A flat Canvas2D companion to the 3D Gestalt Grouping Principles simulation. Gestalt grouping — proximity, similarity, closure, continuity and common fate — is inherently a two-dimensional visual-design phenomenon: elements laid out on a plane, grouped by spacing, colour, completed contours, smooth paths or shared motion. This version renders each principle directly on a 2D canvas with a single adjustable strength control per principle, so the perceptual flip is immediate and legible even on small screens.