vector-networks

Delete and Heal for Vector Networks | Figma Blog (opens in new tab)

Figma’s “delete and heal” feature removes a vertex while preserving the surrounding shape as much as possible. What begins as a simple graph-editing operation becomes complex for curved segments and vector networks, where vertices may connect to many edges. Figma addresses this by fitting replacement Bézier curves and pairing edges according to their geometry. ## Basic Deletion and Healing - Standard deletion removes the selected vertex, its incident edges, and any fills that depend on those edges. - “Delete and heal” instead attempts to connect the neighboring vertices. - If a vertex touches only one edge, that edge is removed because no meaningful healing is possible. - Triangles and other small paths require special-case decisions about whether healing produces one edge or multiple edges. - The behavior differs between open and closed paths. ## Preserving Curvature - Curved segments are represented as cubic Bézier curves. - Deleting a vertex joins two cubic curves into one replacement curve. - Figma keeps the original endpoints fixed but adjusts the neighboring control handles to preserve the original curvature. - The algorithm: - Samples points along both original Bézier curves. - Treats the shared vertex as a single point. - Fits a new cubic Bézier curve through the resulting samples. - Figma uses a curve-fitting technique from Philip J. Schneider’s “An Algorithm for Automatically Fitting Digitized Curves,” published in *Graphics Gems*. ## Healing Vector Networks - Unlike traditional path-based editors, Figma models vector objects as undirected multigraphs with edge identity. - A vertex can therefore have more than two incident edges. - If the vertex has an odd number of connected edges, Figma removes all incident edges because no complete pairing is possible. - With an even number of edges, the edges are paired and replaced with new edges. - To determine which edges are “opposite,” the incident edges are sorted by their angles around the deleted vertex. - This graph-based approach allows delete-and-heal to work on branching vector networks, not just simple paths. Figma’s implementation combines graph topology, geometric pairing, Bézier sampling, and curve fitting to make deletion feel intuitive while retaining as much of the original design as possible.

Introducing Vector Networks | Figma Blog (opens in new tab)

Figma’s vector networks replace the traditional path model with a more flexible structure that lets users connect, split, and manipulate geometry naturally. The system remains compatible with existing cubic Bézier curves while improving direct editing, strokes, and fills. The result is a vector tool that behaves more like physical drawing and avoids several long-standing limitations of pen-based editors. ## Vector Networks vs. Traditional Paths - Traditional paths are chains of lines and curves connecting two endpoints. - Vector networks allow lines and curves between any points, without requiring one continuous chain. - Users can: - Connect any points together - Delete geometry anywhere - Split and recombine shapes naturally - Attach three or more lines to a single point - Stroke caps and joins work consistently, including at multi-line junctions. ## Direct Curve Manipulation - Existing vector tools typically use cubic Bézier curves with control handles positioned away from the curve. - Figma preserves Bézier compatibility but adds a bend tool for direct manipulation. - Holding Command on macOS allows users to drag the curve itself. - Figma automatically adjusts the underlying control handles to match the desired bend. ## More Intuitive Fills - Traditional vector engines use the winding number rule, where fill behavior depends on curve direction. - This makes fills difficult to understand because users generally cannot see whether curves were drawn clockwise or counterclockwise. - Vector networks automatically fill enclosed regions. - A paint bucket-style tool lets users toggle individual enclosed areas to create holes directly. - Developing this fill system was the most difficult part because earlier approaches required users to manually manage negative space. ## Design Through Iteration - Figma’s team initially explored more advanced curve types but chose to remain compatible with existing vector formats. - User studies showed that many people did not consciously notice vector networks; they simply found the tool behaved as expected. - The contrast became clear when users returned to conventional vector editors and encountered their limitations. - Despite many abandoned approaches and doubts during development, Figma concluded that vector networks offered a meaningful improvement over paths. Figma’s recommendation is implicit: vector editing should prioritize direct manipulation and intuitive geometry rather than forcing users to understand the underlying path mechanics. Vector networks preserve compatibility while making drawing, editing, strokes, and fills substantially more natural.