用OpenSceneGraph实现的NeHe OpenGL教程 - 第二十五课
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简介
NeHe教程在这节课中向我们介绍了如何从文件加载3D模型，并且平滑的从一个模型变换为另一个模型。这个过程又称为逐点动画，点之间的变化过程算法十分简单，采用的是线性的算法。
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实现
首先我们仿照NeHe课程中定义了表示点的结构体以及读取文件的结构体OBJECT并读取文件
void initMorphObject()
{
objload("Data/sphere.txt",&morph1);
objload("Data/torus.txt",&morph2);
objload("Data/tube.txt",&morph3);
objallocate(&morph4,486);
morph4.verts = 486;
for(int i=0;i<486;i++)
{
morph4.points[i].x=((float)(rand()%14000)/1000)-7;
morph4.points[i].y=((float)(rand()%14000)/1000)-7;
morph4.points[i].z=((float)(rand()%14000)/1000)-7;
}
morphGeometry1 = new osg::Geometry;
osg::Vec3Array *vertexArray1 = new osg::Vec3Array;
for (unsigned i = 0; i < morph1.verts; ++i)
{
vertexArray1->push_back(osg::Vec3(morph1.points[i].x, morph1.points[i].y, morph1.points[i].z));
}
morphGeometry1->setVertexArray(vertexArray1);
morphGeometry1->addPrimitiveSet(new osg::DrawArrays(osg::PrimitiveSet::POINTS, 0, 486));
morphGeometry1->setUseDisplayList(false);
srcMorphGeometry = dynamic_cast<osg::Geometry*>(morphGeometry1->clone(osg::CopyOp::DEEP_COPY_ALL));
destMorphGeometry = morphGeometry1;
...
}读取文件之后构建4个几何体对象，接着在几何体更新回调中处理逐个点的变化
上述的处理过程在几何体的更新回调MorphUpdateCallback之中
virtual void update(osg::NodeVisitor*, osg::Drawable* drawable)
{
osg::Geometry *geom = dynamic_cast<osg::Geometry*>(drawable);
if (!geom)
return;
osg::Vec3Array *vertices = dynamic_cast<osg::Vec3Array*>(geom->getVertexArray());
osg::Vec3Array *destVertices = dynamic_cast<osg::Vec3Array*>(_destGeometry->getVertexArray());
if (vertices && destVertices)
{
for (unsigned i = 0; i < vertices->size(); ++i)
{
osg::Vec3 delta = (destVertices->at(i) - vertices->at(i)) / _steps;
vertices->at(i) += delta;
}
vertices->dirty();
}
}在与键盘的交互中设置变换的几何体目标对象：
if (ea.getKey() == osgGA::GUIEventAdapter::KEY_1)
{
MorphUpdateCallback *muc = dynamic_cast<MorphUpdateCallback*>(srcMorphGeometry->getUpdateCallback());
if (!muc)
return false;
muc->setDestGeometry(morphGeometry1);
}
if (ea.getKey() == osgGA::GUIEventAdapter::KEY_2)
{
MorphUpdateCallback *muc = dynamic_cast<MorphUpdateCallback*>(srcMorphGeometry->getUpdateCallback());
if (!muc)
return false;
muc->setDestGeometry(morphGeometry2);
}
通过设置几何体变换的开始形状(srcGeometry)和最终变换到的目标几何体(destGeometry)，在回调中不断调整顶点位置完成动画效果。
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)
/************************************************************************\ * osgNeHe - Copyright (C) 2013-2014 Frank He * * This library is open source and may be redistributed and/or modified under * the terms of the OpenSceneGraph Public License (OSGPL) version 0.0 or * (at your option) any later version. The full license is in LICENSE file * included with this distribution, and on the openscenegraph.org website. * * This library is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. * * A HUGE thanks to NeHe for the OpenGL tutorials< http://nehe.gamedev.net > * * If you've found this code useful, Please let me know. * My E-mail: < [email protected] > * My Blog: < http://blog.csdn.net/csxiaoshui > * \************************************************************************/ #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/Geometry> GLfloat cx,cy,cz = -15.0f; int step=0; int steps = 200; bool morph = false; osg::MatrixTransform *g_transMT = NULL; osg::MatrixTransform *g_rotateX = NULL; osg::MatrixTransform *g_rotateY = NULL; osg::MatrixTransform *g_rotateZ = NULL; struct VERTEX { float x, y, z; }; struct OBJECT { int verts; VERTEX *points; } ; OBJECT morph1,morph2,morph3,morph4; osg::Geometry *morphGeometry1, *morphGeometry2, *morphGeometry3, *morphGeometry4; osg::Geometry *srcMorphGeometry, *destMorphGeometry; void objallocate(OBJECT *k,int n) { k->points=(VERTEX*)malloc(sizeof(VERTEX)*n); } void objfree(OBJECT *k) { free(k->points); } void readstr(FILE *f,char *string) { do { fgets(string, 255, f); } while ((string[0] == '/') || (string[0] == '\n')); return; } void objload(char *name,OBJECT *k) { int ver; float rx,ry,rz; FILE *filein; char oneline[255]; filein = fopen(name, "rt"); readstr(filein,oneline); sscanf(oneline, "Vertices: %d\n", &ver); k->verts=ver; objallocate(k,ver); for (int i=0;i<ver;i++) { readstr(filein,oneline); sscanf(oneline, "%f %f %f", &rx, &ry, &rz); k->points[i].x = rx; k->points[i].y = ry; k->points[i].z = rz; } fclose(filein); } ////////////////////////////////////////////////////////////////////////// class MorphUpdateCallback : public osg::Drawable::UpdateCallback { public: MorphUpdateCallback(osg::Geometry *dest, int steps) : _destGeometry(dest), _steps(steps) { } void setDestGeometry(osg::Geometry *destGeometry) { _destGeometry = destGeometry; } virtual void update(osg::NodeVisitor*, osg::Drawable* drawable) { osg::Geometry *geom = dynamic_cast<osg::Geometry*>(drawable); if (!geom) return; osg::Vec3Array *vertices = dynamic_cast<osg::Vec3Array*>(geom->getVertexArray()); osg::Vec3Array *destVertices = dynamic_cast<osg::Vec3Array*>(_destGeometry->getVertexArray()); if (vertices && destVertices) { for (unsigned i = 0; i < vertices->size(); ++i) { osg::Vec3 delta = (destVertices->at(i) - vertices->at(i)) / _steps; vertices->at(i) += delta; } vertices->dirty(); } } int _steps; osg::Geometry* _destGeometry; }; void initMorphObject() { objload("Data/sphere.txt",&morph1); objload("Data/torus.txt",&morph2); objload("Data/tube.txt",&morph3); objallocate(&morph4,486); morph4.verts = 486; for(int i=0;i<486;i++) { morph4.points[i].x=((float)(rand()%14000)/1000)-7; morph4.points[i].y=((float)(rand()%14000)/1000)-7; morph4.points[i].z=((float)(rand()%14000)/1000)-7; } morphGeometry1 = new osg::Geometry; osg::Vec3Array *vertexArray1 = new osg::Vec3Array; for (unsigned i = 0; i < morph1.verts; ++i) { vertexArray1->push_back(osg::Vec3(morph1.points[i].x, morph1.points[i].y, morph1.points[i].z)); } morphGeometry1->setVertexArray(vertexArray1); morphGeometry1->addPrimitiveSet(new osg::DrawArrays(osg::PrimitiveSet::POINTS, 0, 486)); morphGeometry1->setUseDisplayList(false); srcMorphGeometry = dynamic_cast<osg::Geometry*>(morphGeometry1->clone(osg::CopyOp::DEEP_COPY_ALL)); destMorphGeometry = morphGeometry1; morphGeometry2 = new osg::Geometry; osg::Vec3Array *vertexArray2 = new osg::Vec3Array; for (unsigned i = 0; i < morph2.verts; ++i) { vertexArray2->push_back(osg::Vec3(morph2.points[i].x, morph2.points[i].y, morph2.points[i].z)); } morphGeometry2->setVertexArray(vertexArray2); morphGeometry2->addPrimitiveSet(new osg::DrawArrays(osg::PrimitiveSet::POINTS, 0, 486)); morphGeometry2->setUseDisplayList(false); morphGeometry3 = new osg::Geometry; osg::Vec3Array *vertexArray3 = new osg::Vec3Array; for (unsigned i = 0; i < morph3.verts; ++i) { vertexArray3->push_back(osg::Vec3(morph3.points[i].x, morph3.points[i].y, morph3.points[i].z)); } morphGeometry3->setVertexArray(vertexArray3); morphGeometry3->addPrimitiveSet(new osg::DrawArrays(osg::PrimitiveSet::POINTS, 0, 486)); morphGeometry3->setUseDisplayList(false); morphGeometry4 = new osg::Geometry; osg::Vec3Array *vertexArray4 = new osg::Vec3Array; for (unsigned i = 0; i < morph4.verts; ++i) { vertexArray4->push_back(osg::Vec3(morph4.points[i].x, morph4.points[i].y, morph4.points[i].z)); } morphGeometry4->setVertexArray(vertexArray4); morphGeometry4->addPrimitiveSet(new osg::DrawArrays(osg::PrimitiveSet::POINTS, 0, 486)); morphGeometry4->setUseDisplayList(false); } ////////////////////////////////////////////////////////////////////////// class RotAxisCallback : public osg::NodeCallback { public: RotAxisCallback(const osg::Vec3& axis, double rotSpeed = 0.0, double currentAngle = 0.0) : _rotAxis(axis), _rotSpeed(rotSpeed), _currentAngle(currentAngle){ } virtual void operator()(osg::Node* node, osg::NodeVisitor* nv) { osg::MatrixTransform *rotMT = dynamic_cast<osg::MatrixTransform*>(node); if (!rotMT) return; rotMT->setMatrix(osg::Matrix::rotate(_currentAngle, _rotAxis)); _currentAngle += _rotSpeed; traverse(node, nv); } void setRotateSpeed(double speed) { _rotSpeed = speed; } double getRotateSpeed() const { return _rotSpeed; } private: osg::Vec3 _rotAxis; double _currentAngle; double _rotSpeed; }; ////////////////////////////////////////////////////////////////////////// class ManipulatorSceneHandler : public osgGA::GUIEventHandler { public: ManipulatorSceneHandler() { } virtual bool handle(const osgGA::GUIEventAdapter& ea, osgGA::GUIActionAdapter& aa) { osgViewer::Viewer *viewer = dynamic_cast<osgViewer::Viewer*>(&aa); if (!viewer) return false; if (!viewer->getSceneData()) return false; if (ea.getHandled()) return false; osg::Group *root = viewer->getSceneData()->asGroup(); switch(ea.getEventType()) { case(osgGA::GUIEventAdapter::KEYDOWN): { if (ea.getKey() == osgGA::GUIEventAdapter::KEY_Left) { if (!g_rotateX) return false; RotAxisCallback *rotCallback = dynamic_cast<RotAxisCallback*>(g_rotateX->getUpdateCallback()); if (!rotCallback) return false; double speed = rotCallback->getRotateSpeed(); speed -= 0.02; rotCallback->setRotateSpeed(speed); } if (ea.getKey() == osgGA::GUIEventAdapter::KEY_Right) { if (!g_rotateX) return false; RotAxisCallback *rotCallback = dynamic_cast<RotAxisCallback*>(g_rotateX->getUpdateCallback()); if (!rotCallback) return false; double speed = rotCallback->getRotateSpeed(); speed += 0.02; rotCallback->setRotateSpeed(speed); } if (ea.getKey() == osgGA::GUIEventAdapter::KEY_Up) { if (!g_rotateY) return false; RotAxisCallback *rotCallback = dynamic_cast<RotAxisCallback*>(g_rotateY->getUpdateCallback()); if (!rotCallback) return false; double speed = rotCallback->getRotateSpeed(); speed -= 0.02; rotCallback->setRotateSpeed(speed); } if (ea.getKey()== osgGA::GUIEventAdapter::KEY_Down) { if (!g_rotateY) return false; RotAxisCallback *rotCallback = dynamic_cast<RotAxisCallback*>(g_rotateY->getUpdateCallback()); if (!rotCallback) return false; double speed = rotCallback->getRotateSpeed(); speed += 0.02; rotCallback->setRotateSpeed(speed); } if (ea.getKey()== osgGA::GUIEventAdapter::KEY_Page_Up) { if (!g_rotateZ) return false; RotAxisCallback *rotCallback = dynamic_cast<RotAxisCallback*>(g_rotateZ->getUpdateCallback()); if (!rotCallback) return false; double speed = rotCallback->getRotateSpeed(); speed -= 0.02; rotCallback->setRotateSpeed(speed); } if (ea.getKey()== osgGA::GUIEventAdapter::KEY_Page_Down) { if (!g_rotateZ) return false; RotAxisCallback *rotCallback = dynamic_cast<RotAxisCallback*>(g_rotateZ->getUpdateCallback()); if (!rotCallback) return false; double speed = rotCallback->getRotateSpeed(); speed += 0.02; rotCallback->setRotateSpeed(speed); } if (ea.getKey()== osgGA::GUIEventAdapter::KEY_A) { if (!g_transMT) return false; osg::Matrix transMatrix = g_transMT->getMatrix(); transMatrix.setTrans(transMatrix.getTrans() + osg::Vec3(-0.1, 0, 0)); g_transMT->setMatrix(transMatrix); } if (ea.getKey()== osgGA::GUIEventAdapter::KEY_D) { if (!g_transMT) return false; osg::Matrix transMatrix = g_transMT->getMatrix(); transMatrix.setTrans(transMatrix.getTrans() + osg::Vec3(0.1, 0, 0)); g_transMT->setMatrix(transMatrix); } if (ea.getKey()== osgGA::GUIEventAdapter::KEY_W) { if (!g_transMT) return false; osg::Matrix transMatrix = g_transMT->getMatrix(); transMatrix.setTrans(transMatrix.getTrans() + osg::Vec3(0, 0.1, 0)); g_transMT->setMatrix(transMatrix); } if (ea.getKey()== osgGA::GUIEventAdapter::KEY_S) { if (!g_transMT) return false; osg::Matrix transMatrix = g_transMT->getMatrix(); transMatrix.setTrans(transMatrix.getTrans() + osg::Vec3(0, -0.1, 0)); g_transMT->setMatrix(transMatrix); } if (ea.getKey()== osgGA::GUIEventAdapter::KEY_Q) { if (!g_transMT) return false; osg::Matrix transMatrix = g_transMT->getMatrix(); transMatrix.setTrans(transMatrix.getTrans() + osg::Vec3(0, 0, -0.1)); g_transMT->setMatrix(transMatrix); } if (ea.getKey()== osgGA::GUIEventAdapter::KEY_Z) { if (!g_transMT) return false; osg::Matrix transMatrix = g_transMT->getMatrix(); transMatrix.setTrans(transMatrix.getTrans() + osg::Vec3(0, 0, 0.1)); g_transMT->setMatrix(transMatrix); } if (ea.getKey() == osgGA::GUIEventAdapter::KEY_1) { MorphUpdateCallback *muc = dynamic_cast<MorphUpdateCallback*>(srcMorphGeometry->getUpdateCallback()); if (!muc) return false; muc->setDestGeometry(morphGeometry1); } if (ea.getKey() == osgGA::GUIEventAdapter::KEY_2) { MorphUpdateCallback *muc = dynamic_cast<MorphUpdateCallback*>(srcMorphGeometry->getUpdateCallback()); if (!muc) return false; muc->setDestGeometry(morphGeometry2); } if (ea.getKey() == osgGA::GUIEventAdapter::KEY_3) { MorphUpdateCallback *muc = dynamic_cast<MorphUpdateCallback*>(srcMorphGeometry->getUpdateCallback()); if (!muc) return false; muc->setDestGeometry(morphGeometry3); } if (ea.getKey() == osgGA::GUIEventAdapter::KEY_4) { MorphUpdateCallback *muc = dynamic_cast<MorphUpdateCallback*>(srcMorphGeometry->getUpdateCallback()); if (!muc) return false; muc->setDestGeometry(morphGeometry4); } } default: break; } return false; } }; 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, 1.0) ); 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, 0, 1), osg::Vec3d(0, 0, 0), osg::Vec3d(0, 1, 0)); this->setSceneData( scene ); this->addEventHandler(new ManipulatorSceneHandler); 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() { initMorphObject(); osg::Group *root = new osg::Group; root->getOrCreateStateSet()->setMode(GL_LIGHTING, osg::StateAttribute::OFF | osg::StateAttribute::OVERRIDE); osg::MatrixTransform *mt = new osg::MatrixTransform; g_transMT = mt; mt->setMatrix(osg::Matrix::translate(0, 0, cz)); osg::MatrixTransform *rotX = new osg::MatrixTransform; g_rotateX = rotX; rotX->addUpdateCallback(new RotAxisCallback(osg::X_AXIS)); osg::MatrixTransform *rotY = new osg::MatrixTransform; g_rotateY = rotY; rotY->addUpdateCallback(new RotAxisCallback(osg::Y_AXIS)); osg::MatrixTransform *rotZ = new osg::MatrixTransform; g_rotateZ = rotZ; rotZ->addUpdateCallback(new RotAxisCallback(osg::Z_AXIS)); osg::Geode *geode = new osg::Geode; geode->addDrawable(srcMorphGeometry); srcMorphGeometry->setUpdateCallback(new MorphUpdateCallback(destMorphGeometry,200)); root->addChild(mt); mt->addChild(rotX); rotX->addChild(rotY); rotY->addChild(rotZ); rotZ->addChild(geode); 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(); }