Beispiel #1
0
// 功能: 判断一点是否在一多边形范围内
GEOMAPI MgPtInAreaRet mgPtInArea(
    const Point2d& pt, int count, const Point2d* vertexs, 
    int& order, const Tol& tol)
{
    int i;
    int odd = 1;    // 1: 交点数为偶数, 0: 交点数为奇数
    
    order = -1;
    for (i = 0; i < count; i++)
    {
        // P与某顶点重合. 返回 kMgPtAtVertex, order = 顶点号 [0, count-1]
        if (pt.isEqualTo(vertexs[i], tol))
        {
            order = i;
            return kMgPtAtVertex;
        }
    }
    
    for (i = 0; i < count; i++)
    {
        const Point2d& p1 = vertexs[i];
        const Point2d& p2 = (i+1 < count) ? vertexs[i+1] : vertexs[0];
        
        // P在某条边上. 返回 kMgPtOnEdge, order = 边号 [0, count-1]
        if (mgIsBetweenLine2(p1, p2, pt, tol))
        {
            order = i;
            return kMgPtOnEdge;
        }

        if (!PtInArea_Edge(odd, pt, p1, p2, 
            i > 0 ? vertexs[i-1] : vertexs[count-1]))
            continue;
    }

    // 如果射线和多边形的交点数为偶数, 则 p==1, P在区外, 返回 kMgPtOutArea
    // 为奇数则p==0, P在区内, 返回 kMgPtInArea
    return 0 == odd ? kMgPtInArea : kMgPtOutArea;
}