Simple constraint

Simple chain link

If p₁ follows p₀, then p₁ gets its coordinates from the following set of equations:

Calculate the length difference

$l={\sqrt {(p1_{x}-p0_{x})^{2}+(p1_{y}-p0_{y})^{2}}}$

, and how much to add with given radius, ${\mathbf {r}}$

$dx=\left({\frac {p1_{x}-p0_{x}}{l}}\right)*r-(p1_{x}-p0_{x})$

$dy=\left({\frac {p1_{y}-p0_{y}}{l}}\right)*r-(p1_{y}-p0_{y})$

, where

$p1_{x}^{1}=p1_{x}+dx$

$p1_{y}^{1}=p1_{y}+dy$

are the new points.