osgEarth目标选择 |
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osgEarth目标选择
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osgEarth目标拾取
本文展示了一种目标选择的方法。通过将osg::Node注册到osgEarth的对象管理器中，利用osgEarth的RTTPicker类以及重写的RTTPicker::Callback类，实现目标的选中，最后利用osgEarth::VirtualProgram类，将拾取的对象高亮显示。 本文主要解决以下问题： osgEarth::RTTPicker实现目标拾取RTTPicker::Callback回调解析osgEarth::VirtualProgram目标高亮显示目录 1 前言2 osgEarth::RTTPicker与RTTPicker::Callback实现目标拾取3 osgEarth::VirtualProgram目标高亮显示内容 1 前言osgEarth中标注之类的鼠标拾取操作和普通的碰撞检测拾取不太一样，PlaceNode和其它的标注类型不是在通常的场景空间中渲染的，而是作为屏幕空间的叠加层来渲染的，不能通过碰撞检测获取求交的对象。 osgEarth中有一个例子Sample osgearth_pick，演示了如何通过RTTPicker技术实现场景中对象的选取。加入到场景中的矢量和注记都能用鼠标拾取到，但对于普通的模型数据却获取不到。可以通过注册的方式，将加入到场景中的osg::Node进行注册，osgEarth中ObjectIndex类管理着对象的注册，其提供了接口用于加入到场景中的osg::Node进行注册。 2 osgEarth::RTTPicker与RTTPicker::Callback实现目标拾取首先osgEarth解析.earth文件从而构建场景，场景中可以有地形、影像、矢量、模型等数据，而本篇文章主要实现对模型数据的拾取；接着将拾取的节点进行注册；然后由鼠标进行目标拾取。 从外部earth文件导入节点： C:/Geoway/SVN/gwEarth/trunk/osgearth/data/streetlight.osgb.(0,0,3.14).trans.100.scale如上为.earth文件中的内容，包含两个部分：模型图层和视点图层。模型图层采用Model关键字，其中url字段表示模型的位置路径，location字段表示模型上球的位置和viewpoints图层；视点图层用viewpoints关键字来表示，其包含了 name、heading、lat、long、height、pitch和range七个参数，分别表示图层名称、方位角、位置纬度、经度、高度、俯仰角、范围。 ui::VBox* uiContainer = new ui::VBox(); uiContainer->setAlign( ui::Control::ALIGN_LEFT, ui::Control::ALIGN_TOP ); uiContainer->setAbsorbEvents( true ); uiContainer->setBackColor(0,0,0,0.8); uiContainer->addControl( new ui::LabelControl("RTT Picker Test", osg::Vec4(1,1,0,1)) ); uiContainer->addControl( new ui::ButtonControl("Toggle picker", new TogglePicker(app)) ); app.fidLabel = new ui::LabelControl("---"); uiContainer->addControl( app.fidLabel ); app.nameLabel = uiContainer->addControl( new ui::LabelControl( "---" ) ); // Load up the earth file. osg::Node* node = MapNodeHelper().load( arguments, &app.viewer, uiContainer );代码段2为从外部earth文件导入得到osg::Node的代码，得到的osg::Node包含两个子节点，分别为MapNode和Controls::ControlCanvas, ControlCanvas包含四个LabelControl和一个ButtonControl，用来控制对象拾取的开启与关闭，以及对象信息的展示。 接下来是开启目标拾取功能，同时实现对象的注册： struct App { App(osg::ArgumentParser& args) : viewer(args), mainView(NULL), mapNode(NULL), picker(NULL), fidLabel(NULL), nameLabel(NULL), highlightUniform(NULL) { } osgViewer::CompositeViewer viewer; osgViewer::View* mainView; osgEarth::MapNode* mapNode; osgEarth::Util::RTTPicker* picker; ui::LabelControl* fidLabel; ui::LabelControl* nameLabel; osg::Uniform* highlightUniform; }; void startPicker(App& app) { // Note! Must stop and restart threading when removing the picker // because it changes the OSG View/Slave configuration. app.viewer.stopThreading(); app.picker = new RTTPicker(); app.mainView->addEventHandler(app.picker); ResistryNodeVisitor rn; app.mapNode->accept(rn); // add the graph that will be picked. app.picker->addChild(app.mapNode); // install a callback that controls the picker and listens for hits. app.picker->setDefaultCallback(new MyPickCallback(app)); app.viewer.startThreading(); }代码段1为一结构体，主要包含一视图、主视图、MapNode以及Util::RTTPicker；代码段2为开启节点拾取功能，RTTPicker继承自osgGA::GUIEventHandler，可将其作为事件直接加入到视图中；ResistryNodeVisitor为一访问器，实现节点的注册，其核心代码为：osgEarth::Registry::objectIndex()->tagNode(&node, &node); tageNode的英文解释为： /** * Inserts the object into the index, and tags the Node with a uniform containing * the object id. Returns the Object ID. */ 即将一对象（第二个参数）插入到index表中，同时将 一osg::Uniform对象写入到节点中（第一个参数）。 最后设置RTTPicker的CallBack。RTTPicker类继承自osgGA::GUIEventHandler，其重写了handle函数，handle函数中调用了runPicks函数，runPicks调用了checkForPickResult函数，checkForPickResult函数调用了RTTPlicker::CallBack中的onHit函数，本文通过重写RTTPicker::CallBack中的onHit()函数实现拾取对象的获取： struct MyPickCallback : public RTTPicker::Callback { App& _app; MyPickCallback(App& app) : _app(app) { } void onHit(ObjectID id) { // First see whether it's a feature: FeatureIndex* index = Registry::objectIndex()->get(id).get(); Feature* feature = index ? index->getFeature( id ) : 0L; if ( feature ) { _app.fidLabel->setText( Stringify() loadShaders( vp ); // A uniform that will tell the shader which object to highlight: app.highlightUniform = new osg::Uniform("objectid_to_highlight", 0u); stateSet->addUniform(app.highlightUniform ); }通过VirtualProgram设置节点着色器和片元着色器，实现对特定ID的节点，高亮显示。 最后完整代码如下： /* -*-c++-*- */ /* osgEarth - Geospatial SDK for OpenSceneGraph * Copyright 2020 Pelican Mapping * http://osgearth.org * * osgEarth is free software; you can redistribute it and/or modify * it under the terms of the GNU Lesser General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS * IN THE SOFTWARE. * * You should have received a copy of the GNU Lesser General Public License * along with this program. If not, see */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #define LC "[rttpicker] " using namespace osgEarth; using namespace osgEarth::Util; namespace ui = osgEarth::Util::Controls; //----------------------------------------------------------------------- //! Application-wide data. struct App { App(osg::ArgumentParser& args) : viewer(args), mainView(NULL), mapNode(NULL), picker(NULL), fidLabel(NULL), nameLabel(NULL), highlightUniform(NULL) { } osgViewer::CompositeViewer viewer; osgViewer::View* mainView; osgEarth::MapNode* mapNode; osgEarth::Util::RTTPicker* picker; ui::LabelControl* fidLabel; ui::LabelControl* nameLabel; osg::Uniform* highlightUniform; }; //! Callback that you install on the RTTPicker. struct MyPickCallback : public RTTPicker::Callback { App& _app; MyPickCallback(App& app) : _app(app) { } void onHit(ObjectID id) { // First see whether it's a feature: FeatureIndex* index = Registry::objectIndex()->get(id).get(); Feature* feature = index ? index->getFeature( id ) : 0L; if ( feature ) { _app.fidLabel->setText( Stringify() loadShaders( vp ); // A uniform that will tell the shader which object to highlight: app.highlightUniform = new osg::Uniform("objectid_to_highlight", 0u); stateSet->addUniform(app.highlightUniform ); } class ResistryNodeVisitor : public osg::NodeVisitor { public: ResistryNodeVisitor() : osg::NodeVisitor(TRAVERSE_ALL_CHILDREN) { } ~ResistryNodeVisitor() { } void apply(osg::Geometry& node) { osgEarth::Registry::objectIndex()->tagNode(&node, &node); //_geometries.push_back(&node); traverse(node); } public: /*const std::vector& pagedlods() { return _pagedlods; } const std::vector& geometries() { return _geometries; } void clear() { _geometries.clear(); _pagedlods.clear(); }*/ private: /*std::vector _geometries; std::vector _pagedlods;*/ }; //------------------------------------------------------------------------ // Configures a window that lets you see what the RTT camera sees. //void //setupRTTView(osgViewer::View* view, osg::Texture* rttTex) //{ // view->setCameraManipulator(0L); // view->getCamera()->setName( "osgearth_pick RTT view" ); // view->getCamera()->setViewport(0,0,256,256); // view->getCamera()->setClearColor(osg::Vec4(1,1,1,1)); // view->getCamera()->setProjectionMatrixAsOrtho2D(-.5,.5,-.5,.5); // view->getCamera()->setViewMatrixAsLookAt(osg::Vec3d(0,-1,0), osg::Vec3d(0,0,0), osg::Vec3d(0,0,1)); // view->getCamera()->setProjectionResizePolicy(osg::Camera::FIXED); // // osg::Vec3Array* v = new osg::Vec3Array(6); // (*v)[0].set(-.5,0,-.5); (*v)[1].set(.5,0,-.5); (*v)[2].set(.5,0,.5); (*v)[3].set((*v)[2]); (*v)[4].set(-.5,0,.5);(*v)[5].set((*v)[0]); // // osg::Vec2Array* t = new osg::Vec2Array(6); // (*t)[0].set(0,0); (*t)[1].set(1,0); (*t)[2].set(1,1); (*t)[3].set((*t)[2]); (*t)[4].set(0,1); (*t)[5].set((*t)[0]); // // osg::Geometry* g = new osg::Geometry(); // g->setUseVertexBufferObjects(true); // g->setUseDisplayList(false); // g->setVertexArray( v ); // g->setTexCoordArray( 0, t ); // g->addPrimitiveSet( new osg::DrawArrays(GL_TRIANGLES, 0, 6) ); // // osg::Geode* geode = new osg::Geode(); // geode->addDrawable( g ); // // osg::StateSet* stateSet = geode->getOrCreateStateSet(); // stateSet->setDataVariance(osg::Object::DYNAMIC); // // stateSet->setTextureAttributeAndModes(0, rttTex, 1); // rttTex->setUnRefImageDataAfterApply( false ); // rttTex->setResizeNonPowerOfTwoHint(false); // // GLUtils::setLighting(stateSet, 0); // stateSet->setMode(GL_CULL_FACE, 0); // stateSet->setAttributeAndModes(new osg::BlendFunc(GL_ONE, GL_ZERO), 1); // // const char* fs = // "#version " GLSL_VERSION_STR "\n" // "void swap(inout vec4 c) { c.rgba = c==vec4(0)? vec4(1) : vec4(vec3((c.r+c.g+c.b+c.a)/4.0),1); }\n"; // osgEarth::Registry::shaderGenerator().run(geode); // VirtualProgram::getOrCreate(geode->getOrCreateStateSet())->setFunction("swap", fs, ShaderComp::LOCATION_FRAGMENT_COLORING); // // view->setSceneData( geode ); //} void startPicker(App& app) { // Note! Must stop and restart threading when removing the picker // because it changes the OSG View/Slave configuration. app.viewer.stopThreading(); app.picker = new RTTPicker(); app.mainView->addEventHandler(app.picker); ResistryNodeVisitor rn; app.mapNode->accept(rn); // add the graph that will be picked. app.picker->addChild(app.mapNode); // install a callback that controls the picker and listens for hits. app.picker->setDefaultCallback(new MyPickCallback(app)); // Make a view that lets us see what the picker sees. /* if (app.rttView == NULL) { app.rttView = new osgViewer::View(); app.rttView->getCamera()->setGraphicsContext(app.mainView->getCamera()->getGraphicsContext()); app.rttView->getCamera()->setSmallFeatureCullingPixelSize(-1.0f); app.viewer.addView(app.rttView); } setupRTTView(app.rttView, app.picker->getOrCreateTexture(app.mainView)); app.rttView->getCamera()->setNodeMask(~0);*/ app.viewer.startThreading(); } void stopPicker(App& app) { // Note! Must stop and restart threading when removing the picker // because it changes the OSG View/Slave configuration. app.viewer.stopThreading(); //app.viewer.removeView(app.rttView); //app.rttView->getCamera()->setNodeMask(0); app.mainView->removeEventHandler(app.picker); app.picker = 0L; app.viewer.startThreading(); } struct TogglePicker : public ui::ControlEventHandler { App& _app; TogglePicker(App& app) : _app(app) { } void onClick(Control* button) { if (_app.picker == 0L) startPicker(_app); else stopPicker(_app); } }; //----------------------------------------------------------------------- int usage(const char* name) { OE_NOTICE setCameraManipulator( new EarthManipulator() ); // Made some UI components: ui::VBox* uiContainer = new ui::VBox(); uiContainer->setAlign( ui::Control::ALIGN_LEFT, ui::Control::ALIGN_TOP ); uiContainer->setAbsorbEvents( true ); uiContainer->setBackColor(0,0,0,0.8); uiContainer->addControl( new ui::LabelControl("RTT Picker Test", osg::Vec4(1,1,0,1)) ); uiContainer->addControl( new ui::ButtonControl("Toggle picker", new TogglePicker(app)) ); app.fidLabel = new ui::LabelControl("---"); uiContainer->addControl( app.fidLabel ); app.nameLabel = uiContainer->addControl( new ui::LabelControl( "---" ) ); // Load up the earth file. osg::Node* node = MapNodeHelper().load( arguments, &app.viewer, uiContainer ); if ( node ) { app.mainView->setSceneData( node ); app.mapNode = MapNode::get(node); // start with a picker running startPicker(app); // Highlight features as we pick'em. installHighlighter(app); app.mainView->getCamera()->setName( "Main view" ); return app.viewer.run(); } else { return usage(argv[0]); } }运行的结果如下：
总结： 本文介绍了osgEarth中目标拾取的用法，通过重写RTTPicker::CallBack，获取拾取的对象，然后借用shader将拾取的对象高亮。本文只介绍了osgEarth目标拾取的用法，接下来会进一步分析其原理，研究RTTPicker类及osgEarth的注册系统。 |
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