OSG学习：使用已有回调示例

回调的类型有很多种，一般很容易就想到的是UpdateCallBack，或者EventCallBack，回调的意思就是说，你可以规定在某件事情发生时启动一个函数，这个函数可能做一些事情。这个函数就叫做回调函数。

#include<osg\MatrixTransform>

#include<osg\PositionAttitudeTransform>

#include<osg\Geode>

#include<osgDB\Registry>

#include<osgDB\ReadFile>

#include<osgGA\TrackballManipulator>

#include<osgViewer\Viewer>

//创建一条路径

osg::AnimationPath* createAnimationPath(const osg::Vec3& center, float radius, double looptime)

{

	//路径实体

	osg::AnimationPath* animationPath = new osg::AnimationPath;

	//设置循环模式为LOOP

	animationPath->setLoopMode(osg::AnimationPath::LOOP);

	//设置关键点数

	int numSamples = 40;

	float yaw = 0.0f;

	float yaw_delta = 2.0f*osg::PI / ((float)numSamples - 1.0f);

	float roll = osg::inDegrees(30.0f);

	//设置时间间隔

	double time = 0.0f;

	double time_delta = looptime / (double)numSamples;

	//插入关键点与时间以及旋转角度和位置

	for (int i = 0; i < numSamples; ++i)

	{

		osg::Vec3 position(0, 0, 0);

		osg::Quat rotation(osg::Quat(roll, osg::Vec3(0.0, 1.0, 0.0))*osg::Quat(-(yaw + osg::inDegrees(90.0f)), osg::Vec3(0.0, 0.0, 1.0)));

		//具体插入操作

		animationPath->insert(time, osg::AnimationPath::ControlPoint(position, rotation));

		yaw += yaw_delta;

		time += time_delta;

	}

	return animationPath;

}

//创建移动模型

osg::Node* createMovingModel(const osg::Vec3& center, float radius)

{

	float animationLength = 10.0f;

	//创建的路径

	osg::AnimationPath* animationPath = createAnimationPath(center, radius, animationLength);

	osg::Group* model = new osg::Group;

	//读取模型，并隐藏它下面的第一个节点

	osg::Node* fountain = osgDB::readNodeFile("fountain.osgt");

	fountain->asGroup()->getChild(0)->setNodeMask(0);

	//如果读取成功，则更新赋予它的路径

	if (fountain)

	{

		osg::PositionAttitudeTransform* xform = new osg::PositionAttitudeTransform;

		//设置更新回调

		xform->setUpdateCallback(new osg::AnimationPathCallback(animationPath, 0.0, 1.0));

		//加入子模型节点

		xform->addChild(fountain);

		model->addChild(xform);

	}

	return model;

}

//创建模型

osg::Node* createModel()

{

	osg::Vec3 center(0.0f, 0.0f, 0.0f);

	float radius = 1.0f;

	osg::Group* root = new osg::Group;

	//创建移动的节点，以radius为半径转圈

	osg::Node* movingModel = createMovingModel(center, radius*0.8f);

	//把节点加入到root中并返回

	root->addChild(movingModel);

	return root;

}

//主函数

int main(int argc, char** argv)

{

	osgViewer::Viewer viewer;

	//创建模型

	osg::Node* model = createModel();

	viewer.setSceneData(model);

	viewer.setCameraManipulator(new osgGA::TrackballManipulator());

	viewer.realize();

	return viewer.run();

}

结果图：

巴特西

OSG学习：使用已有回调示例

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