Three see-through blobs share seven dots, but each bends between them by its own rule. Drag a dot and each blob shows its handles, the hidden arms that steer its curve. On both sides, pink stays near the dashed line, orange swings out, blue bulges widest. Uncheck a color to hide its blob.
The source code is at github.com/KirillOsenkov/LiveGeometry. It is written in .NET and Avalonia.