qt triangle三角划分

Qt中可以使用QPolygonF类来表示多边形，包括三角形。要进行三角划分，可以使用第三方库，比如Triangle或者Poly2Tri。这些库都可以生成多边形的三角剖分，其中包括三角形。

使用Triangle库进行三角划分的步骤如下：

1. 安装Triangle库，并将其包含到Qt项目中。

2. 构建一个QPolygonF对象，表示要进行三角划分的多边形。

3. 将QPolygonF对象转换为Triangle库所需的结构体格式，使用triangulate()函数进行三角划分。

4. 将三角形数据转换为QPolygonF对象，用于绘制。

下面是一个示例代码，演示如何使用Triangle库进行三角划分并绘制三角形：

#include <QPolygonF>
#include <iostream>
#include "triangle.h"

int main(int argc, char *argv[])
{
    // 构建一个QPolygonF对象，表示多边形
    QPolygonF poly;
    poly << QPointF(0, 0) << QPointF(100, 0) << QPointF(100, 100) << QPointF(0, 100);

    // 将多边形转换为Triangle库所需的结构体格式
    int numPoints = poly.size();
    double* pointList = new double[numPoints * 2];
    for (int i = 0; i < numPoints; i++) {
        pointList[i * 2] = poly[i].x();
        pointList[i * 2 + 1] = poly[i].y();
    }

    // 进行三角划分
    triangulateio in, out;
    in.numberofpoints = numPoints;
    in.numberofpointattributes = 0;
    in.pointlist = pointList;
    in.pointmarkerlist = nullptr;
    in.numberofsegments = 0;
    in.segmentlist = nullptr;
    in.segmentmarkerlist = nullptr;
    in.numberofholes = 0;
    in.numberoftriangles = 0;
    in.trianglelist = nullptr;
    in.triangleattributelist = nullptr;
    in.trianglearealist = nullptr;
    in.neighborlist = nullptr;
    in.numberoftriangleattributes = 0;
    out.pointlist = nullptr;
    out.pointmarkerlist = nullptr;
    out.trianglelist = nullptr;
    out.triangleattributelist = nullptr;
    out.neighborlist = nullptr;
    out.segmentlist = nullptr;
    out.segmentmarkerlist = nullptr;
    out.edgelist = nullptr;
    out.edgemarkerlist = nullptr;
    out.normlist = nullptr;
    out.numberofpoints = 0;
    out.numberofpointattributes = 0;
    out.numberoftriangles = 0;
    out.numberofcorners = 0;
    out.numberoftriangleattributes = 0;
    out.numberofsegments = 0;
    out.numberofedges = 0;
    char options[] = "p";
    triangulate(options, &in, &out, nullptr);

    // 将三角形数据转换为QPolygonF对象，用于绘制
    QPolygonF triangles;
    for (int i = 0; i < out.numberoftriangles; i++) {
        double* point1 = &out.pointlist[out.trianglelist[i * 3] * 2];
        double* point2 = &out.pointlist[out.trianglelist[i * 3 + 1] * 2];
        double* point3 = &out.pointlist[out.trianglelist[i * 3 + 2] * 2];
        triangles << QPointF(point1[0], point1[1]) << QPointF(point2[0], point2[1]) << QPointF(point3[0], point3[1]);
    }

    // 输出三角形数量
    std::cout << "Number of triangles: " << out.numberoftriangles << std::endl;

    // 释放内存
    delete[] pointList;
    free(in.pointlist);
    free(in.pointmarkerlist);
    free(out.pointlist);
    free(out.pointmarkerlist);
    free(out.trianglelist);
    free(out.triangleattributelist);
    free(out.neighborlist);
    free(out.segmentlist);
    free(out.segmentmarkerlist);
    free(out.edgelist);
    free(out.edgemarkerlist);
    free(out.normlist);

    return 0;
}

这段代码将多边形划分为三角形，并将三角形存储在QPolygonF对象triangles中。可以使用Qt的painter对象来绘制这些三角形。