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https://github.com/visioncortex/vtracer.git
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Chris Tsang
ef9496f792
A new pipeline slot between curve fitting and composition: CurvePasses rewrite each fitted contour, so mosaic mode transforms every shared boundary segment exactly once and the tessellation stays seam-free by construction. SimplifyCurves re-fits each smooth run between corners with the fewest cubics within the tolerance (Schneider's algorithm via a current flo_curves — visioncortex's copy is pinned to an old one and block-splits at 200 points), with tangents from the chain's own ends, corners kept in place, junction endpoints pinned bit-for-bit, and rings seamed at their sharpest junction. Off by default; polylines pass through untouched. Cityscape at tolerance 1: 229 -> 138 KB stacked, 103 -> 36 KB watershed cutout, with render diffs under golden noise. CurveFitter now returns Vec<FittedGeom> (promoted from mosaic::fit) so stacked contours flow through the same pass machinery; the optimizer's SimplifyPass is renamed CleanupPass to free the word.
VTracer 1.0 Design Documents
VTracer is being rearchitected from a single hardcoded pipeline into a vectorization framework. These documents describe the target design.
| Document | Contents |
|---|---|
| architecture.md | Workspace layout, core IR, stage traits, pipeline driver, optimizer & SVG writer, CLI |
| mosaic.md | The seam-free cutout/mosaic mode: boundary-graph tracing and shared-edge curve fitting |
| bindings.md | Python (PyPI), wasm, and the new Node.js (npm) package |
| roadmap.md | Milestones and verification strategy |
Motivation
VTracer today (0.6.x) is a thin driver around the visioncortex crate: one pipeline (color clustering → per-cluster tracing → SVG string), a CLI, a pyo3 binding, and a web demo that duplicates the pipeline. The rewrite turns it into a framework with pluggable stages:
- Frontend — any algorithm that produces clusters/segmentation from a raster image
- Curve fitting backend — pluggable polyline→curve fitters (pixel, polygon, spline, future potrace-style)
- Color fitting — mapping cluster colors to final paints, including custom fixed palettes
- Optimizer — a pass pipeline that shrinks output (relative path syntax, shorthand commands, precision reduction)
- True mosaic cutout — a perfect, gapless tessellation with shared boundary geometry, replacing today's fake cutout (which re-clusters a re-rendered image and shows seams)
The project stays backend/CLI focused, and everything except image file I/O compiles to wasm32-unknown-unknown.
Decisions
visioncortexremains a dependency, wrapped behind traits. Development uses a path/[patch]dependency on the local checkout; API additions are committed to visioncortex directly and published as 0.8.x releases. Verified that everything the new design needs is already public: the fitting primitives (fit_points_with_bezier,find_corners,subdivide_keep_corners,reduce,PathSimplify::*) and cluster pixel access viaClustersView.- In-repo rewrite, clean break. New workspace layout, new API, version bump. Old CLI flags are kept only where they map naturally.
- Python binding stays (ported to the new API). The webapp GUI is dropped; a wasm library crate replaces it.
- New Node.js library published to npm, using the wasm build internally plus a native image reader (sharp).
Pipeline at a glance
┌───────────┐ ┌──────────────┐ ┌─────────────────────────────┐
raster ───▶ │ Frontend │ ─▶│ ColorFitter* │ ─▶│ Compositing │
image │ (segment) │ │ (palette, │ │ Stacked: closed outlines │
└───────────┘ │ quantize, │ │ Mosaic: boundary graph + │
│ merge) │ │ shared-edge fit │
└──────────────┘ └──────────────┬──────────────┘
│ CurveFitter
▼ (pixel/polygon/spline)
┌──────────────────────────────┐
SVG ◀──── │ VectorDoc ─ OptimizerPass* ─ │
│ SvgWriter │
└──────────────────────────────┘