Open Inventor

A short introduction

Capabilities of Open Inventor

Easy construction of 3D scenesUser interactionAnimation

Overview

Open Inventor is a “scenegraph“ graphics API: All visible objects are stored in a scenegraphBuilt 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 SoNodecan 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 objectsspecify the appearance of scene

objects (like radius, height, color ...)

... Fields

Newly created scene Objects have fields with default valuesFields can be “connected“ to other fieldsFields 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 sceneActions compute bounding boxes, picks objects ...Sensors can detect changes in the scene and invoke callback functionsEngines 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 www.coin3d.orgInventor Mentor: A good online reference bookAnother presentation: http://vrlab.postech.ac.kr/vr/gallery/edu/vr/openinventor.pptdev-gallery: Some simple tutorials www.dev-gallery.com/programming/openInventor/main.html