Open Inventor A short introduction

Capabilities of Open Inventor Easy construction of 3D scenes User interaction Animation

Overview Open Inventor is a “scenegraph“ graphics API: All visible objects are stored in a scenegraph Built on top of OpenGL

Scenegraph Anatomy There are three kinds of nodes: Group nodes: allow construction of trees Property nodes: change the color / location /... of the next object Shapes: visible objects

Common node types Group nodes SoGroup  SoSeparator, SoSwitch,... Property nodes Transform: SoTransform, SoRotation,... Appearance: SoMaterial, SoDrawStyle,... Shape nodes SoShape  SoCone, SoCube, SoText2,...

Scene objects class name prefix: So (scene object) derived from SoNode can be inserted directly into the scenegraph Example: root->addChild(new SoSphere)

Fields class name prefix: SoSF/SoMF (Single Field/Multiple Field) public attributes of Scene objects specify the appearance of scene objects (like radius, height, color...)

... Fields Newly created scene Objects have fields with default values Fields can be “connected“ to other fields Fields can be changed using setValue(s): Example: SoSphere *sphere = new SoSphere;... sphere->radius.setValue(3);

Typical Open Inventor code... SoSeparator *root = new SoSeparator; SoTranslation *t = new SoTranslation; t->translation.setValue(2, 0, 0); root->addChild(t); root->addChild(new SoCube);...

Loading Scenes Loading scenes is very easy: SoInput scene; scene.openFile("chessboard.iv"); root = SoDB::readAll(&scene);

Advanced Topics Manipulators allow the user to modify the scene Actions compute bounding boxes, picks objects... Sensors can detect changes in the scene and invoke callback functions Engines can animate the scene

A few tips... Follow the setup tutorial for Coin3D! You need a new So... class? You need a new #include statement! Don‘t forget to insert your nodes into the scene graph!

Resources Coin3D: A free implementation of Open Inventor Inventor Mentor: A good online reference book Another presentation: peninventor.ppt peninventor.ppt dev-gallery: Some simple tutorials gallery.com/programming/openInventor/main.htmlwww.dev- gallery.com/programming/openInventor/main.html