Open Inventor Programming

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Open Inventor Programming

• Beifang Yi
• 2004 July

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Open Inventor Programming

• Based on the following references
• Orange Book(Inventor Mentor)
• Coin3d On-line Document(http//doc.coin3d.org)
• Green Book(Inventor Manual)
• Red Book(OpenGL Programming)
• Purple Book (Inventor Toolmaker)

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Open Inventor Programming

• Without mentioning to the reference source, the
  contents are assumed to come from the Orange
  Book The Inventor Mentor, Programming
  Object-Oriented 3D Graphics with Open Inventor,
  Release 2.

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1. Overview

• What is Open Inventor?
• Open Inventor is a library of objects and methods
  used to create interactive 3D graphics
  applications.
• Inventor objects include
• database primitives (shape, property, group, and
  engine objects),
• interactive manipulators (handle box and
  trackball),
• and components (material editor, directional
  light editor, and examiner viewer).

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1. Overview

• What is Open Inventor?
• Inventor architecture

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1. Overview

• What is Open Inventor?
• Inventor represents an object-oriented
  application policy built on top of OpenGL,
  providing a programming model and user interface
  for OpenGL programs.
• The Inventor toolkit is window System
  independent.

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1. Overview

• Objects, not Drawings
• Introduction
• All information about these objects (shape, size,
  coloring, texture, location in 3D space) is
  stored in a scene database.
• This information can be used in a variety of ways
  -- The most common use is to display (or render)
  an image of the 3D objects on the screen.
• For many 3D graphics packages, this image is the
  ultimate goal -- a photorealistic representation
  on the screen of a 3D scene.

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1. Overview

• Objects, not Drawings
• Introduction
• But what if you want to change the scene, or
  interact with it?
• With Open Inventor, the ability to make these
  changes is built into the programming model.

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1. Overview

• Objects, not Drawings
• Using database objects in a variety of ways
• Because the Inventor database holds information
  about the objects as they exist in their 3D
  "world" (not just as a 2D array of pixels) other
  operations in addition to rendering can be
  performed.
• The objects in the scene can be picked,
  highlighted, and manipulated as discrete
  entities.
• Bounding-box calculations can be performed on
  them.
• They can be printed, searched for, read from a
  file, and written to a file.

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1. Overview

• Animation
• Inventor Objects can also encapsulate behavior
  into the description stored in the scene database.

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1. Overview

• How does Open Inventor Relate to OpenGL?
• Open Inventor uses OpenGL for rendering.
• In OpenGL the rendering is explicit, whereas in
  Inventor, rendering (along with other operations)
  is encapsulated in the objects.

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1. Overview

• The Inventor ToolKit
• The Scene Database
• Node
• The node is the basic building block to create
  three-dimensional scene databases in Inventor.
• Each node holds a piece of information (surface
  material, shape description, geometric
  transformation, light, or camera)

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1. Overview

• The Inventor ToolKit
• The Scene Database
• Scene Graph
• An ordered collection of nodes is referred to as
  a scene graph.
• The scene graph is stored in the Inventor
  database.
• Inventor takes care of storing and managing the
  scene graph in the database .

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1. Overview

• Scene Graph Symbols

• Scene Graph Example

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1. Overview

• The Inventor ToolKit
• The Scene Database
• Actions
• After you have constructed a scene graph, you can
  apply a number of operations or actions to it,
  including rendering, picking, searching,
  computing a bounding box, or writing o a file.

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1. Overview

• The Inventor ToolKit
• The Scene Database
• Classes of database primitives
• shape nodes sphere, cube, cylinder, quad mesh.
• property nodes material, lighting model,
  textures, environment
• group nodes separator, level-of-detail, switch
• engines provide animation
• sensors timing based or change based

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1. Overview

• The Inventor ToolKit
• Node Kits
• Overview
• Node kits facilitate the creation of structured,
  consistent databases.
• Each node kit is a collection of nodes with a
  specified arrangement.

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1. Overview

• The Inventor ToolKit
• Node Kits
• Example SoShapeKit
• Used for any inventor shape object.
• If you use this node kit, you don't have to
  create and arrange each node individually.
• By default it contains an SoCube node, and it
  allows a material, geometric transformation, and
  other properties to be inserted in the correct
  place when required.

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1. Overview

• The Inventor ToolKit
• Node Kits
• Another use of node kits is to define
  application-specific objects and semantics. For
  example, airplane animation
• Each airplane consists of the same general scene
  graph structure fuselage, wings, and landing
  gear.
• As well as some airplane-specific methods
  BankLeft(), RaiseLandingGear().
• There is no need to know the structure of the
  subgraph representing the landing gear to raise
  it, since the general method, RaiseLandingGear(),
  exists.

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1. Overview

• The Inventor ToolKit
• Manipulators
• A special kind of node that reacts to user
  interface events and can be edited directly by
  the user.
• By picking on a handle and dragging it, the user
  can change the scale and position of the box and
  the object inside of it.
• Manipulators provide an easy way for
  applications to incorporate direct 3D
  interaction.
• Example our example 2-3.

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1. Overview

• Inventor Component Library
• Provides window-system support and integration
  with the X-Window System.
• This library includes
• A render area (window) object
• Main loop and initialization convenience routines
• An event translator
• Editors
• Viewers
• Example 2-4

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1. Overview

• Inventor Component Library
• The render area accepts an X event, translates it
  into an Inventor event, and then passes it to
  "smart" objects, such as manipulators, that may
  handle the event.
• Components are reusable modules that contain both
  a render area and a user interface.
• They are used for editing scene graph nodes
  (materials, lights, transformations) as well as
  for viewing scenes in different ways.

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1. Overview

• Inventor Component Library
• Component Example

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1. Overview

• Inventor Class Tree(leftBase classes, right the
  derived)

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1. Overview

• Inventor Class Tree(leftBase classes, right the
  derived)

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1. Overview

• Inventor Class Tree(leftBase classes, right the
  derived)

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1. Overview

• Extending the Toolkit
• One of the most important aspects of Inventor is
  the ability to program new objects and operations
  as extensions to the toolkit.
• One way to extend the set of objects provided is
  to derive new classes from existing ones (See
  Purple Book).
• Another way is by using callback functions. A
  callback function is a user-written function that
  is called under certain conditions.