Easy Studierstube Applications with a little help from OpenInventor

Easy Studierstube Applicationswith a little help from OpenInventor Gerhard Reitmayr Vienna University of Technology

Stb application requirements • User interface design needs iterative development. • Need to be adapted to different user interface modalities. • Demos need to be kept alive ! • Reuse of application features is very desirable.

User interface components icon 3D window PIP widgets pen content

Structure of an application Application Widgets Different modalities SoMyContextKit Reuse this ? Scene graph Different presentation styles

Skeleton of an application SoApplicationKit { contextKit SomeApplication { templatePipSheet Separator { # your PIP sheet widgets } windowGroup Group { # content and windows ! } # all kinds of application # specific fields } }

Use the file format ! • Let your application become an understandable part of an OIV file. • Use fields as inputs and outputs of applications. • Build scene graphs in the OIV file instead of in code. • Try to write all applications as pure OIV nodekits !

Fields as inputs/outputs • Connecting to widgets • Callbacks tie you to the type of widget • Lower abstraction used then necessarye.g. observe 3 buttons instead of a 3 valued state variable. • Use fields that represent exactly the state the application needs. • Output states as fields allows simple change of presentation.

OIV: Observing changes • Sensors are the callbacks of OIV ! • SoFieldSensor • Only one field per sensor • Not ref counted > take care yourself • SoNodeSensor • Reports changes on node / sub scene graph • Beware of node fields

Scene graphs as parameters • Use node fields • As templates for complex scene graphs • Use parts • For scene graphs that need traversal • Use conventions • Node type, e.g. set a texture to be picked up by geometry in the graph • Search for a given name, type and change its fields

Parameterized scene graphs • Using context sensitive traversal • New element SoContextElement • Maps int -> int • Context[3] = 2 • Context[-5] = NIL • SoContext to modify context during traversal • SoContextSwitch (…) • Modify traversal depending on context

Context Example Group Context2->1 Context2->0 ContextSwitchindex[2] Geometry Colorgreen Colorred

OIV : NodeKits - concept • A nodekit represents a tightly integrated template scene graph with meaning to the developer. • We get • Fixed scene graph • Represented by a node • Internal connections • OIV interface of fields and children

Nodekit structure Root node Private parts Public parts SoTrackedArtifaktKit

OIV : setUpConnections • Central method to establish connections within a nodekit. • Signals nodekit when the structure changes. • Important for • Correct loading of applications • Distributed OpenInventor

OIV : setupConnections

Navigation app – 1

Navigation app - 2 • DEF NavKit NavigationContext { • waypoint ["Karlskirche",… ] • waypointPosition [0 1 0,… ] • edge [1,… ] • numEdge [3,… ] • userPosition = SoTrakEngine{}.translation • destination = USE waypointList.selected • path [“Karlskirche”,… ] • edgeIndex [1,2,3] nodeIndex [2,3,5,10] • templatePipSheet SoPipSheetKit {…} • windowGroup So3DSeparator {…} • }

Thank you • ?

SoClassLoader • Load OIV classes from within a file ! classLoader SoClassLoader { className "MyOIVNode" fileName "../somewhere/mynodes" } MyOIVNode { … }

Timing issues • Delayed execution • SoOneShotSensor • SoAlarmSensor • Repeated actions • SoTimeSensor • SoIdleSensor

Stb Applications • Applications are OpenInventor nodekits • Subclasses of SoContextKit • Implementation as shared library (dll,so) • Additional callback API for • User specific data • Distribution

Writing STB applications • SoApplicationKit • SoClassLoader • SoContextKit • templatePipSheet • windowGroup

Interfacing SoContextKit • Use fields as interface • Avoid connections based on names, pointers, etc • Special patterns for multi user applications • Use localized search

PIP - personal interaction panel System Sheet App 1 PipSheet PIP PipSheet 1 App 2 User PipSheet 2

PIP Komponenten window tab system tab sheet tab

Remedy – OpenInventor • A set of guidelines to • Structure application API • Structure data flow in application • Modularize applications • OpenInventor can support us here !

Beispiel : hello world SoApplicationKit { contextKit SoContextKit { windowGroup DEF Hello Group { Material {diffuseColor 0.9 0.95 0.3} Scale {scaleFactor 0.1 0.1 0.1} Font { size 1 } Text3 { string ["Hello", "World !"] justification CENTER parts ALL } } templatePipSheet USE Hello } }

Guidelines • Data driven implementation • Store all data in fields or children • React to changes and update internal and dependent state • > Very flexible • > Highly reusable components

Lifetime of an application Loading SoMyAppKit checkPipGeometry()checkWindowGeometry() checkPipConnections()checkPipMasterMode() focusChange() windowEventCB() Initialisation per user Interaction

Easy Studierstube Applications with a little help from OpenInventor