SceneOrbiter Class Reference
[Nodes]

[PREVIEW] Tool class for building a basic interactive OpenInventor application with mode-less scene "orbiter" viewing behavior. More...

#include <Inventor/ViewerComponents/nodes/SceneOrbiter.h>

Inheritance diagram for SceneOrbiter:

List of all members.

Public Types
enum	RotationMethod { TURNTABLE, TRACKBALL }
Public Member Functions
	SceneOrbiter ()
virtual	~SceneOrbiter ()
void	setConstraintLevel (float level)
float	getConstraintLevel ()
void	setRotationMethod (RotationMethod method)
RotationMethod	getRotationMethod ()
void	setUpAxis (openinventor::inventor::Axis::Type axis)
openinventor::inventor::Axis::Type	getUpAxis ()
void	enableViewingCube (bool enabled)
bool	isViewingCubeEnabled () const
SoViewingCube *	getViewingCube ()
virtual void	setCameraMode (SceneInteractor::CameraMode mode)

Detailed Description

[PREVIEW] Tool class for building a basic interactive OpenInventor application with mode-less scene "orbiter" viewing behavior.

The SceneOrbiter is an extension of the SceneInteractor node that provides camera and headlight manipulations like panning, zooming and orbiting similar to the classic Open Inventor "Examiner" viewer classes (e.g. SoWinExaminerViewer) and the SceneExaminer (in Orbit navigation mode).

The SceneOrbiter provides a "mode-less" viewer which is very convenient for users. The Examiner viewer and SceneExaminer viewers are always in either viewing mode (mouse events control the camera) or in selection mode (mouse events are sent to the scene graph and objects can be selected). This often requires the user to frequently switch between viewing and selection mode (for example by pressing the ESC key) while interacting with the scene. SceneOrbiter does not have modes. For example, a mouse click without moving the mouse is interpreted as a selection and the event is sent to the scene graph, but a mouse click and "drag" is interpreted as controlling the camera.

The SceneOrbiter provides two different methods to control the rotation of the camera around the scene : trackball and turntable, see RotationMethod enum.
The trackball method allows the camera to move along any circular orbit around the scene and look in the direction of its center. The orbit orientation can change at any time while interpreting a mouse drag. Thus the trackball is known as an unconstrained orbiting mode. The trackball is the unique method used by the historical examiner viewer and by the SceneExaminer.
The additional turntable method is a more constrained orbiting mode. It lets the camera move only along vertical orbits such as the earth meridians, and along horizontal circles such as the earth parallels. The vertical orbits and the horizontal circles are related to an up axis, which can be changed calling setUpAxis. The horizontal circles are centered around this up axis, and the vertical orbits share their south and north pole on this up axis. As the camera cannot move along any other circle, this mode is more constrained compared to the trackball mode. However, it provides a more natural navigation experience when viewing a scene that has strong vertical and horizontal references. For instance, when orbiting in turntable mode around a scene representing the Eiffel tower, this one always looks vertical on your screen. Compared to the trackball mode, the turntable mode does not need any tedious small mousemove correction to keep the scene well aligned with the borders of the screen.

The 'headlight', an SoDirectionalLight node, is automatically aligned with the camera's view direction.

An SoViewingCube node is automatically added to the scene. The viewing cube can be hidden by calling the enableViewingCube() method. Note that the up axis of the viewing cube is synchronized with the up axis of the SceneOrbiter.

See parent class SceneInteractor for more details about the structure of the internal scene graph.

The SceneOrbiter uses an instance of SoCameraInteractor to manipulate the camera in response to OpenInventor events.

Notes:

Window system integration
The SceneOrbiter needs a component that integrates the Open Inventor 3D rendering window with the native window system. System dependent tasks include creating a window, placing the window in the application's user interface, initializing OpenGL and processing the native event/message loop. System independent support for this is provided by the SoRenderAreaCore class. Example components are provided for various window systems, for example, WinRenderArea for native Microsoft Windows.

Event handling
The SceneOrbiter needs a component that builds OpenInventor events (SoEvent) from native system events. System independent support for this is provided by the SoEventBuilder class. Example components are provided for various window systems, for example, WinEventToSoEvent for native Microsoft Windows.

Library
A basic version of SceneOrbiter is a supported part of the Open Inventor API and a prebuilt library is provided.

Source code
The basic version of SceneOrbiter is also provided as source code to allow applications to customize and build their own interactive tool class.
See $OIVHOME/source/Inventor/ViewerComponents/nodes.

Scene graph
The application scene graph should be the last child of the SceneOrbiter. The initial application scene graph can be added by simply calling the inherited method addChild(). But note that if you need to replace the application scene graph, for example loading a new data set, do not call removeAllChildren(). That would also remove the SceneOrbiter's camera, headlight and event handler nodes. Add an SoSeparator to the SceneOrbiter to serve as the "scene graph holder", then add and remove the application scene graph from this node.

Clip planes
SceneOrbiter automatically adjusts the 'near' and 'far' clipping planes when events modifying the camera are handled. This adjustment, based on the bounding box of the scene, ensures that shapes will not be clipped as the camera orbits and also that depth buffer precision is maximized.
Note: Updating clipping planes after a camera move can be insufficient. If the scene graph is modified or if a dragger or a rendered shape is moved, they can disappear or become partially clipped. A classic implementation of a render area must adjust clipping planes before each rendering by calling the provided method adjustClippingPlanes(). See render area's implementations available in $OIVHOME/source/Inventor/gui folder for examples of adjustClippingPlanes use.

Compatibility with classical viewers
Please note that some interaction behaviors are different from the classic Open Inventor viewer classes (e.g. SoXtExaminerViewer):
- Left Mouse + Shift does Zoom in/out.
- The Mouse wheel performs a dolly relative to the cursor position, not the center of the viewport.
- The classic ESC key behavior is not implemented.
  (Not necessary because viewing and selection are supported without separate modes.)
- The classic Alt key behavior is not implemented. This key is reserved for application use.
- The Right Mouse button does not display a popup menu. This button is reserved for application use.
- Seek mode is not supported.

Compatibility with SceneExaminer
- Only the left mouse button has defined behaviors.
  Pan and zoom behaviors require pressing a keyboard key while dragging the mouse.

USAGE

Left Mouse: Rotate the scene.
Left Mouse + Ctrl: Pan the scene.
Left Mouse + Shift: Zoom in/out.
Mouse Wheel: Zoom in/out (zoom center is the mouse cursor location).

Member Enumeration Documentation

enum SceneOrbiter::RotationMethod

Defines how the mouse events or touch events control the rotations of the scene.

Enumerator:

TURNTABLE

Constrained mode which forces the camera to follow meridians and parallel circles related to the up-axis.

This mode is very useful to help the user to see the up-axis of the scene vertical, i.e. parallel to the left/right borders of the screen.

TRACKBALL

Unconstrained mode which allows the camera to follow any circular orbit.

Thus, this mode allows to render the scene with any orientation.

Constructor & Destructor Documentation

SceneOrbiter::SceneOrbiter ( )

Constructor.

virtual SceneOrbiter::~SceneOrbiter ( ) [virtual]

Destructor.

Member Function Documentation

void SceneOrbiter::enableViewingCube ( bool enabled )

Enables or disables viewing cube.

Default is true.

float SceneOrbiter::getConstraintLevel ( )

Returns the current constraint level which limits the turntable rotation.

Returns:: the constraint level.

RotationMethod SceneOrbiter::getRotationMethod ( )

Returns the current scene rotation method.

openinventor::inventor::Axis::Type SceneOrbiter::getUpAxis ( )

Returns the current up axis of the scene.

SoViewingCube* SceneOrbiter::getViewingCube ( )

Returns the viewing cube object.

bool SceneOrbiter::isViewingCubeEnabled ( ) const

Returns if viewing cube is enabled.

virtual void SceneOrbiter::setCameraMode ( SceneInteractor::CameraMode mode ) [virtual]

Selects perspective or orthographic camera.

Default is perspective.

Reimplemented from SceneInteractor.

void SceneOrbiter::setConstraintLevel ( float level )

Sets the constraint level to limit the turntable rotation.

The level is a value between [0,1] used to adjust the constraint on the turntable rotation according to the speed of movement :

0 means no constraint on the rotation regardless of the interaction speed
1 means very strongly constrained even if interaction is slow.

This prevents unexpected changes in the axis of rotation during fast movements. Default is 0 which means no constraint on the rotation.

Parameters:

level

the constraint level.

void SceneOrbiter::setRotationMethod ( RotationMethod method )

Sets the scene rotation method.

Default is TURNTABLE.

void SceneOrbiter::setUpAxis ( openinventor::inventor::Axis::Type axis )

Sets the up axis of the scene.

Default is Y. Note that the up axis of the viewing cube is synchronized with the up axis of the SceneOrbiter.

The documentation for this class was generated from the following file:

Inventor/ViewerComponents/nodes/SceneOrbiter.h

SceneOrbiter Class Reference [Nodes]

Public Types