Place up to three points with your mouse, then see the coordinates of the mouse position.

Barycentric Coordinates can be converted from cartesian coordinates via the following formula $$\biggl[\begin{array}{c}\lambda_{1}\\\lambda_{2}\end{array}\biggr] = \biggl[\begin{array}{cc} x_1-x_3 & x_{2}- x_{3} \\ y_{1}-y_{3} & y_{2}-y_{3}\end{array}\biggr]^{-1}\cdot\biggl(\biggl[\begin{array}{c}x\\y\end{array}\biggr]-\biggl[\begin{array}{c}x_{3}\\y_{3}\end{array}\biggr]\biggr), \enspace \lambda_{3}=1-\lambda_{1}-\lambda_{2}$$ where for triangle vertices $$(x_1,y_1)$$, $$(x_2,y_2)$$, and $$(x_3,y_3)$$, selected by mouse clicks, and point to convert $$(x,y)$$, selected by mouse hover.