def two_triangles():
"""
Returns a simple triangular grid: 4 nodes, two triangles, five edges.
"""
nodes = [(0.1, 0.1), (2.1, 0.1), (1.1, 2.1), (3.1, 2.1)]
faces = [
(0, 1, 2),
(1, 3, 2),
]
edges = [(0, 1), (1, 3), (3, 2), (2, 0), (1, 2)]
return ugrid.UGrid(nodes, faces, edges)
def two_triangles():
"""
returns about the simplest triangle grid possible
4 nodes, two triangles, five edges
"""
nodes = [(0.1, 0.1), (2.1, 0.1), (1.1, 2.1), (3.1, 2.1)]
faces = [
(0, 1, 2),
(1, 3, 2),
]
edges = [(0, 1), (1, 3), (3, 2), (2, 0), (1, 2)]
return ugrid.UGrid(nodes, faces, edges)
def twenty_one_triangles():
"""
Returns a basic triangular grid: 21 triangles, a hole, and a tail.
"""
nodes = [
(5, 1),
(10, 1),
(3, 3),
(7, 3),
(9, 4),
(12, 4),
(5, 5),
(3, 7),
(5, 7),
(7, 7),
(9, 7),
(11, 7),
(5, 9),
(8, 9),
(11, 9),
(9, 11),
(11, 11),
(7, 13),
(9, 13),
(7, 15),
]
faces = [
(0, 1, 3),
(0, 6, 2),
(0, 3, 6),
(1, 4, 3),
(1, 5, 4),
(2, 6, 7),
(6, 8, 7),
(7, 8, 12),
(6, 9, 8),
(8, 9, 12),
(9, 13, 12),
(4, 5, 11),
(4, 11, 10),
(9, 10, 13),
(10, 11, 14),
(10, 14, 13),
(13, 14, 15),
(14, 16, 15),
(15, 16, 18),
(15, 18, 17),
(17, 18, 19),
]
# We may want to use this later to define just the outer boundary.
boundaries = [
(0, 1),
(1, 5),
(5, 11),
(11, 14),
(14, 16),
(16, 18),
(18, 19),
(19, 17),
(17, 15),
(15, 13),
(13, 12),
(12, 7),
(7, 2),
(2, 0),
(3, 4),
(4, 10),
(10, 9),
(9, 6),
(6, 3),
]
grid = ugrid.UGrid(nodes, faces, boundaries=boundaries)
grid.build_edges()
return grid