1. A computer-implemented method comprising: performing, by a computer: generating a tessellated trimmed parametric surface based on a parametric surface and a trim curve, said generating comprising: tessellating the parametric surface to produce a set of polygons approximating the parametric surface; determining a first polygon of the set of polygons in which a first point on the trim curve is located; projecting a second point on the trim curve into a plane, wherein the plane is determined by the first polygon of the set of polygons; projecting a set of one or more additional polygons of the set of polygons into the plane; and determining a second polygon of the set of one or more additional polygons in which the second point on the trim curve is located.