OSG模型控制

标签（空格分隔）： OSG

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OSG中模型控制主要是控制场景中的数据，包括移动、缩放模型、对模型位置求解、隐藏显示模型，不包括视口的控制。

基本操作

基本操作为添加、删除、隐藏、开关模型详细代码为

#ifdef _DEBUG#pragma comment(lib,"osgViewerd.lib")#pragma comment(lib,"osgDBd.lib")#pragma comment(lib,"OpenThreadsd.lib")#pragma comment(lib,"osgd.lib")#else#pragma comment(lib,"osgViewer.lib")#pragma comment(lib,"osgDB.lib")#pragma comment(lib,"OpenThreads.lib")#pragma comment(lib,"osg.lib")#endif#include <osgViewer/viewer>#include <osgDB/readfile>using namespace osg;int main(){    ref_ptr<osgViewer::Viewer> viewer = new osgViewer::Viewer;    viewer->setUpViewOnSingleScreen();    //添加节点    ref_ptr<Group> gp = new Group;    Node* glider = osgDB::readNodeFile("glider.osg");    Node* osgcool = osgDB::readNodeFile("osgcool.osgt");    gp->addChild(glider);    gp->addChild(osgcool);    //删除节点    //gp->removeChild(glider);    //隐藏节点    osgcool->setNodeMask(0);    viewer->setSceneData(gp);    return viewer->run();}

其中隐藏模型是暂时在场景中消失，内存中仍然存在，并且仍在渲染，系统资源并没有减少。开关模型则是在内存中将模型消除。
开关的简单代码如下:

int main(){    ref_ptr<osgViewer::Viewer> viewer = new osgViewer::Viewer;    viewer->setUpViewOnSingleScreen();    //添加节点    ref_ptr<Group> gp = new Group;    Node* glider = osgDB::readNodeFile("glider.osg");    Node* osgcool = osgDB::readNodeFile("osgcool.osgt");    Switch* sw = new Switch();    sw->addChild(glider,false);    sw->addChild(osgcool);    gp->addChild(sw);    viewer->setSceneData(gp);    return viewer->run();}

结果

移动、旋转、缩放

对模型最常见的操作是移动，其次是选择缩放。OSG通常将模型放在场景中央。
移动旋转缩放都是对模型节点的矩阵乘法操作。在OSG中，矩阵可以当作某个节点的子节点加入场景中。代码为

#ifdef _DEBUG#pragma comment(lib,"osgViewerd.lib")#pragma comment(lib,"osgDBd.lib")#pragma comment(lib,"OpenThreadsd.lib")#pragma comment(lib,"osgd.lib")#else#pragma comment(lib,"osgViewer.lib")#pragma comment(lib,"osgDB.lib")#pragma comment(lib,"OpenThreads.lib")#pragma comment(lib,"osg.lib")#endif#include <osgViewer/viewer>#include <osgDB/readfile>#include <osg/MatrixTransform>using namespace osg;int main(){    ref_ptr<osgViewer::Viewer> viewer = new osgViewer::Viewer;    viewer->setUpViewOnSingleScreen();    //添加节点    ref_ptr<Group> gp = new Group;    Node* osgcool = osgDB::readNodeFile("osgcool.osgt");    gp->addChild(osgcool);    //z轴向上平移2个单位    ref_ptr<MatrixTransform> trans = new MatrixTransform;    trans->setMatrix(Matrix::translate(0, 0, 2));    trans->addChild(osgcool);    //缩小1倍并z轴向下平移2个单位    ref_ptr<MatrixTransform> scale = new MatrixTransform;    scale->setMatrix(Matrix::scale(.5f, .5f, .5f) * Matrix::translate(0, 0, -2));    scale->addChild(osgcool);    //缩小1倍并z轴向下平移2个单位 x轴向右平移2个单位 再x轴旋转45度    ref_ptr<MatrixTransform> rot = new MatrixTransform;    rot->setMatrix(Matrix::rotate(DegreesToRadians(45.0f),1.f,.0f,.0f) *        Matrix::scale(.5f, .5f, .5f) * Matrix::translate(4, 0, -2));    rot->addChild(osgcool);    gp->addChild(trans);    gp->addChild(scale);    gp->addChild(rot);    viewer->setSceneData(gp);    return viewer->run();}