"""
An example creating a structured grid data set from numpy arrays using TVTK 
and visualizing it using mlab.

In this example, we create a structured-grid data set: we describe
data, both scalar and vector, lying on a structured-grid, ie a grid where
each vertex has 6 neighboors. For this we directly create a
StructuredGrid tvtk object, rather than using the mlab.pipeline source
functions, as it gives us more control. 

To visualize the resulting dataset, we apply several modules, using the
mlab.pipeline interface (see :ref:`controlling-the-pipeline-with-mlab-scripts`)
"""
# Author: Prabhu Ramachandran <prabhu@aero.iitb.ac.in>
# Copyright (c) 2008, Prabhu Ramachandran.
# License: BSD Style.

from numpy import mgrid, empty, sin, pi
from enthought.tvtk.api import tvtk
from enthought.mayavi import mlab

# Generate some points.
x, y, z = mgrid[1:6:11j,0:4:13j,0:3:6j]
base = x[...,0] + y[...,0]
# Some interesting z values.
for i in range(z.shape[2]):
    z[...,i] = base*0.25*i

# The actual points.
pts = empty(z.shape + (3,), dtype=float)
pts[...,0] = x
pts[...,1] = y
pts[...,2] = z

# Simple scalars.
scalars = x*x + y*y + z*z
# Some vectors
vectors = empty(z.shape + (3,), dtype=float)
vectors[...,0] = (4 - y*2)
vectors[...,1] = (x*3 - 12)
vectors[...,2] = sin(z*pi)

# We reorder the points, scalars and vectors so this is as per VTK's
# requirement of x first, y next and z last.
pts = pts.transpose(2, 1, 0, 3).copy()
pts.shape = pts.size/3, 3
scalars = scalars.T.copy()
vectors = vectors.transpose(2, 1, 0, 3).copy()
vectors.shape = vectors.size/3, 3

# Create the dataset.
sg = tvtk.StructuredGrid(dimensions=x.shape, points=pts)
sg.point_data.scalars = scalars.ravel()
sg.point_data.scalars.name = 'temperature'
sg.point_data.vectors = vectors
sg.point_data.vectors.name = 'velocity'

# Thats it!

# Now visualize the data.
d = mlab.pipeline.add_dataset(sg)
gx = mlab.pipeline.grid_plane(d)
gy = mlab.pipeline.grid_plane(d)
gy.grid_plane.axis = 'y'
gz = mlab.pipeline.grid_plane(d)
gz.grid_plane.axis = 'z'
iso = mlab.pipeline.iso_surface(d)
iso.contour.maximum_contour = 75.0
vec = mlab.pipeline.vectors(d)
vec.glyph.mask_input_points = True
vec.glyph.glyph.scale_factor = 1.5

mlab.show()