用OpenSceneGraph实现的NeHe OpenGL教程 - 第三十八课

• 简介

这节课NeHe教我们怎样把图片作为资源嵌入到exe可执行文件中，这样当我们发布程序的时候就可以不需要附带上图片文件了。由于这部分的内容和OSG并没有关系，主要是使用Windows编程中资源的概念，我对这部分并不是很熟悉，因此本课只实现最后的效果。图片并未处理成NeHe中的这种方式。

• 实现

首先创建我们需要的50只蝴蝶的模型，并且加载需要的纹理

void initialize()
{
	for (int loop=0; loop<50; loop++)
	{
		setObject(loop);
	}

	g_Tex1 = new osg::Texture2D;
	g_Tex1->setFilter(osg::Texture::MAG_FILTER, osg::Texture::LINEAR);
	g_Tex1->setFilter(osg::Texture::MAG_FILTER, osg::Texture::LINEAR);
	g_Tex1->setImage(osgDB::readImageFile("Data/Butterfly1.bmp"));

	g_Tex2 = new osg::Texture2D;
	g_Tex2->setFilter(osg::Texture::MAG_FILTER, osg::Texture::LINEAR);
	g_Tex2->setFilter(osg::Texture::MAG_FILTER, osg::Texture::LINEAR);
	g_Tex2->setImage(osgDB::readImageFile("Data/Butterfly2.bmp"));

	g_Tex3 = new osg::Texture2D;
	g_Tex3->setFilter(osg::Texture::MAG_FILTER, osg::Texture::LINEAR);
	g_Tex3->setFilter(osg::Texture::MAG_FILTER, osg::Texture::LINEAR);
	g_Tex3->setImage(osgDB::readImageFile("Data/Butterfly3.bmp"));
}

接下来把蝴蝶添加到组节点中，并设置每只蝴蝶的位置回调函数，更新它们的位置

osg::Group*		createButterflyGroup()

在回调中写下蝴蝶的位置变化以及旋转变化等：

class ButterFlyGroupCallback : public osg::NodeCallback

class TranslateUpdateCallback : public osg::NodeCallback

这些内容前面的课程中已经重复很多次了，相信不难理解，具体代码参见后面的附录部分：

将所有这些部分添加到场景根节点下，编译运行程序：

附：本课源码(源码中可能存在错误和不足，仅供参考)

#include "../osgNeHe.h"

#include <QtCore/QTimer>
#include <QtGui/QApplication>
#include <QtGui/QVBoxLayout>

#include <osgViewer/Viewer>
#include <osgDB/ReadFile>
#include <osgQt/GraphicsWindowQt>

#include <osg/MatrixTransform>
#include <osg/PolygonMode>
#include <osg/Texture2D>
#include <osg/BlendFunc>

osg::Texture2D *g_Tex1, *g_Tex2, *g_Tex3;

struct object
{
	int   tex;
	float x;
	float y;
	float z;
	float yi;
	float spinz;
	float spinzi;
	float flap;
	float fi;
};

object obj[50];

void setObject(int loop)
{
	obj[loop].tex=rand()%3;
	obj[loop].x=rand()%34-17.0f;
	obj[loop].y=18.0f;
	obj[loop].z=-((rand()%30000/1000.0f)+10.0f);
	obj[loop].spinzi=(rand()%10000)/5000.0f-1.0f;
	obj[loop].flap=0.0f;	
	obj[loop].fi=0.05f+(rand()%100)/1000.0f;	
	obj[loop].yi=0.001f+(rand()%1000)/10000.0f;
}


void initialize()
{
	for (int loop=0; loop<50; loop++)
	{
		setObject(loop);
	}

	g_Tex1 = new osg::Texture2D;
	g_Tex1->setFilter(osg::Texture::MAG_FILTER, osg::Texture::LINEAR);
	g_Tex1->setFilter(osg::Texture::MAG_FILTER, osg::Texture::LINEAR);
	g_Tex1->setImage(osgDB::readImageFile("Data/Butterfly1.bmp"));

	g_Tex2 = new osg::Texture2D;
	g_Tex2->setFilter(osg::Texture::MAG_FILTER, osg::Texture::LINEAR);
	g_Tex2->setFilter(osg::Texture::MAG_FILTER, osg::Texture::LINEAR);
	g_Tex2->setImage(osgDB::readImageFile("Data/Butterfly2.bmp"));

	g_Tex3 = new osg::Texture2D;
	g_Tex3->setFilter(osg::Texture::MAG_FILTER, osg::Texture::LINEAR);
	g_Tex3->setFilter(osg::Texture::MAG_FILTER, osg::Texture::LINEAR);
	g_Tex3->setImage(osgDB::readImageFile("Data/Butterfly3.bmp"));
}


class ButterflyUpdateCallback : public osg::Drawable::UpdateCallback
{
public:
	ButterflyUpdateCallback(int index, int texIndex) : _index(index), _texIndex(texIndex)
	{
		//NOP
	}

	virtual void update(osg::NodeVisitor*, osg::Drawable* drawable)
	{
		osg::Geometry *geometry = dynamic_cast<osg::Geometry*>(drawable);
		if(!geometry)
			return;

		osg::Vec3Array *vertexArray = dynamic_cast<osg::Vec3Array*>(geometry->getVertexArray());
		if (!vertexArray)
			return;

		vertexArray->clear();
		vertexArray->push_back(osg::Vec3(1.0f, 1.0f, 0.0f));
		vertexArray->push_back(osg::Vec3(-1.0f, 1.0f, obj[_index].flap));
		vertexArray->push_back(osg::Vec3(-1.0f,-1.0f, 0.0f));
		vertexArray->push_back(osg::Vec3(1.0f, 1.0f, 0.0f));
		vertexArray->push_back(osg::Vec3(-1.0f,-1.0f, 0.0f));
		vertexArray->push_back(osg::Vec3(1.0f,-1.0f, obj[_index].flap));
		vertexArray->dirty();
		geometry->setVertexArray(vertexArray);

		if (!geometry->getOrCreateStateSet()->getTextureAttribute(0, osg::StateAttribute::TEXTURE))
		{
			if (_texIndex == 0 )
			{
				geometry->getOrCreateStateSet()->setTextureAttributeAndModes(0, g_Tex1);
			}
			if (_texIndex == 1)
			{
				geometry->getOrCreateStateSet()->setTextureAttributeAndModes(0, g_Tex2);
			}
			if (_texIndex == 2)
			{
				geometry->getOrCreateStateSet()->setTextureAttributeAndModes(0, g_Tex3);
			}
		}
	}

	int _index;
	int _texIndex;
};


class RotateUpdateCallback : public osg::NodeCallback
{
public:
	RotateUpdateCallback(int index) : _index(index){ }

	virtual void operator()(osg::Node* node, osg::NodeVisitor* nv)
	{
		osg::MatrixTransform *mt = dynamic_cast<osg::MatrixTransform*>(node);
		if (!mt)
			return;
		mt->setMatrix(osg::Matrix::rotate(osg::DegreesToRadians(obj[_index].spinz), osg::Z_AXIS));

		traverse(node, nv);
	}

	int _index;
};


class TranslateUpdateCallback : public osg::NodeCallback
{
public:
	TranslateUpdateCallback(int index) : _index(index){}

	virtual void operator()(osg::Node* node, osg::NodeVisitor* nv)
	{
		osg::MatrixTransform *mt = dynamic_cast<osg::MatrixTransform*>(node);
		if (!mt)
			return;
		mt->setMatrix(osg::Matrix::translate(obj[_index].x,obj[_index].y,obj[_index].z));

		traverse(node, nv);
	}

	int _index;
};


class ButterFlyGroupCallback : public osg::NodeCallback
{
public:
	ButterFlyGroupCallback(){}

	virtual void operator()(osg::Node* node, osg::NodeVisitor* nv)
	{
		for (int loop = 0; loop < 50; ++loop)
		{
			obj[loop].y-=obj[loop].yi;
			obj[loop].spinz+=obj[loop].spinzi;
			obj[loop].flap+=obj[loop].fi;

			if (obj[loop].y<-18.0f)
			{
				setObject(loop);
			}

			if ((obj[loop].flap>1.0f) || (obj[loop].flap<-1.0f))
			{
				obj[loop].fi=-obj[loop].fi;
			}
		}
		traverse(node, nv);
	}
};



osg::Group*		createButterflyGroup()
{
	osg::Group *butterflyGroup = new osg::Group;
	butterflyGroup->addUpdateCallback(new ButterFlyGroupCallback);

	for (int loop = 0; loop < 50; ++loop)
	{
		osg::MatrixTransform *zoomMT = new osg::MatrixTransform;
		zoomMT->setMatrix(osg::Matrix::translate(obj[loop].x,obj[loop].y,obj[loop].z));
		zoomMT->addUpdateCallback(new TranslateUpdateCallback(loop));
		osg::MatrixTransform *rotateX = new osg::MatrixTransform;
		rotateX->setMatrix(osg::Matrix::rotate(osg::DegreesToRadians(45.0), osg::X_AXIS));
		osg::MatrixTransform *rotateZ = new osg::MatrixTransform;
		rotateZ->setMatrix(osg::Matrix::rotate(osg::DegreesToRadians(obj[loop].spinz), osg::Z_AXIS));
		rotateZ->addUpdateCallback(new RotateUpdateCallback(loop));

		osg::Geode *butterflyGeode = new osg::Geode;
		osg::Geometry *butterGeometry = new osg::Geometry;
		butterGeometry->setUpdateCallback(new ButterflyUpdateCallback(loop, obj[loop].tex));
		osg::Vec3Array *vertexArray = new osg::Vec3Array;
		osg::Vec2Array *texArray = new osg::Vec2Array;

		vertexArray->push_back(osg::Vec3(1.0f, 1.0f, 0.0f));
		vertexArray->push_back(osg::Vec3(-1.0f, 1.0f, obj[loop].flap));
		vertexArray->push_back(osg::Vec3(-1.0f,-1.0f, 0.0f));
		vertexArray->push_back(osg::Vec3(1.0f, 1.0f, 0.0f));
		vertexArray->push_back(osg::Vec3(-1.0f,-1.0f, 0.0f));
		vertexArray->push_back(osg::Vec3(1.0f,-1.0f, obj[loop].flap));

		texArray->push_back(osg::Vec2(1.0f,1.0f));
		texArray->push_back(osg::Vec2(0.0f,1.0f));
		texArray->push_back(osg::Vec2(0.0f,0.0f));
		texArray->push_back(osg::Vec2(1.0f,1.0f));
		texArray->push_back(osg::Vec2(0.0f, 0.0f));
		texArray->push_back(osg::Vec2(1.0f,0.0f));

		butterGeometry->setVertexArray(vertexArray);
		butterGeometry->addPrimitiveSet(new osg::DrawArrays(osg::PrimitiveSet::TRIANGLES, 0, vertexArray->size()));
		butterGeometry->setTexCoordArray(0, texArray, osg::Array::BIND_PER_VERTEX);
		butterGeometry->getOrCreateStateSet()->setMode(GL_LIGHTING, false);
		osg::BlendFunc *blendFunc = new osg::BlendFunc(osg::BlendFunc::ONE, osg::BlendFunc::SRC_ALPHA);
		butterGeometry->getOrCreateStateSet()->setAttributeAndModes(blendFunc);
		butterGeometry->getOrCreateStateSet()->setMode(GL_DEPTH_TEST, false);

		butterflyGeode->addDrawable(butterGeometry);
		butterflyGroup->addChild(zoomMT);
		zoomMT->addChild(rotateX);
		rotateX->addChild(rotateZ);
		rotateZ->addChild(butterflyGeode);
	}
	
	return butterflyGroup;
}



class ViewerWidget : public QWidget, public osgViewer::Viewer
{
public:
	ViewerWidget(osg::Node *scene = NULL)
	{
		QWidget* renderWidget = getRenderWidget( createGraphicsWindow(0,0,640,480), scene);

		QVBoxLayout* layout = new QVBoxLayout;
		layout->addWidget(renderWidget);
		layout->setContentsMargins(0, 0, 0, 1);
		setLayout( layout );

		connect( &_timer, SIGNAL(timeout()), this, SLOT(update()) );
		_timer.start( 10 );
	}

	QWidget* getRenderWidget( osgQt::GraphicsWindowQt* gw, osg::Node* scene )
	{
		osg::Camera* camera = this->getCamera();
		camera->setGraphicsContext( gw );

		const osg::GraphicsContext::Traits* traits = gw->getTraits();

		camera->setClearColor( osg::Vec4(0.0, 0.0, 0.0, 0.5) );
		camera->setViewport( new osg::Viewport(0, 0, traits->width, traits->height) );
		camera->setProjectionMatrixAsPerspective(45.0f, static_cast<double>(traits->width)/static_cast<double>(traits->height), 0.1f, 100.0f );		
		camera->setViewMatrixAsLookAt(osg::Vec3d(0.0f, 25.0f, -45.0f), osg::Vec3d(0, 0, 0), osg::Vec3d(0, 1, 0));

		this->setSceneData( scene );

		return gw->getGLWidget();
	}

	osgQt::GraphicsWindowQt* createGraphicsWindow( int x, int y, int w, int h, const std::string& name="", bool windowDecoration=false )
	{
		osg::DisplaySettings* ds = osg::DisplaySettings::instance().get();
		osg::ref_ptr<osg::GraphicsContext::Traits> traits = new osg::GraphicsContext::Traits;
		traits->windowName = name;
		traits->windowDecoration = windowDecoration;
		traits->x = x;
		traits->y = y;
		traits->width = w;
		traits->height = h;
		traits->doubleBuffer = true;
		traits->alpha = ds->getMinimumNumAlphaBits();
		traits->stencil = ds->getMinimumNumStencilBits();
		traits->sampleBuffers = ds->getMultiSamples();
		traits->samples = ds->getNumMultiSamples();

		return new osgQt::GraphicsWindowQt(traits.get());
	}

	virtual void paintEvent( QPaintEvent* event )
	{ 
		frame(); 
	}

protected:

	QTimer _timer;
};



osg::Node*	buildScene()
{
	initialize();

	osg::Group *root = new osg::Group;
	root->addChild(createButterflyGroup());
	return root;
}



int main( int argc, char** argv )
{
	QApplication app(argc, argv);
	ViewerWidget* viewWidget = new ViewerWidget(buildScene());
	viewWidget->setGeometry( 100, 100, 640, 480 );
	viewWidget->show();
	return app.exec();
}