125 lines
3.5 KiB
C++
125 lines
3.5 KiB
C++
/* -*-c++-*- OpenSceneGraph - Copyright (C) 1998-2006 Robert Osfield
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*
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* This application is open source and may be redistributed and/or modified
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* freely and without restriction, both in commericial and non commericial applications,
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* as long as this copyright notice is maintained.
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*
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* This application is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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*/
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#include <osg/Group>
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#include <osg/Geometry>
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#include <osgDB/ReadFile>
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#include <osgUtil/Optimizer>
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#include <osgViewer/Viewer>
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float random(float min,float max) { return min + (max-min)*(float)rand()/(float)RAND_MAX; }
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struct DrawCallback : public osg::Drawable::DrawCallback
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{
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DrawCallback():
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_firstTime(true) {}
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virtual void drawImplementation(osg::State& state,const osg::Drawable* drawable) const
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{
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if (!_firstTime)
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{
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_previousModelViewMatrix = _currentModelViewMatrix;
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_currentModelViewMatrix = state.getModelViewMatrix();
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_inverseModelViewMatrix.invert(_currentModelViewMatrix);
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osg::Matrix T(_previousModelViewMatrix*_inverseModelViewMatrix);
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osg::Geometry* geometry = dynamic_cast<osg::Geometry*>(const_cast<osg::Drawable*>(drawable));
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osg::Vec3Array* vertices = dynamic_cast<osg::Vec3Array*>(geometry->getVertexArray());
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for(unsigned int i=0;i+1<vertices->size();i+=2)
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{
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(*vertices)[i+1] = (*vertices)[i]*T;
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}
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}
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else
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{
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_currentModelViewMatrix = state.getModelViewMatrix();
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}
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_firstTime = false;
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drawable->drawImplementation(state);
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}
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mutable bool _firstTime;
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mutable osg::Matrix _currentModelViewMatrix;
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mutable osg::Matrix _inverseModelViewMatrix;
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mutable osg::Matrix _previousModelViewMatrix;
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};
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osg::Node* createScene(unsigned int noStars)
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{
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osg::Geometry* geometry = new osg::Geometry;
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// set up vertices
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osg::Vec3Array* vertices = new osg::Vec3Array(noStars*2);
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geometry->setVertexArray(vertices);
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float min = -1.0f;
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float max = 1.0f;
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unsigned int j = 0;
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unsigned int i = 0;
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for(i=0;i<noStars;++i,j+=2)
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{
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(*vertices)[j].set(random(min,max),random(min,max),random(min,max));
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(*vertices)[j+1] = (*vertices)[j]+osg::Vec3(0.0f,0.0f,0.001f);
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}
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// set up colours
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osg::Vec4Array* colours = new osg::Vec4Array(1);
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geometry->setColorArray(colours);
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geometry->setColorBinding(osg::Geometry::BIND_OVERALL);
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(*colours)[0].set(1.0f,1.0f,1.0f,1.0f);
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// set up the primitive set to draw lines
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geometry->addPrimitiveSet(new osg::DrawArrays(GL_LINES,0,noStars*2));
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// set up the points for the stars.
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osg::DrawElementsUShort* points = new osg::DrawElementsUShort(GL_POINTS,noStars);
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geometry->addPrimitiveSet(points);
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for(i=0;i<noStars;++i)
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{
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(*points)[i] = i*2;
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}
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geometry->setUseDisplayList(false);
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geometry->setDrawCallback(new DrawCallback);
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osg::Geode* geode = new osg::Geode;
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geode->addDrawable(geometry);
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geode->getOrCreateStateSet()->setMode(GL_LIGHTING,osg::StateAttribute::OFF);
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osg::Group* group = new osg::Group;
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group->addChild(geode);
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return group;
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}
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int main(int , char **)
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{
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// construct the viewer.
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osgViewer::Viewer viewer;
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// set the scene to render
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viewer.setSceneData(createScene(50000));
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return viewer.run();
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}
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