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This article mainly introduces "how to derive triangular data from OpenSceneGraph". In daily operation, I believe many people have doubts about how to derive triangular data from OpenSceneGraph. The editor consulted all kinds of materials and sorted out simple and easy-to-use operation methods. I hope it will be helpful for you to answer the doubts about "how to derive triangular data from OpenSceneGraph". Next, please follow the editor to study!

In OpenSceneGraph development, some data that are not triangular slices, such as quadrilaterals, are often used for convenience. For example, drawing a tube with a quadrilateral band is much easier to calculate than using a triangle. For example, now that we are going to draw a face made up of two planes, I can do this:

Osg::Geode* geode=new osg::Geode;osg::Geometry* polyGeom = new osg::Geometry;osg::Vec3 myCoords [] = {osg::Vec3, osg::Vec3; int numCoords = sizeof (myCoords) / sizeof (osg::Vec3); osg::Vec3Array* vertices = new osg::Vec3Array (numCoords,myCoords) PolyGeom- > setVertexArray (vertices); polyGeom- > addPrimitiveSet (new osg::DrawArrays (osg::PrimitiveSet::QUAD_STRIP,0,numCoords)); geode- > addDrawable (polyGeom)

In this way, two planes are drawn with six points and the QUAD_STRIP method provided by OpenGL. However, if this plane is to be used in techniques such as collision detection, it is necessary to convert the quadrilateral bands represented by these six points into triangular slices. These triangles are fixed as follows:

01 00 0 01 1 00 0 01 0 01 1 01 1 01 0 02 1 01 0 02 0 02 1 0

You can see that the two planes are made up of four triangles, and both are arranged counterclockwise (facing the same direction). I have done the conversion myself before, but I feel very troublesome. OpenSceneGraph's Example osggeometry provides a printTriangles function that prints out all the triangular slices of drawable, regardless of the initial data structure:

Struct NormalPrint {void operator () (const osg::Vec3& v1 osg::Vec3& v2) Const osg::Vec3& v3, bool) const {osg::Vec3 normal = (v2-v1) ^ (v3-v2); normal.normalize (); std::cout setDrawBuffer (GL_BACK); camera- > setReadBuffer (GL_BACK); osgGA::TrackballManipulator* tm=new osgGA::TrackballManipulator;viewer.setCameraManipulator (tm); viewer.addSlave (camera.get ()); / / Set up root nodeosg::ref_ptr root=new osg::Group Root- > addChild (createGeode ()); / / Start showshowviewer.setSceneData (root.get ()); viewer.realize (); while (! viewer.done ()) {viewer.frame ();}} this is the end of the study on "how OpenSceneGraph derives triangular data", hoping to solve everyone's doubts. The collocation of theory and practice can better help you learn, go and try it! If you want to continue to learn more related knowledge, please continue to follow the website, the editor will continue to work hard to bring you more practical articles!

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