private static (Mesh Mesh, double MaxElevation, double MinElevation) GenerateMesh(
double[] elevations,
Vector3 origin,
int rowWidth,
double cellWidth,
double cellHeight)
{
var minElevation = double.MaxValue;
var maxElevation = double.MinValue;
var mesh = new Mesh();
var triangles = (Math.Sqrt(elevations.Length) - 1) * rowWidth * 2;
for (var y = 0; y < rowWidth; y++)
{
for (var x = 0; x < rowWidth; x++)
{
var ei = x + y * rowWidth;
var el = elevations[ei];
minElevation = Math.Min(minElevation, el);
maxElevation = Math.Max(maxElevation, el);
var u = (double)x / (double)(rowWidth - 1);
var v = (double)y / (double)(rowWidth - 1);
// Shrink the UV space slightly to avoid
// visible edges on applied textures.
var uvTol = 0.001;
u = u == 0.0 ? uvTol : u;
v = v == 0.0 ? uvTol : v;
u = u == 1.0 ? 1 - uvTol : u;
v = v == 1.0 ? 1 - uvTol : v;
var uv = new UV(u, v);
mesh.AddVertex(origin + new Vector3(x * cellWidth, y * cellHeight, el), uv: uv);
if (y > 0 && x > 0)
{
var i = x + y * rowWidth;
// Top triangle
var a = mesh.Vertices[i];
var b = mesh.Vertices[i - 1];
var c = mesh.Vertices[i - rowWidth];
var tt = mesh.AddTriangle(a, b, c);
// Bottom triangle
var d = mesh.Vertices[i - 1];
var e = mesh.Vertices[i - 1 - rowWidth];
var f = mesh.Vertices[i - rowWidth];
var tb = mesh.AddTriangle(d, e, f);
}
}
}
mesh.ComputeNormals();
return(mesh, maxElevation, minElevation);
}
/// <summary>
/// Create a topography from a custom mesh. It is assumed that the mesh is an open mesh that's roughly parallel to the XY plane.
/// </summary>
/// <param name="mesh">The mesh geometry of the topography.</param>
/// <param name="material">The topography's material.</param>
/// <param name="transform">The topography's transform.</param>
/// <param name="id">The topography's id.</param>
/// <param name="name">The topography's name.</param>
/// <returns></returns>
public Topography(Mesh mesh, Material material, Transform transform, Guid id, string name) : base(material,
transform,
false,
id,
name)
{
var newMesh = new Mesh(mesh);
var bbox = new BBox3(mesh.Vertices.Select(v => v.Position));
this._minElevation = bbox.Min.Z;
this._maxElevation = bbox.Max.Z;
double absoluteMinimumElevation = this.AbsoluteMinimumElevation ?? this.MinElevation - this.DepthBelowMinimumElevation;
var nakedBoundaries = mesh.GetNakedBoundaries();
var basePlane = new Plane((0, 0, absoluteMinimumElevation), (0, 0, 1));
foreach (var polygon in nakedBoundaries)
{
// construct bottom
var bottomPolygon = polygon.Project(basePlane);
var tess = new Tess
{
NoEmptyPolygons = true
};
tess.AddContour(bottomPolygon.Reversed().ToContourVertexArray());
tess.Tessellate(WindingRule.Positive, ElementType.Polygons, 3);
var faceMesh = tess.ToMesh(normal: (0, 0, -1));
this._baseVerts = new List <Vertex>(faceMesh.Vertices);
newMesh.AddMesh(faceMesh);
// construct sides
var upperSegments = polygon.Segments();
var lowerSegments = bottomPolygon.Segments();
for (int i = 0; i < upperSegments.Count(); i++)
{
var topEdge = upperSegments[i];
var bottomEdge = lowerSegments[i];
var normal = topEdge.Direction().Cross(Vector3.ZAxis).Unitized();
var a = newMesh.AddVertex(topEdge.Start, normal: normal);
var b = newMesh.AddVertex(topEdge.End, normal: normal);
var c = newMesh.AddVertex(bottomEdge.End, normal: normal);
var d = newMesh.AddVertex(bottomEdge.Start, normal: normal);
newMesh.AddTriangle(a, c, b);
newMesh.AddTriangle(a, d, c);
}
}
this.Mesh = newMesh;
}
private void CreateSidesAndBottomMesh(Mesh mesh,
int rowWidth,
double depth,
double cellHeight,
double cellWidth,
Vector3 origin)
{
// Track the last created "low"
// point so that we can merge
// vertices in the side meshes.
Vertex lastL = null;
Vertex lastR = null;
Vertex lastT = null;
Vertex lastB = null;
(Vector3 U, Vector3 V)basisLeft = (default(Vector3), default(Vector3));
(Vector3 U, Vector3 V)basisRight = (default(Vector3), default(Vector3));
(Vector3 U, Vector3 V)basisTop = (default(Vector3), default(Vector3));
(Vector3 U, Vector3 V)basisBottom = (default(Vector3), default(Vector3));
this._baseVerts.Clear();
for (var u = 0; u < rowWidth - 1; u++)
{
if (u == 0)
{
basisLeft = Vector3.XAxis.Negate().ComputeDefaultBasisVectors();
basisRight = Vector3.XAxis.ComputeDefaultBasisVectors();
basisTop = Vector3.YAxis.ComputeDefaultBasisVectors();
basisBottom = Vector3.YAxis.Negate().ComputeDefaultBasisVectors();
}
// Left side
Vertex l1 = null;
var i1 = u * rowWidth;
var v1Existing = mesh.Vertices[i1];
var v1 = mesh.AddVertex(v1Existing.Position, normal: Vector3.XAxis.Negate());
if (lastL != null)
{
l1 = lastL;
}
else
{
var p = new Vector3(v1.Position.X, v1.Position.Y, depth);
l1 = mesh.AddVertex(p);
_baseVerts.Add(l1);
}
var i2 = i1 + rowWidth;
var v2Existing = mesh.Vertices[i2];
var v2 = mesh.AddVertex(v2Existing.Position);
var pl2 = new Vector3(v2.Position.X, v2.Position.Y, depth);
var l2 = mesh.AddVertex(pl2);
_baseVerts.Add(l2);
lastL = l2;
mesh.AddTriangle(l1, v1, v2);
mesh.AddTriangle(l2, l1, v2);
// Right side
Vertex l3 = null;
var i3 = u * (rowWidth) + (rowWidth - 1);
var v3Existing = mesh.Vertices[i3];
var v3 = mesh.AddVertex(v3Existing.Position, normal: Vector3.XAxis);
if (lastR != null)
{
l3 = lastR;
}
else
{
var p = new Vector3(v3.Position.X, v3.Position.Y, depth);
l3 = mesh.AddVertex(p);
_baseVerts.Add(l3);
}
var i4 = i3 + rowWidth;
var v4Existing = mesh.Vertices[i4];
var v4 = mesh.AddVertex(v4Existing.Position);
var pl4 = new Vector3(v4.Position.X, v4.Position.Y, depth);
var l4 = mesh.AddVertex(pl4);
_baseVerts.Add(l4);
lastR = l4;
mesh.AddTriangle(l3, v4, v3);
mesh.AddTriangle(l3, l4, v4);
// Top side
Vertex l5 = null;
var i5 = u;
var v5Existing = mesh.Vertices[i5];
var v5 = mesh.AddVertex(v5Existing.Position, normal: Vector3.YAxis);
if (lastT != null)
{
l5 = lastT;
}
else
{
var p = new Vector3(v5.Position.X, v5.Position.Y, depth);
l5 = mesh.AddVertex(p);
_baseVerts.Add(l5);
}
var i6 = i5 + 1;
var v6Existing = mesh.Vertices[i6];
var v6 = mesh.AddVertex(v6Existing.Position);
var pl6 = new Vector3(v6.Position.X, v6.Position.Y, depth);
var l6 = mesh.AddVertex(pl6);
_baseVerts.Add(l6);
lastT = l6;
mesh.AddTriangle(l5, v6, v5);
mesh.AddTriangle(l5, l6, v6);
// Bottom side
Vertex l7 = null;
var i7 = rowWidth * rowWidth - u - 1;
var v7Existing = mesh.Vertices[i7];
var v7 = mesh.AddVertex(v7Existing.Position, normal: Vector3.YAxis.Negate());
if (lastB != null)
{
l7 = lastB;
}
else
{
var p = new Vector3(v7.Position.X, v7.Position.Y, depth);
l7 = mesh.AddVertex(p);
_baseVerts.Add(l7);
}
var i8 = i7 - 1;
var v8Existing = mesh.Vertices[i8];
var v8 = mesh.AddVertex(v8Existing.Position);
var pl8 = new Vector3(v8.Position.X, v8.Position.Y, depth);
var l8 = mesh.AddVertex(pl8);
_baseVerts.Add(l8);
lastB = l8;
mesh.AddTriangle(l7, v8, v7);
mesh.AddTriangle(l7, l8, v8);
}
// Add the bottom
var bb1 = mesh.AddVertex(origin + new Vector3(0, 0, depth));
var bb2 = mesh.AddVertex(origin + new Vector3((rowWidth - 1) * cellWidth, 0, depth));
var bb3 = mesh.AddVertex(origin + new Vector3((rowWidth - 1) * cellWidth, (rowWidth - 1) * cellHeight, depth));
var bb4 = mesh.AddVertex(origin + new Vector3(0, (rowWidth - 1) * cellHeight, depth));
_baseVerts.AddRange(new[] { bb1, bb2, bb3, bb4 });
mesh.AddTriangle(bb1, bb3, bb2);
mesh.AddTriangle(bb1, bb4, bb3);
mesh.ComputeNormals();
}