def derivatives_data_array(self, us, vs):
surf_vertices = self.evaluate_array(us, vs)
derivatives = self.derivatives_list(us, vs)
# derivatives[i][j][k] = derivative w.r.t U j times, w.r.t. V k times, at i'th pair of (u, v)
du = derivatives[:, 1, 0]
dv = derivatives[:, 0, 1]
return SurfaceDerivativesData(surf_vertices, du, dv)
def derivatives_data_array(self, us, vs):
numerator, denominator = self.fraction(0, 0, us, vs)
surface = numerator / denominator
numerator_u, denominator_u = self.fraction(1, 0, us, vs)
numerator_v, denominator_v = self.fraction(0, 1, us, vs)
surface_u = (numerator_u - surface * denominator_u) / denominator
surface_v = (numerator_v - surface * denominator_v) / denominator
return SurfaceDerivativesData(surface, surface_u, surface_v)