v130 · graphics

WebGPU: Dual source blending

Functionality added to the WebGPU spec after its first shipment in a browser.

concepts

  1. Dual-source blending probe

    Feature-detect the GPU adapter for dual-source-blending, build a minimal pipeline with the new src1 blend factors, and report what the engine ships.

  2. Subpixel text shader

    The canonical use case — LCD subpixel-AA text. Side-by-side: monochrome AA (grey edges) vs simulated dual-source subpixel AA (crisp edges with per-channel coverage), plus the WGSL that drives the GPU pipeline.

  3. Blend equation studio

    Five distinct use cases (subpixel text, premultiplied compositing, custom RGB-mask effects, two-pass lighting, color-channel correction). Each emits the WGSL fragment outputs, the WebGPU blend-state JSON, the resolved equation, and side-by-side visual previews (dst only / single-source / dual-source).

  4. Alpha masking

    Pick foreground/background colours and a mask pattern (radial, checkerboard, diagonal, ring). Side-by-side: dual-source blend with per-pixel mask vs standard uniform alpha — showing why one draw call with src1 replaces a two-pass mask pipeline.

why it shipped

The “dual-source-blending” GPU feature adds additional blend factors and the WGSL @blend_src attribute to allow a fragment shader to blend two color outputs into a single output buffer.

references