Why SVG Path Interpolation Fails for Rotating Shapes and How to Fix It

Design engineer James Coombs spent a week diagnosing why a seemingly straightforward SVG animation between two illustration states produced broken, exploding-fragment visuals. The core problem is that interpolating raw path coordinates works for translations but fails for rotations, since points should travel arcs governed by sine and cosine, not straight lines. Rather than animating hundreds of individual coordinates, Coombs found the correct approach is to describe the entire rigid motion — rotation, scale, and translation — as a single transform matrix applied to the whole shape group. He solved this using a least-squares fit based on the Procrustes shape-alignment problem, requiring only four unknowns and no external math library. He also flagged a separate build-pipeline issue that corrupts SVG shapes before any morphing library even processes them, compounding the visual breakdown.