public Box3Float GetBox3()
{
Box3Float box = new Box3Float();
for (int i = 0; i < this.Vertices.Count; i++)
{
box.UpdataRange(this.Vertices[i].X, this.Vertices[i].Y, this.Vertices[i].Z);
}
return(box);
}
public void ExecuteSimplification(float unitLength)
{
if (unitLength <= 1)
{
return;
}
Mesh newMesh = new Mesh(); //新建Mesh存放削减后的网格
Box3Float box = mesh.GetBox3(); //首先获取Mesh的空间范围 XYZ方向的最大最小值存在box中
int resx = (int)((box.Max3[0] - box.Min3[0]) / unitLength) + 1;
int resy = (int)((box.Max3[1] - box.Min3[1]) / unitLength) + 1;
int resz = (int)((box.Max3[2] - box.Min3[2]) / unitLength) + 1;
//在新的单位长度下，得出新空间划分出的每一维的长度
HashTable_Double2dArray <int> hash = new HashTable_Double2dArray <int>(resx + 1, resy + 1, resz + 1);
//创建hash表，这里使用的是双二维数组哈希表
for (int i = 0; i < mesh.Vertices.Count; i++)
{
Point3d p = mesh.Vertices[i];
int xindex = (int)((p.X - box.Min3[0]) / unitLength);
int yindex = (int)((p.Y - box.Min3[1]) / unitLength);
int zindex = (int)((p.Z - box.Min3[2]) / unitLength);
//计算点在新单位长度下的坐标
int value = 0;
bool hasValue = hash.GetHashValue(xindex, yindex, zindex, ref value);
if (!hasValue)
{
hash.SetHashValue(xindex, yindex, zindex, newMesh.Vertices.Count);
newMesh.AddVertex(new Point3d(xindex, yindex, zindex));
}//新单位长度下肯定有原来不同的点映射到相同的位置，
//总是添加第一次映射到这个位置的点入Mesh,之后的不再添加
}
for (int i = 0; i < mesh.Faces.Count; i++)
{
Triangle t = mesh.Faces[i];
Point3d p0 = mesh.Vertices[t.P0Index];
Point3d p1 = mesh.Vertices[t.P1Index];
Point3d p2 = mesh.Vertices[t.P2Index];
int xindex0 = (int)((p0.X - box.Min3[0]) / unitLength);
int yindex0 = (int)((p0.Y - box.Min3[1]) / unitLength);
int zindex0 = (int)((p0.Z - box.Min3[2]) / unitLength);
int index0 = 0;
hash.GetHashValue(xindex0, yindex0, zindex0, ref index0);
int xindex1 = (int)((p1.X - box.Min3[0]) / unitLength);
int yindex1 = (int)((p1.Y - box.Min3[1]) / unitLength);
int zindex1 = (int)((p1.Z - box.Min3[2]) / unitLength);
int index1 = 0;
hash.GetHashValue(xindex1, yindex1, zindex1, ref index1);
int xindex2 = (int)((p2.X - box.Min3[0]) / unitLength);
int yindex2 = (int)((p2.Y - box.Min3[1]) / unitLength);
int zindex2 = (int)((p2.Z - box.Min3[2]) / unitLength);
int index2 = 0;
hash.GetHashValue(xindex2, yindex2, zindex2, ref index2);
if (!(index0 == index1 || index0 == index2 || index1 == index2))
{
newMesh.AddFace(new Triangle(index0, index1, index2));
}
//对于每个三角形，找出其三点对应的新位置，检查是否有两个点重合（退化），
//添加不退化的三角形
}
for (int i = 0; i < newMesh.Vertices.Count; i++)
{
Point3d p = newMesh.Vertices[i];
p.X = (float)(unitLength * p.X + box.Min3[0]);
p.Y = (float)(unitLength * p.Y + box.Min3[1]);
p.Z = (float)(unitLength * p.Z + box.Min3[2]);
}//将新Mesh的坐标放大到和原来一样的尺度
mesh.Clear();
mesh.Vertices = newMesh.Vertices;
mesh.Faces = newMesh.Faces;
//替换旧Mesh的数据
}