def exportNURBSCurve(curve, bbox=[(0,0), (1,1)]):
file_str = io.StringIO()
degree = curve.M
assert(degree <= 3)
assert(curve.prop3 == 1)
# print(curve)
# first convert nurbs to bezier
# TODO: assume the knot sequence has knot multiplicty degree + 1 at both end
b_knot, b_cpts = nurbs2bezier(curve.T[1:-1], [np.array(p) for p in curve.control_points], degree)
for p in b_cpts:
p[0:2] -= np.array(bbox[0])
p[0] /= bbox[1][0] - bbox[0][0]
p[1] /= bbox[1][1] - bbox[0][1]
file_str.write("M {},{}".format(b_cpts[0][0], b_cpts[0][1]))
first = True
for i in range((len(b_cpts) - 1) // degree):
print("-----")
cpts = []
for j in range(degree + 1):
newp = b_cpts[i*degree + j]
cpts.append(newp)
if degree == 1:
file_str.write(" L {},{}".format(cpts[1][0], cpts[1][1]))
continue
if degree == 2:
cpts = degRaiseFrom2(cpts)
for i,p in enumerate(cpts):
if first:
first = False
file_str.write(" C ")
elif i != 0:
file_str.write(" {},{}".format(p[0], p[1]))
return file_str.getvalue()
def exportNURBSSurface(surface):
file_str = io.StringIO()
degu = surface.M1
degv = surface.M2
#print(surface)
# first convert nurbs to bezier
# TODO: assume the knot sequence has knot multiplicty degree + 1 at both end
#print(len(surface.control_points), len(surface.W))
cpts = np.array([np.array([surface.control_points[i][0],
surface.control_points[i][1],
surface.control_points[i][2],
surface.W[i]]) for i in range(len(surface.W))])
cpts = cpts.reshape([ surface.K2 + 1, surface.K1 + 1, 4])
# 1rd direction
b_knot_u, b_cpts = nurbs2bezier(surface.T1[1:-1], [cpts[:,i] for i in range(surface.K1 + 1)], degu)
cpts = np.array(b_cpts)
b_knot_v, b_cpts = nurbs2bezier(surface.T2[1:-1], [cpts[:,i] for i in range(surface.K2 + 1)], degv)
cpts = np.array(b_cpts)
uvbbox = [(surface.U0, surface.V0), (surface.U1, surface.V1)]
total_bicubic_piece = 0
# TODO: assume the nurbs curve is indeed in bezier form
for piece_v in range((cpts.shape[0] - 1)//degv):
v_base = b_knot_v[piece_v * degv]
v_end = b_knot_v[piece_v * degv + degv]
for piece_u in range((cpts.shape[1] - 1)//degu):
u_base = b_knot_u[piece_u * degu]
u_end = b_knot_u[piece_u * degu + degu]
bcpts = np.zeros([degv + 1, degu + 1, 6])
for i in range(degv + 1):
for j in range(degu + 1):
idx_v = i + degv * piece_v
idx_u = j + degu * piece_u
p = cpts[idx_v][idx_u]
#file_str.write("v {} {} {} {}\n".format(p[0], p[1], p[2], p[3]))
uv = np.array((u_base + j / degu * (u_end - u_base), v_base + i / degv * (v_end - v_base)))
uv -= np.array(uvbbox[0])
uv[0] /= (uvbbox[1][0] - uvbbox[0][0])
uv[1] /= (uvbbox[1][1] - uvbbox[0][1])
#file_str.write("vt {} {}\n".format(uv[0], uv[1]))
bcpts[i][j] = np.array([p[0], p[1], p[2], p[3], uv[0], uv[1]])
# print(xyz,w,uv)
# convert bezier patch to bicubic
vpiece = 1 if degv <= 3 else 3
upiece = 1 if degu <= 3 else 3
_bcpts = convert2Cubic([bcpts[:,i] for i in range(degu+1)])
bcpts = np.array(_bcpts)
_bcpts = convert2Cubic([bcpts[:,i] for i in range(degv+1)])
bcpts = np.array(_bcpts)
for i in range(vpiece):
for j in range(upiece):
total_bicubic_piece += 1
for k in range(4):
for l in range(4):
p = bcpts[i*3 + k][j*3 + l]
file_str.write("v {} {} {} {}\n".format(p[0], p[1], p[2], p[3]))
file_str.write("vt {} {}\n".format(p[4], p[5]))
idx = 1
# for piece_v in range((cpts.shape[0] - 1)//degv):
# for piece_u in range((cpts.shape[1] - 1)//degu):
# file_str.write("p {} {}\n".format(degu, degv))
# for i in range((degu + 1)*(degv + 1)):
# file_str.write("{}/{}\n".format(idx, idx))
for i in range(total_bicubic_piece):
file_str.write("p {} {}\n".format(3, 3))
for i in range(16):
file_str.write("{}/{}\n".format(idx, idx))
idx+=1
return file_str.getvalue()
