# Vue Constrained Drag

from Red Blob Games
13 Jan 2023

I'm experimenting with constrained dragging for https://alex-kreitzberg.github.io/Notes/TechnicalArt/Serifs/[1] . I have previously made some constrained dragging experiments. Here, The first diagram treats the three control points as having cartesian coordinates. In the second diagram I treat the two side control points as polar coordinates that share a single radius but have their own angles. In the third diagram I treat the left and center points as cartesian and the right point as polar, using the radius from the left point.

In the second diagram, when you drag `L` or `R`, I calculate the vector of that point relative to `C`, then convert that to polar coordinates to set the radius and angle. The downside is that when you drag `C`, drags the other two with you. Not sure what to think about that.

In the third diagram, only `R` is constrained, and it only sets the angle. It uses the radius calculated from `L`.

Source: vue-constrained-drag.js