【c++】ObjectARX三点圆弧分段

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【c++】ObjectARX三点圆弧分段
static void DividArc( const AcGePoint3d& spt, const AcGePoint3d& ept, const AcGePoint3d& thirdPt,
                     int count, AcGePoint3dArray& pts )
{
    pts.append( spt );

    AcGeCircArc3d arc( spt, thirdPt, ept );
    AcGePoint3d cnt = arc.center();
    //        double radius = arc.radius();
    AcGeVector3d v1 = spt - cnt;
    AcGeVector3d v2 = ept - cnt;
    int c = ( arc.normal().z > 0 ? 1 : -1 ); // 弧线方向

    double a1 = v1.angleTo( AcGeVector3d::kXAxis, -AcGeVector3d::kZAxis );
    double a2 = v2.angleTo( AcGeVector3d::kXAxis, -AcGeVector3d::kZAxis );

    double dq = abs( a2 - a1 ) / count;
    //acutPrintf(_T("\na1:%.3f, a2:%.3f dq:%.3f c:%d"), a1, a2, dq, c);
    for( int i = 1; i < count; i++ )
    {
        v1.rotateBy( c * dq, AcGeVector3d::kZAxis );
        pts.append( cnt + v1 );
        //acutPrintf(_T("\n点%d:(%d,%d)"),i,pts[i].x,pts[i].y);
    }
    pts.append( ept );
}