qt 复杂多边形的三角剖分

在Qt中，可以使用QPolygonF类来表示一个多边形，包括复杂多边形。要对复杂多边形进行三角剖分，可以使用第三方库，如Triangle库。

以下是一个使用Triangle库进行复杂多边形三角剖分的示例代码：

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

QVector<QPolygonF> triangulate(QPolygonF polygon)
{
    QVector<QPolygonF> triangles;

    // Convert QPolygonF to triangulateio structure
    triangulateio in, out;
    in.numberofpoints = polygon.size();
    in.pointlist = (REAL*)malloc(in.numberofpoints * 2 * sizeof(REAL));
    for (int i = 0; i < polygon.size(); i++) {
        in.pointlist[2 * i] = polygon[i].x();
        in.pointlist[2 * i + 1] = polygon[i].y();
    }
    in.numberofpointattributes = 0;
    in.pointattributelist = NULL;
    in.pointmarkerlist = NULL;
    in.numberofsegments = polygon.size();
    in.segmentlist = (int*)malloc(in.numberofsegments * 2 * sizeof(int));
    for (int i = 0; i < polygon.size(); i++) {
        in.segmentlist[2 * i] = i;
        in.segmentlist[2 * i + 1] = (i + 1) % polygon.size();
    }
    in.segmentmarkerlist = NULL;
    in.numberofholes = 0;
    in.numberofregions = 0;
    in.holelist = NULL;
    in.regionlist = NULL;
    in.edgelist = NULL;
    in.edgemarkerlist = NULL;
    in.normlist = NULL;
    in.trianglelist = NULL;
    in.triangleattributelist = NULL;
    in.trianglearealist = NULL;
    in.neighborlist = NULL;
    in.numberoftriangles = 0;
    in.numberofcorners = 0;
    in.numberoftriangleattributes = 0;

    // Set Triangle options
    char options[] = "p";
    triangulate(options, &in, &out, NULL);

    // Convert triangulateio structure to QVector<QPolygonF>
    triangles.reserve(out.numberoftriangles);
    for (int i = 0; i < out.numberoftriangles; i++) {
        QPolygonF triangle;
        for (int j = 0; j < 3; j++) {
            int vertexIndex = out.trianglelist[i * 3 + j];
            triangle.append(QPointF(out.pointlist[vertexIndex * 2], out.pointlist[vertexIndex * 2 + 1]));
        }
        triangles.append(triangle);
    }

    // Free memory
    free(in.pointlist);
    free(in.segmentlist);
    free(out.pointlist);
    free(out.segmentlist);
    free(out.trianglelist);

    return triangles;
}

在上面的代码中，我们首先将QPolygonF对象转换为triangulateio结构体对象`in`，然后使用Triangle库的函数进行三角剖分，得到triangulateio结构体对象`out`，最后将`out`转换为QVector<QPolygonF>对象返回。要注意的是，在使用Triangle库的函数进行三角剖分时，可以设置不同的选项，详见Triangle库的文档。