// based on https://en.wikipedia.org/wiki/De_Boor%27s_algorithm
/// <summary>Returns the point at the given De-Boor recursion depth, knot interval and parameter space u-value</summary>
/// <param name="k">The index of the knot interval our u-value is inside</param>
/// <param name="u">A value in parameter space. Note: this value has to be within the internal knot interval</param>
public Vector2 Eval(int k, float u)
{
// make sure our buffer is ready
if (evalBuffer == null || evalBuffer.Length != degree + 1)
{
evalBuffer = new Vector2[degree + 1];
}
// populate points in the buffer
for (int i = 0; i < degree + 1; i++)
{
evalBuffer[i] = points[i + k - degree];
}
// calculate each layer until we've got only one point left
for (int r = 1; r < degree + 1; r++)
{
for (int j = degree; j > r - 1; j--)
{
float alpha = Mathfs.InverseLerpSafe(knots[j + k - degree], knots[j + 1 + k - r], u);
evalBuffer[j] = Vector2.LerpUnclamped(evalBuffer[j - 1], evalBuffer[j], alpha);
}
}
return(evalBuffer[degree]);
}
