OSG绘制金字塔geode+动态纹理坐标

osg::Node* createPyramidModel()
{
    // create the root node which will hold the model.
    osg::Group* root = new osg::Group();

    // turn off lighting
    root->getOrCreateStateSet()->setMode(GL_LIGHTING, osg::StateAttribute::OFF);

    osg::Geode* pyramidGeode = new osg::Geode();
    osg::Geometry* pyramidGeometry = new osg::Geometry();
    pyramidGeode->setUpdateCallback(new TextureCoordUpdateCallback(0.01));
    pyramidGeode->setDataVariance(osg::Object::DYNAMIC);
    pyramidGeode->addDrawable(pyramidGeometry);
    root->addChild(pyramidGeode);

    osg::Vec3Array* pyramidVertices = new osg::Vec3Array;
    pyramidVertices->push_back(osg::Vec3(0, 0, 0)); // 左前 
    pyramidVertices->push_back(osg::Vec3(10, 0, 0)); // 右前 
    pyramidVertices->push_back(osg::Vec3(10, 10, 0)); // 右后 
    pyramidVertices->push_back(osg::Vec3(0, 10, 0)); // 左后 
    pyramidVertices->push_back(osg::Vec3(5, 5, 10)); // 塔尖
    pyramidGeometry->setVertexArray(pyramidVertices);
    osg::DrawElementsUInt* pyramidBase = new osg::DrawElementsUInt(osg::PrimitiveSet::QUADS, 0);
    pyramidBase->push_back(3);
    pyramidBase->push_back(2);
    pyramidBase->push_back(1);
    pyramidBase->push_back(0);
    pyramidGeometry->addPrimitiveSet(pyramidBase);
    osg::DrawElementsUInt* pyramidFaceOne = new osg::DrawElementsUInt(osg::PrimitiveSet::TRIANGLES, 0);
    pyramidFaceOne->push_back(0);
    pyramidFaceOne->push_back(1);
    pyramidFaceOne->push_back(4);
    pyramidGeometry->addPrimitiveSet(pyramidFaceOne);
    osg::DrawElementsUInt* pyramidFaceTwo = new osg::DrawElementsUInt(osg::PrimitiveSet::TRIANGLES, 0);
    pyramidFaceTwo->push_back(1);
    pyramidFaceTwo->push_back(2);
    pyramidFaceTwo->push_back(4);
    pyramidGeometry->addPrimitiveSet(pyramidFaceTwo);
    osg::DrawElementsUInt* pyramidFaceThree = new osg::DrawElementsUInt(osg::PrimitiveSet::TRIANGLES, 0);
    pyramidFaceThree->push_back(2);
    pyramidFaceThree->push_back(3);
    pyramidFaceThree->push_back(4);
    pyramidGeometry->addPrimitiveSet(pyramidFaceThree);
    osg::DrawElementsUInt* pyramidFaceFour = new osg::DrawElementsUInt(osg::PrimitiveSet::TRIANGLES, 0);
    pyramidFaceFour->push_back(3);
    pyramidFaceFour->push_back(0);
    pyramidFaceFour->push_back(4);
    pyramidGeometry->addPrimitiveSet(pyramidFaceFour);

    osg::Vec4Array* colors = new osg::Vec4Array;
    colors->push_back(osg::Vec4(1.0f, 0.0f, 0.0f, 1.0f)); //红色    
    colors->push_back(osg::Vec4(0.0f, 1.0f, 0.0f, 1.0f)); //绿色    
    colors->push_back(osg::Vec4(0.0f, 0.0f, 1.0f, 1.0f)); //蓝色    
    colors->push_back(osg::Vec4(1.0f, 1.0f, 1.0f, 1.0f)); //白色
    pyramidGeometry->setColorArray(colors);
    pyramidGeometry->setColorBinding(osg::Geometry::BIND_PER_VERTEX);

    osg::Vec3Array* normals = new osg::Vec3Array(1);
    (*normals)[0].set(0.0f, -1.0f, 0.0f);
    pyramidGeometry->setNormalArray(normals, osg::Array::BIND_OVERALL);

    osg::Vec2Array* texcoords = new osg::Vec2Array(5);
    (*texcoords)[0].set(0.00f, 0.0f);
    (*texcoords)[1].set(0.25f, 0.0f);
    (*texcoords)[2].set(0.50f, 0.0f);
    (*texcoords)[3].set(0.75f, 0.0f);
    (*texcoords)[4].set(0.50f, 1.0f);
    pyramidGeometry->setTexCoordArray(0, texcoords);

    // set up the texture state.
    osg::Texture2D* texture = new osg::Texture2D;
    texture->setDataVariance(osg::Object::DYNAMIC); // protect from being optimized away as static state.
    texture->setFilter(osg::Texture2D::MIN_FILTER, osg::Texture2D::LINEAR);
    texture->setFilter(osg::Texture2D::MAG_FILTER, osg::Texture2D::LINEAR);
    texture->setWrap(osg::Texture2D::WRAP_S, osg::Texture2D::REPEAT);
    texture->setWrap(osg::Texture2D::WRAP_T, osg::Texture2D::REPEAT);
    texture->setImage(osgDB::readImageFile("Images/road.png"));
    osg::StateSet* stateset = pyramidGeometry->getOrCreateStateSet();
    stateset->setTextureAttributeAndModes(0, texture, osg::StateAttribute::ON);

    return root;
}

class TextureCoordUpdateCallback : public osg::NodeCallback
{
public:

    TextureCoordUpdateCallback(double delay = 1.0) :
        _delay(delay),
        _prevTime(0.0)
    {
    }

    virtual void operator()(osg::Node* node, osg::NodeVisitor* nv)
    {
        if (nv->getFrameStamp())
        {
            double currTime = nv->getFrameStamp()->getSimulationTime();
            if (currTime - _prevTime > _delay)
            {
                osg::Geode* geode = node->asGeode();
                osg::Geometry* geom = geode->getDrawable(0)->asGeometry();
                // 获取纹理坐标数组
                osg::Array* tmp = geom->getTexCoordArray(0);
                osg::Vec2Array* coorArray = (osg::Vec2Array*) tmp;
                auto it = coorArray->begin();
                for (; it < coorArray->end(); it++)
                {
                    // 动起来
                    it->x() += 0.001;
                }
                // 更新纹理坐标数组
                geom->setTexCoordArray(0, coorArray);

                // record time
                _prevTime = currTime;
            }
        }
    }


protected:
    double                          _delay;
    double                          _prevTime;

};