/// <summary>
/// Generate a HalfEdgeMesh from an existing MeshGeometry3D Object.
/// </summary>
/// <param name="meshGeometry">The existing MeshGeometry3D Object.</param>
/// <param name="calculateNormals">Calculate Vertex Normals or not.</param>
/// <returns>The generated HalfEdgeMesh.</returns>
public static HalfEdgeMesh GenerateFromMeshGeometry3D(MeshGeometry3D meshGeometry, bool calculateNormals = false)
{
var vertices = meshGeometry.Positions.Select(p => new Vertex((float)p.X, (float)p.Y, (float)p.Z)).ToList();
var triangles = new List <Triangle>();
for (int i = 0; i < meshGeometry.TriangleIndices.Count; i += 3)
{
triangles.Add(new Triangle(meshGeometry.TriangleIndices.ElementAt(i),
meshGeometry.TriangleIndices.ElementAt(i + 1),
meshGeometry.TriangleIndices.ElementAt(i + 2)));
}
var mesh = new HalfEdgeMesh();
mesh.AddVertices(vertices);
mesh.AddTriangles(triangles);
if (calculateNormals)
{
mesh.CalculateVertexNormals();
}
return(mesh);
}
/// <summary>
/// Generate a HalfEdgeMesh of a Sphere.
/// </summary>
/// <param name="center">The Center of the Sphere.</param>
/// <param name="radius">The Radius of the Sphere.</param>
/// <param name="numSides">Number of Sides of the Sphere (multiply by 4 for one Ring).</param>
/// <param name="sides">Which Sides of the Sphere should be generated.</param>
/// <param name="calculateNormals">Calculate Vertex Normals or not.</param>
/// <returns>The generated HalfEdgeMesh.</returns>
public static HalfEdgeMesh GenerateSphere(Vector center,
float radius = 1, int numSides = 8, CubeSides sides = CubeSides.All, bool calculateNormals = false)
{
var shiftVector = Vector.One * 0.5f;
var mesh = new HalfEdgeMesh();
var sideLength = 1f / numSides;
var verticesPerSide = numSides + 1;
var vertices = new List <Vertex>();
var bottomVertices = new List <Vertex>(verticesPerSide * verticesPerSide);
var topVertices = new List <Vertex>(verticesPerSide * verticesPerSide);
var frontVertices = new List <Vertex>(verticesPerSide * verticesPerSide);
var backVertices = new List <Vertex>(verticesPerSide * verticesPerSide);
var leftVertices = new List <Vertex>(verticesPerSide * verticesPerSide);
var rightVertices = new List <Vertex>(verticesPerSide * verticesPerSide);
var idx = 0;
for (int z = 0; z <= numSides; z++)
{
for (int y = 0; y <= numSides; y++)
{
for (int x = 0; x <= numSides; x++)
{
if (z == 0 || z == numSides || x == 0 || x == numSides || y == 0 || y == numSides)
{
var vertex = new Vertex(x * sideLength - 0.5f, y * sideLength - 0.5f, z * sideLength - 0.5f)
{
Index = idx,
};
if (x == 0 && sides.HasFlag(CubeSides.NegativeZ))
{
bottomVertices.Add(vertex);
}
else if (x == numSides && sides.HasFlag(CubeSides.PositiveZ))
{
topVertices.Add(vertex);
}
if (y == 0 && sides.HasFlag(CubeSides.NegativeY))
{
frontVertices.Add(vertex);
}
else if (y == numSides && sides.HasFlag(CubeSides.PositiveY))
{
backVertices.Add(vertex);
}
if (z == 0 && sides.HasFlag(CubeSides.NegativeX))
{
leftVertices.Add(vertex);
}
else if (z == numSides && sides.HasFlag(CubeSides.PositiveX))
{
rightVertices.Add(vertex);
}
vertices.Add(vertex);
idx++;
}
else
{
x += numSides - 2;
}
}
}
}
foreach (var vertex in vertices)
{
var vertexVector = (Vector)vertex;
vertexVector.Normalize();
vertex.Position = vertexVector * radius + center;
}
mesh.AddVertices(vertices);
var triangles = new List <Triangle>();
for (int i = 0; i < numSides * numSides; i++)
{
idx = i + i / numSides;
var nextIdx = idx + 1;
var nextRowIdx = nextIdx + numSides;
var nextRowNextIdx = nextRowIdx + 1;
if (sides.HasFlag(CubeSides.NegativeZ))
{
mesh.AddTriangle(new Triangle(bottomVertices[idx].Index, bottomVertices[nextRowNextIdx].Index, bottomVertices[nextIdx].Index));
mesh.AddTriangle(new Triangle(bottomVertices[idx].Index, bottomVertices[nextRowIdx].Index, bottomVertices[nextRowNextIdx].Index));
}
if (sides.HasFlag(CubeSides.PositiveZ))
{
mesh.AddTriangle(new Triangle(topVertices[idx].Index, topVertices[nextIdx].Index, topVertices[nextRowNextIdx].Index));
mesh.AddTriangle(new Triangle(topVertices[idx].Index, topVertices[nextRowNextIdx].Index, topVertices[nextRowIdx].Index));
}
if (sides.HasFlag(CubeSides.NegativeY))
{
mesh.AddTriangle(new Triangle(frontVertices[idx].Index, frontVertices[nextIdx].Index, frontVertices[nextRowNextIdx].Index));
mesh.AddTriangle(new Triangle(frontVertices[idx].Index, frontVertices[nextRowNextIdx].Index, frontVertices[nextRowIdx].Index));
}
if (sides.HasFlag(CubeSides.PositiveY))
{
mesh.AddTriangle(new Triangle(backVertices[idx].Index, backVertices[nextRowNextIdx].Index, backVertices[nextIdx].Index));
mesh.AddTriangle(new Triangle(backVertices[idx].Index, backVertices[nextRowIdx].Index, backVertices[nextRowNextIdx].Index));
}
if (sides.HasFlag(CubeSides.NegativeX))
{
mesh.AddTriangle(new Triangle(leftVertices[idx].Index, leftVertices[nextRowNextIdx].Index, leftVertices[nextIdx].Index));
mesh.AddTriangle(new Triangle(leftVertices[idx].Index, leftVertices[nextRowIdx].Index, leftVertices[nextRowNextIdx].Index));
}
if (sides.HasFlag(CubeSides.PositiveX))
{
mesh.AddTriangle(new Triangle(rightVertices[idx].Index, rightVertices[nextIdx].Index, rightVertices[nextRowNextIdx].Index));
mesh.AddTriangle(new Triangle(rightVertices[idx].Index, rightVertices[nextRowNextIdx].Index, rightVertices[nextRowIdx].Index));
}
}
if (calculateNormals)
{
mesh.CalculateVertexNormals();
}
return(mesh);
}