/// <summary>
/// Generates a structured mesh.
/// </summary>
/// <param name="bounds">Bounds of the mesh.</param>
/// <param name="nx">Number of segments in x direction.</param>
/// <param name="ny">Number of segments in y direction.</param>
/// <returns>Mesh</returns>
public static IMesh StructuredMesh(Rectangle bounds, int nx, int ny)
{
var polygon = new Polygon((nx + 1) * (ny + 1));
double x, y, dx, dy, left, bottom;
dx = bounds.Width / nx;
dy = bounds.Height / ny;
left = bounds.Left;
bottom = bounds.Bottom;
int i, j, k, l, n = 0;
// Add vertices.
var points = new Vertex[(nx + 1) * (ny + 1)];
for (i = 0; i <= nx; i++)
{
x = left + i * dx;
for (j = 0; j <= ny; j++)
{
y = bottom + j * dy;
points[n++] = new Vertex(x, y);
}
}
polygon.Points.AddRange(points);
n = 0;
// Set vertex hash and id.
foreach (var v in points)
{
v.hash = v.id = n++;
}
// Add boundary segments.
var segments = polygon.Segments;
segments.Capacity = 2 * (nx + ny);
Vertex a, b;
for (j = 0; j < ny; j++)
{
// Left
a = points[j];
b = points[j + 1];
segments.Add(new Segment(a, b, 1));
a.Label = b.Label = 1;
// Right
a = points[nx * (ny + 1) + j];
b = points[nx * (ny + 1) + (j + 1)];
segments.Add(new Segment(a, b, 1));
a.Label = b.Label = 1;
}
for (i = 0; i < nx; i++)
{
// Bottom
a = points[(ny + 1) * i];
b = points[(ny + 1) * (i + 1)];
segments.Add(new Segment(a, b, 1));
a.Label = b.Label = 1;
// Top
a = points[ny + (ny + 1) * i];
b = points[ny + (ny + 1) * (i + 1)];
segments.Add(new Segment(a, b, 1));
a.Label = b.Label = 1;
}
// Add triangles.
var triangles = new InputTriangle[2 * nx * ny];
n = 0;
for (i = 0; i < nx; i++)
{
for (j = 0; j < ny; j++)
{
k = j + (ny + 1) * i;
l = j + (ny + 1) * (i + 1);
// Create 2 triangles in rectangle [k, l, l + 1, k + 1].
if ((i + j) % 2 == 0)
{
// Diagonal from bottom left to top right.
triangles[n++] = new InputTriangle(k, l, l + 1);
triangles[n++] = new InputTriangle(k, l + 1, k + 1);
}
else
{
// Diagonal from top left to bottom right.
triangles[n++] = new InputTriangle(k, l, k + 1);
triangles[n++] = new InputTriangle(l, l + 1, k + 1);
}
}
}
return(Converter.ToMesh(polygon, triangles));
}
