‘Morphisms’* are bundles operations which alter the current state of a garment. They are mostly constructed out of of Euler operators, geometric transformations, and embedding of data into elements of the product (such as information about materials or ornaments).
Morphism always takes a full previous state as an input and targets a certain known ‘receptor’ in the garment. For example center front seam of an upper body garment requires a neckline and hemline to be present in the existing state, side seam requires an arm hole and hemline and so forth.
Morphisms are stored as unevaluated S-expressions, which makes them both human readable and intention preserving. For example a feature mid-layer might have a single morphism: '(translate-along shoulder-line arm-hole (* shoulder-length 0.1)), which will evaluate into something like (nurbs 3 '(0 1 2 3 4 5 6 7 8 9 10 11 12 13 14) point1 point2 point3...). From the former it is relatively easy to parse the intention, in the latter, the intention is lost.
* The word is not used in its exact mathematical meaning, but more colloquially.
Morphing operations are defined through geometric constraints which use the three primary axis and skin measurements as references. Calculations don't contain any absolute values, but adapt to the current state of the garment. For example, shouder line is a straight line starting from a point on the shoulder head seam, which is nearest to the anatomical shoulder point on the skin. On the other side it finishes on a point on a neckline seam, which is has minimum distance to a line along the x-axis from the shoulder point. Similarly side-seam is a straight line exiting from the lowest point on the armhole, with minimal variation along y-axis, until it reaches the hemline.
Most topological morphisms are combinations of two basic classes of operations: adding new circular edges, and connecting circular edges with straight lines. Circularity means the topological structure of the edge, not geometric shape. For example in the below set-in-armhole morphism, the shape of the arm hole is not circular (or even a continuous curve).
Circular and line additions are combined into larger operations, which create full features. For example feature 4-part-sleeve contains operations which first create a new circular edge an elbow line and connects it to existing arm-hole and wristline. The arm hole side's geometry is dictated by known chest-point and back-point, the forearm on wrist side is split so that the seam lines have maximal and minimal z-axis positions respectively.
Structural and material information is saved as edge, face or node data, which gets inherited in any future operations. For example a main fabric is saved in the first created face of a garment, and then gets inherited into all other faces when they are created.