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import math
import numpy
import moderngl as mlg
from moderngl_window.opengl.vao import VAO
from moderngl_window.geometry import AttributeNames
def sphere(
radius=0.5,
sectors=32,
rings=16,
normals=True,
uvs=True,
name: str = None,
attr_names=AttributeNames,
) -> VAO:
"""Creates a sphere.
Keyword Args:
radius (float): Radius or the sphere
rings (int): number or horizontal rings
sectors (int): number of vertical segments
normals (bool): Include normals in the VAO
uvs (bool): Include texture coordinates in the VAO
name (str): An optional name for the VAO
attr_names (AttributeNames): Attribute names
Returns:
A :py:class:`VAO` instance
"""
R = 1.0 / (rings - 1)
S = 1.0 / (sectors - 1)
vertices = [0] * (rings * sectors * 3)
normals = [0] * (rings * sectors * 3)
uvs = [0] * (rings * sectors * 2)
v, n, t = 0, 0, 0
for r in range(rings):
for s in range(sectors):
y = math.sin(-math.pi / 2 + math.pi * r * R)
x = math.cos(2 * math.pi * s * S) * math.sin(math.pi * r * R)
z = math.sin(2 * math.pi * s * S) * math.sin(math.pi * r * R)
uvs[t] = s * S
uvs[t + 1] = r * R
vertices[v] = x * radius
vertices[v + 1] = y * radius
vertices[v + 2] = z * radius
normals[n] = x
normals[n + 1] = y
normals[n + 2] = z
t += 2
v += 3
n += 3
indices = [0] * rings * sectors * 6
i = 0
for r in range(rings - 1):
for s in range(sectors - 1):
indices[i] = r * sectors + s
indices[i + 1] = (r + 1) * sectors + (s + 1)
indices[i + 2] = r * sectors + (s + 1)
indices[i + 3] = r * sectors + s
indices[i + 4] = (r + 1) * sectors + s
indices[i + 5] = (r + 1) * sectors + (s + 1)
i += 6
vao = VAO(name or "sphere", mode=mlg.TRIANGLES)
vbo_vertices = numpy.array(vertices, dtype=numpy.float32)
vao.buffer(vbo_vertices, "3f", [attr_names.POSITION])
if normals:
vbo_normals = numpy.array(normals, dtype=numpy.float32)
vao.buffer(vbo_normals, "3f", [attr_names.NORMAL])
if uvs:
vbo_uvs = numpy.array(uvs, dtype=numpy.float32)
vao.buffer(vbo_uvs, "2f", [attr_names.TEXCOORD_0])
vbo_elements = numpy.array(indices, dtype=numpy.uint32)
vao.index_buffer(vbo_elements, index_element_size=4)
return vao
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