Native viewport pixels (gap #2)¶
Status: Phase A shipped; Phase B scaffold (runtime stub + LIG_WGPU_READBACK=1) — in-tree wgpu-rs swapchain readback not yet wired.
Phase A: lig.kernel.present_blit_rgba8 kid=3 via lig_present_blit_paint_summary.
Phase B (scaffold): lig_present_wgpu_readback_paint_summary / li_rt_lig_wgpu_readback_stub sets native_pixel_source=3 when LIG_WGPU_READBACK=1 and LIG_HOST_PRESENT=1. lig.kernel.present_wgpu_readback kid=4 dispatches via li_rt_lig_kernel_run. Studio vertical demo exit codes 54 (readback paint fail) / 55 (wrong pixel source).
Phase B (future): in-tree wgpu-rs swapchain texture readback (no env stub).
Sources: 0 none, 1 external CPU host, 2 paint blit, 3 wgpu readback.
| Env | Present path | native_pixel_source |
|---|---|---|
LIG_HOST_PRESENT=1 (default blit) | lig_present_blit_paint_summary | 2 paint blit |
LIG_HOST_PRESENT=1 + LIG_WGPU_READBACK=1 | lig_present_wgpu_readback_paint_summary | 3 wgpu readback (stub) |
lig_present_blit_paint_summary delegates to the readback stub when LIG_WGPU_READBACK=1.