Simple constraint
If p1 follows p0, then p1 gets its coordinates from the following set of equations:
Failed to parse (Conversion error. Server ("/media/api/rest_") reported: "Cannot get mml. TeX parse error: Double subscripts: use braces to clarify"): {\displaystyle d_{x}=p_{0}_{x}-p_{1}_{x}d_{y}=p_{0}_{y}-p_{1}_{y}l_{1}=d_{x}^{2}+d_{y}^{2}p_{1}_{d}x=d_{x}/l_{1}*r-d_{x}p_{1}_{d}y=d_{y}/l_{1}*r-d_{y},andfinallyp_{1}_{x}+=p_{1}_{d}xp_{1}_{y}+=p_{1}_{d}y}