The entire transformation architecture has been rewritten. Previously the x and y transformations where stored in the xaxis and yaxis instances. The problem with this approach is it only allows for separable transforms (where the x and y transformations don’t depend on one another). But for cases like polar, they do. Now transformations operate on x,y together. There is a new base class and two concrete implementations, and . The SeparableTransformation is constructed with the bounding box of the input (this determines the rectangular coordinate system of the input, ., the x and y view limits), the bounding box of the display, and possibly nonlinear transformations of x and y. The 2 most frequently used transformations, data coordinates -> display and axes coordinates -> display are available as and . See alignment_ which uses axes coords.