agg-gui-wgpu

Hardware-accelerated wgpu renderer for agg-gui.

WgpuGfxCtx implements agg-gui's DrawCtx on top of wgpu, so the same widget tree that renders through the AGG software rasterizer renders on the GPU instead.

What's in here

• WgpuGfxCtx — the DrawCtx implementation. Fills, strokes, gradients, images, LCD subpixel text, compositing layers (transient and retained), and clipping, accumulated as deferred draw commands and flushed to a single command encoder in end_frame.
• custom_render — the hook a widget uses to run its own wgpu render pass(es) interleaved with the 2-D stream, on the same surface or layer texture. This is how a 3-D viewport widget plugs in.
• ssaa::SsaaFramebuffer — offscreen supersampled colour + depth target with a blit-to-surface that reuses the shared textured-quad pipeline.
• Screenshot capture — GPU-resident capture, full-surface read-back, and scaled / region read-back (both blocking for native Save/Copy and poll-based for the browser, where a blocking map would deadlock).
• gpu::Gpu — the device + surface bundle a native shell builds its swap chain on, including the surface-acquire recovery policy and the max-texture-dimension clamp.

Usage

let mut ctx = WgpuGfxCtx::new(device, queue, surface_format, width, height);

// each frame
ctx.reset(width, height);
ctx.begin_frame(surface_view);
app.paint(&mut ctx);
ctx.end_frame();
ctx.present(surface_texture); // releases the ctx's frame handles, then presents

Always present via ctx.present(...) rather than surface_texture.present(): the ctx may hold a clone of the back buffer for screenshots, and on DX12 a clone that outlives present makes the next swap-chain resize fail.

Turn-key platform shells (winit event loop, browser canvas + rAF loop) live in the agg-gui repo's demo-wgpu crate.

License

MIT