this PR reduces to its single commit (
feat: headless viewer, vsync control, and pipelined frame capture (Python)); until then the diff below includes their changes.New capture API in the
nexus3dPython bindings:NexusViewer(..., headless=True)— no OS window, no swapchain: frames render into an off-screen texture, never throttled by display vsync, and it works without a display server.set_vsync(enabled)/vsync()— uncap a windowed viewer instead.snap_rgb_async()/snap_rgb_flush()— pipelined capture: returns the previous frame while the current frame's GPU→CPU copy runs in the background (one frame of latency; flush collects the last frame).Why: the windowed capture loop was vsync-locked at ~30 fps — the swapchain defaults to Fifo and the blocking per-frame
snap_rgb()readback defeats frame pipelining, so each iteration ate ~2 vblanks regardless of GPU load. Headless + pipelined readback reaches 92 gen-fps at 640×480 (GPU physics; 37.5 with the Rapier CPU backend) on an RTX 5080, up from 33.🤖 Generated with Claude Code