clipPlane的相关问题

wulingxia

设置了两个clipPlane，如何让二者以任意角度相交进行剖面？

array

参看osgclip例子

wulingxia

    osg::ref_ptr<osg::ClipPlane>  m_clipPlane0 = new osg::ClipPlane;
    osg::ref_ptr<osg::ClipPlane>  m_clipPlane1 = new osg::ClipPlane;
    m_clipPlane0->setClipPlane(0,0,-1,0);
    m_clipPlane1->setClipPlane(0,1,0,0);
    clipnode->addClipPlane(m_clipPlane0);
    clipnode->addClipPlane(m_clipPlane1);

只显示m_clipPlane1的切割结果

liuzhiyu123

Geometry is always clipped against the boundaries of a six-plane frustum in x, y, and z. glClipPlane allows the specification of additional planes, not necessarily perpendicular to the x, y, or Z axis, against which all geometry is clipped. To determine the maximum number of additional clipping planes, call glGetIntegerv with argument GL_MAX_CLIP_PLANES. All implementations support at least six such clipping planes. Because the resulting clipping region is the intersection of the defined half-spaces, it is always convex.

glClipPlane specifies a half-space using a four-component plane equation. When glClipPlane is called, equation is transformed by the inverse of the modelview matrix and stored in the resulting eye coordinates. Subsequent changes to the modelview matrix have no effect on the stored plane-equation components. If the dot product of the eye coordinates of a vertex with the stored plane equation components is positive or zero, the vertex is \f2in\f1 with respect to that clipping plane. Otherwise, it is out.

To enable and disable clipping planes, call glEnable and glDisable with the argument GL_CLIP_PLANEi, where i is the plane number.

All clipping planes are initially defined as (0, 0, 0, 0) in eye coordinates and are disabled.

wulingxia

在OpenGL中使用glEnable就能唤醒，但在OSG中怎么设置，才能显示多个面共同截取的效果？

liuzhiyu123

ClipPlane 的序号，您没有设置它的序号，默认都是0那么在state中怎么分辨？

wulingxia

您说的对，现在可以啦！另外，怎样实现沿着Z轴旋转ClipPlane呢？

wulingxia

        std::vector<osg::ClipPlane*>    m_clipPlane;
        osg::ref_ptr<osg::ClipPlane>  m_clipPlane0 = new osg::ClipPlane;

        for ( int i = 0 ; i < 2; i++)
        {
                switch(i)
                {
                case 0:
                        m_clipPlane0->setClipPlane(1,0,0,0);
                        m_clipPlane0->setClipPlaneNum(0);
                        break;

                default:
                        m_clipPlane0->setClipPlane(0,1,0,0);
                        m_clipPlane0->setClipPlaneNum(1);
                        break;
                }
                m_clipPlane.push_back(m_clipPlane0);
        }
调试时，循环开始时是对的，但最后一次循环时，会再执行一次m_clipPlane0->setClipPlaneNum(0);语句，导致两个截面的序号都为1！怎么回事？

wulingxia

wulingxia 发表于 2013-4-7 17:41
std::vector    m_clipPlane;
        osg::ref_ptr  m_clipPlane0 = new osg::ClipPlane;

是智能指针的问题！嘿嘿