zero_readback

Zero-Readback: Standard RenderDirect Path

GPU-direct rendering — all content rendered in a single GPU pass via RenderDirect. Zero CPU readback, zero pixmap upload.

APIs Demonstrated

• FillRectCPU — CPU-only background fill (bypasses GPU SDF accelerator)
• RenderDirect — single FlushGPUWithView pass to swapchain surface
• GPU SDF circles (Tier 1) — rendered directly to surface
• GPU GlyphMask text (Tier 6) — pixel-perfect hinted text

Architecture

canvas.Draw(fn)                  → BeginAcceleratorFrame + draw all content
canvas.Render(dc.RenderTarget()) → RenderDirect → FlushGPUWithView → surface

All visible content is GPU-rendered. CPU pixmap is not uploaded.

Run

go build -o zero_readback.exe . && ./zero_readback.exe

Compare

See ../zero_readback_manual/ for the manual pipeline that separates CPU and GPU content — the path used by ui/desktop.go for retained-mode compositing (ADR-006).