osg.TriangleIndexFunctor

简介

osg.TriangleIndexFunctor是OpenSceneGraph中的一个类，用于遍历三角形列表并对其中的每个三角形进行操作。

API

class TriangleIndexFunctor : public osg::Referenced
{
    public:
        virtual void operator()(unsigned int p1, unsigned int p2, unsigned int p3) = 0;

    protected:
        virtual ~TriangleIndexFunctor() {}
};

• void operator()(unsigned int p1, unsigned int p2, unsigned int p3)：

  该函数会在遍历三角形列表时，对每个三角形调用一次。参数p1、p2、p3分别为三角形顶点的索引。根据需要，可以在该函数中进行相应的操作。

例子

下面是一个简单的例子，展示了如何使用osg.TriangleIndexFunctor来遍历并输出三角形列表中的每个三角形的顶点索引：

#include <osg/Geode>
#include <osg/TriangleIndexFunctor>
#include <osgViewer/Viewer>

class PrintTriangleVertexIndices : public osg::TriangleIndexFunctor
{
public:
    virtual void operator()(unsigned int p1, unsigned int p2, unsigned int p3)
    {
        std::cout << "(" << p1 << ", " << p2 << ", " << p3 << ")" << std::endl;
    }
};

int main()
{
    osg::ref_ptr<osg::Geode> geode = new osg::Geode();
    
    // 添加一个三角形
    osg::ref_ptr<osg::Geometry> geom = new osg::Geometry();
    osg::ref_ptr<osg::Vec3Array> vertices = new osg::Vec3Array();
    vertices->push_back(osg::Vec3(-1, 0, 0));
    vertices->push_back(osg::Vec3(0, 1, 0));
    vertices->push_back(osg::Vec3(1, 0, 0));
    geom->setVertexArray(vertices);
    
    osg::ref_ptr<osg::DrawElementsUInt> indices = new osg::DrawElementsUInt(osg::PrimitiveSet::TRIANGLES, 0);
    indices->push_back(0);
    indices->push_back(1);
    indices->push_back(2);
    geom->addPrimitiveSet(indices);
    
    geode->addDrawable(geom);
    
    // 遍历三角形并输出顶点索引
    PrintTriangleVertexIndices printIndices;
    geom->accept(printIndices);
    
    // 显示场景
    osgViewer::Viewer viewer;
    viewer.setSceneData(geode);
    return viewer.run();
}

输出结果：

(0, 1, 2)

参考资料

• OpenSceneGraph 3.6.5 Documentation - osg::TriangleIndexFunctor