解决使用osgModeling的Loft生成管子时的bug(续)

今天发现有一些情况下, 还是无法生成管道, 排查了一天发现问题好像出在管线头两个点的x完全相同时, 会出这个问题.

 

看了半天的Loft源码, 发现问题出在Loft::considerBasisX函数中:

osg::Vec3 Loft::considerBasisX( const osg::Vec3 basisZ )
{
    osg::Vec3 basisX;
    if ( basisZ.z()!=0.0f )
    {
        if ( osg::equivalent(basisZ.x(),0.0f) && osg::equivalent(basisZ.y(),0.0f) )
            basisX.set( 1.0f, 0.0f, 0.0f );   // basisZ is Z+/Z-
        else
        {
            basisX.set( 1.0f, 1.0f, 0.0f );
            basisX.z() = -(basisZ.x()+basisZ.y()) / basisZ.z();
        }
    }
    else if ( basisZ.y()!=0.0f )
    {
        if ( osg::equivalent(basisZ.x(),0.0f) && osg::equivalent(basisZ.z(),0.0f) )
            basisX.set( 1.0f, 0.0f, 0.0f ); // basisZ is Y+/Y-
        else
        {
            basisX.set( 1.0f, 0.0f, 1.0f );
            basisX.y() = -(basisZ.x()+basisZ.z()) / basisZ.y();
        }
    }
    else if ( basisZ.x()!=0.0f )
    {
        if ( osg::equivalent(basisZ.y(),0.0f) && osg::equivalent(basisZ.z(),0.0f) )
            basisX.set( 0.0f, 0.0f, -basisZ.z() ); // basisZ is X+/X-
        else
        {
            basisX.set( 0.0f, 1.0f, 1.0f );
            basisX.x() = -(basisZ.y()+basisZ.z()) / basisZ.x();
        }
    }
    return basisX;
}

看前两种情况下, 当其他两个值都为0时, basisX都是直接set( 1.0f, 0.0f, 0.0f )的, 为啥到了最后一种情况则是set( 0.0f, 0.0f, -basisZ.z() ), 在这种情况下basisZ.z()明显为0.

 

当把这里改为 basisX.set(0.0f, 0.0f, 1.0f) 程序就正常了.

else if ( basisZ.x()!=0.0f )
{
    if ( osg::equivalent(basisZ.y(),0.0f) && osg::equivalent(basisZ.z(),0.0f) )
        basisX.set( 0.0f, 0.0f, 1.0f ); // basisZ is X+/X-
    else
    {
        basisX.set( 0.0f, 1.0f, 1.0f );
        basisX.x() = -(basisZ.y()+basisZ.z()) / basisZ.x();
     }
}