scene graph课件.ppt

? Drawable—The Drawable class is the base class for storing geometric data. Drawable is a pure virtual class and can’t be instantiated directly. ? Geometry—The Geometry class, in conjunction with the PrimitiveSet class, act as high-level wrappers around the OpenGL vertex array functionality. Geometry stores the vertex arrays vertex, texture coordinate, color, and normal arrays.;PrimitiveSet—The PrimitiveSet class provides high-level support for the OpenGL vertex array drawing commands. Use this class to specify the types of primitives to draw from the data stored in the associated Geometry class. osg::DrawArray Vector classes (Vec2, Vec3, Vec4.)—OSG provides a set of predefined 2-, 3-, and 4-element vectors of type float or double. Use these vectors to specify vertices, colors, normals, and texture coordinates.;Array classes (Vec2Array, Vec3Array, Vec4Array.)—OSG defines several commonly used array types, such as Vec2Array for texture coordinates. When specifying vertex array data, your application stores geometric data in these arrays before passing them to Geometry objects.;write c++ codes to create an arrow object in the 3D scene.;Scene Graph;1. a Scene Graph ?;2. Scene Graph in OSG;3. Node classes in OSG;3. Node classes in OSG;4. Managing parent nodes;5. Adding models to the scene graph;;6. Transformation nodes;7. osg::MatrixTransform;osg::Matrix;osg::Matrix mat1=osg::Matrix::scale(sx,sy,sz); osg::Matrix mat2=osg::Matrix::translate(tx,ty,tz); osg::Matrix resultMat=mat1*mat2; ;osg::PositionAttitudeTransform;8. performing translations of child nodes;9. Switch nodes;Action – switching between the normal and damaged Cessna;What just happened?;Level-of-detail nodes;Action – constructing a LOD Cessna;Action – constructing a LOD Cessna;What just happened?;Proxy and paging nodes;Action – loading a model at runtime;What just happened?;Customizing your own NodeKits;Action – animating the switch node;Action – animating the switch node;What just happened?;Summary