279   ld hei = 2 * zz;  in build_stair()  local
306           hs[0] = point31(-xx, -xx, hei);  in build_stair()
307           hs[1] = point31(-xx, +xx, hei);  in build_stair()
308           hs[2] = point31(+xx, +xx, hei);  in build_stair()
309           hs[3] = point31(+xx, -xx, hei);  in build_stair()
312           hs[0] = point31(-xx, -xx, -hei);  in build_stair()
313           hs[1] = point31(-xx, +xx, -hei);  in build_stair()
314           hs[2] = point31(+xx, +xx, -hei);  in build_stair()
315           hs[3] = point31(+xx, -xx, -hei);  in build_stair()
319           hs[0] = T * point31(+xx, -xx, -hei);  in build_stair()
320           hs[1] = T * point31(+xx, +xx, -hei);  in build_stair()
321           hs[2] = T * point31(+xx, +xx, +hei);  in build_stair()
322           hs[3] = T * point31(+xx, -xx, +hei);  in build_stair()
326           hs[0] = T * point31(+xx, -xx, -hei);  in build_stair()
327           hs[1] = T * point31(+xx, +xx, -hei);  in build_stair()
328           hs[2] = to_rot(eupush(C0 + shift) * to_heis(T * point31(-xx, +xx, -hei)));  in build_stair()
329           hs[3] = to_rot(eupush(C0 + shift) * to_heis(T * point31(-xx, -xx, -hei)));  in build_stair()
334           hs[0] = to_rot(eupush(C0 - lshift) * to_heis(T * point31(-xx, +xx, hei)));  in build_stair()
335           hs[1] = to_rot(eupush(C0 - lshift) * to_heis(T * point31(-xx, -xx, hei)));  in build_stair()
336           hs[2] = T * point31(+xx, -xx, hei);  in build_stair()
337           hs[3] = T * point31(+xx, +xx, hei);  in build_stair()