/// <summary>
/// Creates a new mesh where no vertices are shared.
/// </summary>
/// <param name="input">
/// The input mesh.
/// </param>
/// <returns>
/// A new mesh.
/// </returns>
public static MeshGeometry3D NoSharedVertices(this MeshGeometry3D input)
{
var p = new Point3DCollection();
var ti = new Int32Collection();
Vector3DCollection n = null;
if (input.Normals != null)
{
n = new Vector3DCollection();
}
PointCollection tc = null;
if (input.TextureCoordinates != null)
{
tc = new PointCollection();
}
for (int i = 0; i < input.TriangleIndices.Count; i += 3)
{
int i0 = i;
int i1 = i + 1;
int i2 = i + 2;
int index0 = input.TriangleIndices[i0];
int index1 = input.TriangleIndices[i1];
int index2 = input.TriangleIndices[i2];
var p0 = input.Positions[index0];
var p1 = input.Positions[index1];
var p2 = input.Positions[index2];
p.Add(p0);
p.Add(p1);
p.Add(p2);
ti.Add(i0);
ti.Add(i1);
ti.Add(i2);
if (n != null)
{
n.Add(input.Normals[index0]);
n.Add(input.Normals[index1]);
n.Add(input.Normals[index2]);
}
if (tc != null)
{
tc.Add(input.TextureCoordinates[index0]);
tc.Add(input.TextureCoordinates[index1]);
tc.Add(input.TextureCoordinates[index2]);
}
}
#if SHARPDX
return(new MeshGeometry3D {
Positions = p, TriangleIndices = new Core.IntCollection(ti), Normals = n, TextureCoordinates = tc
});
#else
return(new MeshGeometry3D {
Positions = p, TriangleIndices = ti, Normals = n, TextureCoordinates = tc
});
#endif
}
/// <summary>
/// Finds all edges in the mesh (each edge is only included once).
/// </summary>
/// <param name="mesh">
/// A mesh geometry.
/// </param>
/// <returns>
/// The edge indices (minimum index first).
/// </returns>
public static Int32Collection FindEdges(this MeshGeometry3D mesh)
{
var edges = new Int32Collection();
var dict = new HashSet <ulong>();
for (int i = 0; i < mesh.TriangleIndices.Count / 3; i++)
{
int i0 = i * 3;
for (int j = 0; j < 3; j++)
{
int index0 = mesh.TriangleIndices[i0 + j];
int index1 = mesh.TriangleIndices[i0 + ((j + 1) % 3)];
int minIndex = Math.Min(index0, index1);
int maxIndex = Math.Max(index1, index0);
ulong key = CreateKey((uint)minIndex, (uint)maxIndex);
if (!dict.Contains(key))
{
edges.Add(minIndex);
edges.Add(maxIndex);
dict.Add(key);
}
}
}
return(edges);
}
/// <summary>
///
/// </summary>
/// <returns></returns>
public MeshGeometry3D GetMesh()
{
var pos = new Point3DCollection(vertices.Select(x => new Point3D(x.p.X, x.p.Y, x.p.Z)));
var tris = new Int32Collection(triangles.Count * 3);
foreach (var tri in triangles)
{
tris.Add(tri.v[0]);
tris.Add(tri.v[1]);
tris.Add(tri.v[2]);
}
return(new MeshGeometry3D()
{
Positions = pos, TriangleIndices = tris
});
}
/// <summary>
/// Finds all edges where the angle between adjacent triangle normal vectors.
/// is larger than minimumAngle
/// </summary>
/// <param name="mesh">
/// A mesh geometry.
/// </param>
/// <param name="minimumAngle">
/// The minimum angle between the normal vectors of two adjacent triangles (degrees).
/// </param>
/// <returns>
/// The edge indices.
/// </returns>
public static Int32Collection FindSharpEdges(this MeshGeometry3D mesh, double minimumAngle)
{
var edgeIndices = new Int32Collection();
// the keys of the dictionary are created from the triangle indices of the edge
var edgeNormals = new Dictionary <ulong, Vector3D>();
for (int i = 0; i < mesh.TriangleIndices.Count / 3; i++)
{
int i0 = i * 3;
var p0 = mesh.Positions[mesh.TriangleIndices[i0]];
var p1 = mesh.Positions[mesh.TriangleIndices[i0 + 1]];
var p2 = mesh.Positions[mesh.TriangleIndices[i0 + 2]];
var p10 = p1 - p0;
var p20 = p2 - p0;
var n = SharedFunctions.CrossProduct(ref p10, ref p20);
n.Normalize();
for (int j = 0; j < 3; j++)
{
int index0 = mesh.TriangleIndices[i0 + j];
int index1 = mesh.TriangleIndices[i0 + ((j + 1) % 3)];
int minIndex = Math.Min(index0, index1);
int maxIndex = Math.Max(index0, index1);
ulong key = CreateKey((uint)minIndex, (uint)maxIndex);
Vector3D value;
if (edgeNormals.TryGetValue(key, out value))
{
var n2 = value;
n2.Normalize();
var angle = 180 / (DoubleOrSingle)Math.PI * (DoubleOrSingle)Math.Acos(SharedFunctions.DotProduct(ref n, ref n2));
if (angle > minimumAngle)
{
edgeIndices.Add(minIndex);
edgeIndices.Add(maxIndex);
}
}
else
{
edgeNormals.Add(key, n);
}
}
}
return(edgeIndices);
}
/// <summary>
/// Simplifies the specified mesh.
/// </summary>
/// <param name="mesh">
/// The mesh.
/// </param>
/// <param name="eps">
/// The tolerance.
/// </param>
/// <returns>
/// A simplified mesh.
/// </returns>
public static MeshGeometry3D Simplify(this MeshGeometry3D mesh, DoubleOrSingle eps)
{
// Find common positions
var dict = new Dictionary <int, int>(); // map position index to first occurence of same position
for (int i = 0; i < mesh.Positions.Count; i++)
{
for (int j = i + 1; j < mesh.Positions.Count; j++)
{
if (dict.ContainsKey(j))
{
continue;
}
var v = mesh.Positions[i] - mesh.Positions[j];
var l2 = SharedFunctions.LengthSquared(ref v);
if (l2 < eps)
{
dict.Add(j, i);
}
}
}
var p = new Point3DCollection();
var ti = new Int32Collection();
// create new positions array
var newIndex = new Dictionary <int, int>(); // map old index to new index
for (int i = 0; i < mesh.Positions.Count; i++)
{
if (!dict.ContainsKey(i))
{
newIndex.Add(i, p.Count);
p.Add(mesh.Positions[i]);
}
}
// Update triangle indices
foreach (int index in mesh.TriangleIndices)
{
int j;
ti.Add(dict.TryGetValue(index, out j) ? newIndex[j] : newIndex[index]);
}
#if SHARPDX
var result = new MeshGeometry3D {
Positions = p, TriangleIndices = new Core.IntCollection(ti),
};
#else
var result = new MeshGeometry3D {
Positions = p, TriangleIndices = ti
};
#endif
return(result);
}
/// <summary>
/// Finds edges that are only connected to one triangle.
/// </summary>
/// <param name="mesh">
/// A mesh geometry.
/// </param>
/// <returns>
/// The edge indices for the edges that are only used by one triangle.
/// </returns>
public static Int32Collection FindBorderEdges(this MeshGeometry3D mesh)
{
var dict = new Dictionary <ulong, int>();
for (int i = 0; i < mesh.TriangleIndices.Count / 3; i++)
{
int i0 = i * 3;
for (int j = 0; j < 3; j++)
{
int index0 = mesh.TriangleIndices[i0 + j];
int index1 = mesh.TriangleIndices[i0 + ((j + 1) % 3)];
int minIndex = Math.Min(index0, index1);
int maxIndex = Math.Max(index1, index0);
ulong key = CreateKey((uint)minIndex, (uint)maxIndex);
if (dict.ContainsKey(key))
{
dict[key] = dict[key] + 1;
}
else
{
dict.Add(key, 1);
}
}
}
var edges = new Int32Collection();
foreach (var kvp in dict)
{
// find edges only used by 1 triangle
if (kvp.Value == 1)
{
uint i0, i1;
ReverseKey(kvp.Key, out i0, out i1);
edges.Add((int)i0);
edges.Add((int)i1);
}
}
return(edges);
}