# -----------------------------------------------------------------------------
#
#  Gmsh Python extended tutorial 4
#
#  Post-processing data import: model-based
#
# -----------------------------------------------------------------------------

import gmsh
import sys

gmsh.initialize(sys.argv)

# Contrary to list-based view (see `x3.py'), model-based views are based on one
# or more meshes. Compared to list-based views, they are thus linked to one
# model (per step). Post-processing data stored in MSH files create such
# model-based views.

# Let's create a first model-based view using a simple mesh constructed by
# hand. We create a model with a discrete surface
gmsh.model.add("simple model")
surf = gmsh.model.addDiscreteEntity(2)

# We add 4 nodes and 2 3-node triangles (element type "2")
gmsh.model.mesh.addNodes(2, surf, [1, 2, 3, 4],
                         [0., 0., 0., 1., 0., 0., 1., 1., 0., 0., 1., 0.])
gmsh.model.mesh.addElementsByType(surf, 2, [1, 2], [1, 2, 3, 1, 3, 4])

# We can now create a new model-based view, to which we add 10 steps of
# node-based data:
t1 = gmsh.view.add("Continuous")
for step in range(0, 10):
    gmsh.view.addHomogeneousModelData(
        t1, step, "simple model", "NodeData",
        [1, 2, 3, 4],  # tags of nodes
        [10., 10., 12. + step, 13. + step])  # data, per node

# Besided node-based data, which result in continuous fields, one can also add
# general discontinous fields defined at the nodes of each element, using
# "ElementNodeData":
t2 = gmsh.view.add("Discontinuous")
for step in range(0, 10):
    gmsh.view.addHomogeneousModelData(
        t2, step, "simple model", "ElementNodeData",
        [1, 2],  # tags of elements
        [10., 10., 12. + step, 14., 15., 13. + step])  # data per element nodes

# Constant per element datasets can also be created using "ElementData". Note
# that a more general function `addModelData' to add data for hybrid meshes
# (when data is not homogeneous, i.e. when the number of nodes changes between
# elements) is also available.

# Each step of a model-based view can be defined on a different model, i.e. on a
# different mesh. Let's define a second model and mesh it
gmsh.model.add("another model")
gmsh.model.occ.addBox(0, 0, 0, 1, 1, 1)
gmsh.model.occ.synchronize()
gmsh.model.mesh.generate(3)

# We can add other steps to view "t" based on this new mesh:
nodes, coord, _ = gmsh.model.mesh.getNodes()
for step in range(11, 20):
    gmsh.view.addHomogeneousModelData(
        t1, step, "another model", "NodeData", nodes,
        [step * coord[i] for i in range(0, len(coord), 3)])

# This feature allows to create seamless animations for time-dependent datasets
# on deforming or remeshed models.

# High-order node-based datasets are supported without needing to supply the
# interpolation matrices (iso-parametric Lagrange elements). Arbitrary
# high-order datasets can be specified as "ElementNodeData", with the
# interpolation matrices specified in the same as as for list-based views (see
# `x3.py').

# Model-based views can be saved to disk using `gmsh.view.write()'; note that
# saving a view based on multiple meshes (like the view `t1') will automatically
# create several files. If the `PostProcessing.SaveMesh' option is not set,
# `gmsh.view.write()' will only save the view data, without the mesh (which
# could be saved independently with `gmsh.write()').
gmsh.view.write(t1, "x4_t1.msh")
gmsh.view.write(t2, "x4_t2.msh")

# Launch the GUI to see the results:
if '-nopopup' not in sys.argv:
    gmsh.fltk.run()

gmsh.finalize()