渐进加密三角网滤波算法c++代码或者c++ 代码实现

渐进加密三角网滤波算法（Progressive Triangular Mesh Filtering）是一种用于图像压缩和降噪的算法，它通过对三角网格的逐层分解和滤波来实现。以下是一个简单的 C++ 实现：

#include <iostream>
#include <vector>
#include <cmath>

using namespace std;

struct Point {
    double x, y, z;
};

struct Triangle {
    int v1, v2, v3;
};

class TriangularMesh {
public:
    TriangularMesh(vector<Point>& vertices, vector<Triangle>& triangles) :
        vertices(vertices), triangles(triangles) {}
    void filter(double threshold) {
        for (int i = 0; i < vertices.size(); i++) {
            vertices[i].z = 0;
        }
        for (int i = 0; i < triangles.size(); i++) {
            Triangle& t = triangles[i];
            Point& v1 = vertices[t.v1];
            Point& v2 = vertices[t.v2];
            Point& v3 = vertices[t.v3];
            double area = computeArea(v1, v2, v3);
            if (area > threshold) {
                double z = (v1.z + v2.z + v3.z) / 3;
                v1.z += z;
                v2.z += z;
                v3.z += z;
            }
        }
        for (int i = 0; i < vertices.size(); i++) {
            int count = 0;
            double sum = 0;
            for (int j = 0; j < triangles.size(); j++) {
                Triangle& t = triangles[j];
                if (t.v1 == i || t.v2 == i || t.v3 == i) {
                    sum += (vertices[t.v1].z + vertices[t.v2].z + vertices[t.v3].z) / 3;
                    count++;
                }
            }
            vertices[i].z = sum / count;
        }
    }
private:
    vector<Point> vertices;
    vector<Triangle> triangles;
    double computeArea(Point& v1, Point& v2, Point& v3) {
        double a = sqrt(pow(v1.x - v2.x, 2) + pow(v1.y - v2.y, 2) + pow(v1.z - v2.z, 2));
        double b = sqrt(pow(v2.x - v3.x, 2) + pow(v2.y - v3.y, 2) + pow(v2.z - v3.z, 2));
        double c = sqrt(pow(v3.x - v1.x, 2) + pow(v3.y - v1.y, 2) + pow(v3.z - v1.z, 2));
        double s = (a + b + c) / 2;
        return sqrt(s * (s - a) * (s - b) * (s - c));
    }
};

int main() {
    vector<Point> vertices = {
        {0, 0, 1}, {0, 1, 0}, {1, 0, 0}, {0, -1, 0}, {-1, 0, 0}, {0, 0, -1}
    };
    vector<Triangle> triangles = {
        {0, 1, 2}, {0, 2, 3}, {0, 3, 4}, {0, 4, 1},
        {5, 2, 1}, {5, 3, 2}, {5, 4, 3}, {5, 1, 4}
    };
    TriangularMesh mesh(vertices, triangles);
    mesh.filter(0.1);
    for (int i = 0; i < vertices.size(); i++) {
        cout << vertices[i].x << " " << vertices[i].y << " " << vertices[i].z << endl;
    }
    return 0;
}

这段代码创建了一个包含 6 个顶点和 8 个三角形的三角网格，并对其进行了滤波。其中，`TriangularMesh` 类封装了顶点和三角形的数据，`filter` 方法实现了渐进加密三角网滤波算法。具体来说，它首先将所有顶点的高度值初始化为 0，然后遍历所有三角形，计算其面积，如果面积大于阈值，则将三个顶点的高度值设置为平均值。接着，它再遍历所有顶点，计算其周围所有三角形的平均高度值，并将该值设置为该顶点的高度值。最后，输出所有顶点的坐标和高度值。