Given 2 FPoints, point1 and point2, calculate an interpolated y value for a new point, xpos, between the 2. Returns the FPoint xpos with the new y value. Pinches upward, adding points to the given layer from the the one above it where the layer ends. This method takes a floating point range and a layer number and returns ALL points in layer within that range. Deletes both velocity and layer Points from layer in given range.
Calls extend method for each layer.
Given a layer and an xmin and xmax extends to model limits. Returns a copy of itself.