有图有真相：

以下是点集序列或数组创建凸多边形的代码：

#include
#include
#include

#pragma comment(lib, "cv.lib")
#pragma comment(lib, "cxcore.lib")
#pragma comment(lib, "highgui.lib")

#define ARRAY 0

int main()
{
IplImage* img = cvCreateImage (cvSize(500, 500), 8, 3);
cvNamedWindow ("hull", 1);

#if ! ARRAY
CvMemStorage* storage = cvCreateMemStorage (0);
#endif
int i;
int contour = rand() % 100 + 1;
int hullcontour;
CvPoint pt0;
#if ! ARRAY
CvSeq* ptseq = cvCreateSeq (CV_SEQ_KIND_GENERIC | CV_32SC2, sizeof(CvContour), sizeof(CvPoint), storage);
CvSeq* hull;
for (i = 0; i < contour; i++)
{
pt0.x = rand() % (img->width / 2) + img->width / 4;
pt0.y = rand() % (img->height / 2) + img->height / 4;
cvSeqPush (ptseq, &pt0);
}
hull = cvConvexHull2 (ptseq, 0, CV_CLOCKWISE, 0);
/*hull = cvConvexHull2 (ptseq, 0, CV_CLOCKWISE, 1);*/
hullcontour = hull->total;
#else
CvPoint* points = (CvPoint*)malloc(contour * sizeof(points[0]));
int* hull = (int*)malloc(contour * sizeof(hull[0]));
CvMat point_mat = cvMat (1, contour, CV_32SC2, points);
CvMat hull_mat = cvMat (1, contour, CV_32SC1, hull);
for (i = 0; i < contour; i++)
{
pt0.x = rand() % (img->width / 2) + img->width / 4;
pt0.y = rand() % (img->height / 2) + img->height / 4;
points[i] = pt0;
}
cvConvexHull2 (&point_mat, &hull_mat, CV_CLOCKWISE, 0);
hullcontour = hull_mat.cols;
#endif
cvZero (img);
for (i = 0; i < contour; i++)
{
#if ! ARRAY
pt0 = * CV_GET_SEQ_ELEM(CvPoint, ptseq, i);
/*pt0 = ** CV_GET_SEQ_ELEM(CvPoint*, ptseq, i);*/
#else
pt0 = points[i];
#endif
cvCircle (img, pt0, 2, CV_RGB(255, 0, 0), CV_FILLED);
}
#if ! ARRAY
pt0 = ** CV_GET_SEQ_ELEM(CvPoint*, hull, hullcontour - 1);
/*pt0 = * CV_GET_SEQ_ELEM(CvPoint, hull, hullcontour - 1);*/
#else
pt0 = points[hull[hullcontour - 1]];
#endif

for (i = 0; i < hullcontour; i++)
{
#if ! ARRAY
CvPoint pt = **CV_GET_SEQ_ELEM(CvPoint*, hull, i);
/*CvPoint pt = *CV_GET_SEQ_ELEM(CvPoint, hull, i);*/
#else
CvPoint pt = points[hull[i]];
#endif
cvLine (img, pt0, pt, CV_RGB(255, 0, 0));
pt0 = pt;
}

cvShowImage ("hull", img);

cvWaitKey (0);

#if ! ARRAY
cvClearMemStorage (storage);
#else
free (points);
free (hull);
#endif

return 0;
}