Watertight spline modeling for additive manufacturing

A non-transitory computer-readable memory medium storing program instructions which, when executed by a processor, cause the processor to:

• receive a geometrically watertight computer-aided design (CAD) spline model of an object;
• for each of a plurality of respective layers of the object:
• perform an intersection routine of a respective plane of the layer with the geometrically watertight CAD spline model to directly determine a respective smooth contour curve, wherein, for each of the plurality of respective layers, the smooth contour curve comprises a spline curve representing an intersection of the respective plane of the respective layer with the geometrically watertight CAD spline model;
• and
• determine a respective plurality of hatch curves within the respective plane and interior to the respective smooth contour curve;
• store the smooth contour curves and the pluralities of hatch curves in the non-transitory computer-readable memory medium;
• and
• provide printing instructions to an additive manufacturing (AM) printer to sequentially deposit AM material on each of the plurality of layers according to the smooth contour curves and the pluralities of hatch curves.