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# -*- coding: utf-8 -*-
# -----------------------------------------------------------------------------
# Copyright (c) 2014, Nicolas P. Rougier
# Distributed under the (new) BSD License. See LICENSE.txt for more info.
# -----------------------------------------------------------------------------
import numpy as np
from .normals import normals
def surface(func, umin=0, umax=2 * np.pi, ucount=64, urepeat=1.0,
vmin=0, vmax=2 * np.pi, vcount=64, vrepeat=1.0):
"""
Computes the parameterization of a parametric surface
func: function(u,v)
Parametric function used to build the surface
"""
vtype = [('position', np.float32, 3),
('texcoord', np.float32, 2),
('normal', np.float32, 3)]
itype = np.uint32
# umin, umax, ucount = 0, 2*np.pi, 64
# vmin, vmax, vcount = 0, 2*np.pi, 64
vcount += 1
ucount += 1
n = vcount * ucount
Un = np.repeat(np.linspace(0, 1, ucount, endpoint=True), vcount)
Vn = np.tile(np.linspace(0, 1, vcount, endpoint=True), ucount)
U = umin + Un * (umax - umin)
V = vmin + Vn * (vmax - vmin)
vertices = np.zeros(n, dtype=vtype)
for i, (u, v) in enumerate(zip(U, V)):
vertices["position"][i] = func(u, v)
vertices["texcoord"][:, 0] = Un * urepeat
vertices["texcoord"][:, 1] = Vn * vrepeat
indices = []
for i in range(ucount - 1):
for j in range(vcount - 1):
indices.append(i * (vcount) + j)
indices.append(i * (vcount) + j + 1)
indices.append(i * (vcount) + j + vcount + 1)
indices.append(i * (vcount) + j + vcount)
indices.append(i * (vcount) + j + vcount + 1)
indices.append(i * (vcount) + j)
indices = np.array(indices, dtype=itype)
vertices["normal"] = normals(vertices["position"],
indices.reshape(len(indices) / 3, 3))
return vertices, indices
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