def generate_sphere(name, radius, resolution):
"""
Generates a sphere with the provided resolution.
@type name: string
@param name: Name of this sphere.
@type radius: number
@param radius: Radius of sphere in kilometers.
@type resolution: number
@param resolution: Resolution of sphere (minimum 2)
@rtype: GeomNode
@return: A GeomNode with the given sphere.
"""
if resolution < 2:
raise ValueError, "resolution must be >= 2"
horizBands = resolution*2
vertBands = horizBands*2
vertexFormat = GeomVertexFormat.getV3n3c4t2()
vdata = GeomVertexData('%s_vdata' % name, vertexFormat, Geom.UHDynamic)
vertex = GeomVertexWriter(vdata, 'vertex')
color = GeomVertexWriter(vdata, 'color')
normal = GeomVertexWriter(vdata, 'normal')
texcoord = GeomVertexWriter(vdata, 'texcoord')
vertDelta = omath.TWOPI / vertBands
horizDelta = omath.TWOPI / horizBands
numVertices = 0
for i in range(vertBands+1):
lowTheta = i * vertDelta
highTheta = (i+1) * vertDelta
cosLowTheta = math.cos(lowTheta)
sinLowTheta = math.sin(lowTheta)
cosHighTheta = math.cos(highTheta)
sinHighTheta = math.sin(highTheta)
for j in range(horizBands):
horizTheta = j * horizDelta
cosHorizTheta = math.cos(horizTheta)
sinHorizTheta = math.sin(horizTheta)
ex = cosLowTheta*cosHorizTheta
ey = sinLowTheta
ez = cosLowTheta*sinHorizTheta
vertex.addData3f(ex*radius, ey*radius, ez*radius)
normal.addData3f(ex, ey, ez)
color.addData4f(.75, .75, .75, 1)
texcoord.addData2f(i / vertBands, j / horizBands)
ex = cosHighTheta*cosHorizTheta
ey = sinHighTheta
ez = cosHighTheta*sinHorizTheta
vertex.addData3f(ex*radius, ey*radius, ez*radius)
normal.addData3f(ex, ey, ez)
color.addData4f(.75, .75, .75, 1)
texcoord.addData2f(i / vertBands, j / horizBands)
numVertices += 2
prim = GeomTristrips(Geom.UHStatic)
prim.addConsecutiveVertices(0, numVertices)
prim.closePrimitive()
geom = Geom(vdata)
geom.addPrimitive(prim)
geomNode = GeomNode(name)
geomNode.addGeom(geom)
return GeomScaler(geomNode)
