Function wachspress_coordinates2 

pub fn wachspress_coordinates2(
    polygon: &Polygon2,
    point: DVec2,
    tolerance: Tolerance,
) -> Result<Vec<f64>, BarycentricError>

Wachspress coordinates of point in a strictly convex polygon, one weight per vertex (Wachspress 1975, in the determinant form of Meyer, Lee, Barr and Desbrun 2002).

For vertex i, w_i = C_i / (A_{i-1} * A_i) where C_i is twice the area of the corner triangle (v_{i-1}, v_i, v_{i+1}) and A_i is twice the area of (v_i, v_{i+1}, point); the result is w_i normalized to sum to one. Inside the polygon the weights are positive, smooth, and reproduce the point; on the boundary, within the linear tolerance, they are the boundary’s own linear interpolation. Outside the polygon they are the formula’s rational extension wherever it does not divide by zero. The polygon may wind either way.

Errors

BarycentricError::NonFinite, BarycentricError::TooFewVertices, BarycentricError::ShortEdge, BarycentricError::SelfIntersecting, BarycentricError::Degenerate for a polygon with no area to speak of, BarycentricError::NotConvex for a polygon that is not strictly convex, and BarycentricError::Undefined where a denominator vanishes (on the line through a non-adjacent edge, extended past its endpoints).