// get normal direction of a triangle
public Vector3D GetTriangleNormal(int n)
{
Triangle3D tri = GetTriangle(n);
Point3D pt0 = GetPoint(tri.n0);
Point3D pt1 = GetPoint(tri.n1);
Point3D pt2 = GetPoint(tri.n2);
double dx1 = pt1.X - pt0.X;
double dy1 = pt1.Y - pt0.Y;
double dz1 = pt1.Z - pt0.Z;
double dx2 = pt2.X - pt0.X;
double dy2 = pt2.Y - pt0.Y;
double dz2 = pt2.Z - pt0.Z;
double vx = dy1 * dz2 - dz1 * dy2;
double vy = dz1 * dx2 - dx1 * dz2;
double vz = dx1 * dy2 - dy1 * dx2;
double length = Math.Sqrt(vx * vx + vy * vy + vz * vz);
return(new Vector3D(vx / length, vy / length, vz / length));
}
// set a triangle in this mesh
public void SetTriangle(int n, Triangle3D triangle)
{
m_tris[n] = triangle;
}
public void SetTriangle(int i, int m0, int m1, int m2)
{
m_tris[i] = new Triangle3D(m0, m1, m2);
}
// set this ModelVisual3D object from a array of mesh3D objects
private void SetModel(ArrayList meshs, Material backMaterial)
{
int nMeshNo = meshs.Count;
if (nMeshNo == 0)
{
return;
}
MeshGeometry3D triangleMesh = new MeshGeometry3D();
int nTotalVertNo = 0;
for (int j = 0; j < nMeshNo; j++)
{
Mesh3D mesh = (Mesh3D)meshs[j];
int nVertNo = mesh.GetVertexNo();
int nTriNo = mesh.GetTriangleNo();
if ((nVertNo <= 0) || (nTriNo <= 0))
{
continue;
}
double[] vx = new double[nVertNo];
double[] vy = new double[nVertNo];
double[] vz = new double[nVertNo];
for (int i = 0; i < nVertNo; i++)
{
vx[i] = vy[i] = vz[i] = 0;
}
// get normal of each vertex
for (int i = 0; i < nTriNo; i++)
{
Triangle3D tri = mesh.GetTriangle(i);
Vector3D vN = mesh.GetTriangleNormal(i);
int n0 = tri.n0;
int n1 = tri.n1;
int n2 = tri.n2;
vx[n0] += vN.X;
vy[n0] += vN.Y;
vz[n0] += vN.Z;
vx[n1] += vN.X;
vy[n1] += vN.Y;
vz[n1] += vN.Z;
vx[n2] += vN.X;
vy[n2] += vN.Y;
vz[n2] += vN.Z;
}
for (int i = 0; i < nVertNo; i++)
{
double length = Math.Sqrt(vx[i] * vx[i] + vy[i] * vy[i] + vz[i] * vz[i]);
if (length > 1e-20)
{
vx[i] /= length;
vy[i] /= length;
vz[i] /= length;
}
triangleMesh.Positions.Add(mesh.GetPoint(i));
Color color = mesh.GetColor(i);
Point mapPt = m_mapping.GetMappingPosition(color);
triangleMesh.TextureCoordinates.Add(new System.Windows.Point(mapPt.X, mapPt.Y));
triangleMesh.Normals.Add(new Vector3D(vx[i], vy[i], vz[i]));
}
for (int i = 0; i < nTriNo; i++)
{
Triangle3D tri = mesh.GetTriangle(i);
int n0 = tri.n0;
int n1 = tri.n1;
int n2 = tri.n2;
triangleMesh.TriangleIndices.Add(nTotalVertNo + n0);
triangleMesh.TriangleIndices.Add(nTotalVertNo + n1);
triangleMesh.TriangleIndices.Add(nTotalVertNo + n2);
}
nTotalVertNo += nVertNo;
}
//Material material = new DiffuseMaterial(new SolidColorBrush(Colors.Red));
Material material = m_mapping.m_material;
GeometryModel3D triangleModel = new GeometryModel3D(triangleMesh, material);
triangleModel.Transform = new Transform3DGroup();
if (backMaterial != null)
{
triangleModel.BackMaterial = backMaterial;
}
Content = triangleModel;
}