All Packages Class Hierarchy This Package Previous Next Index
java.lang.Object
|
+----dnx.util.DNXObject
|
+----dnx.lr.Node
|
+----dnx.lr.LeafNode
|
+----dnx.lr.BindableNode
|
+----dnx.lr.node.NavigationInfoNode
NavigationInfo {
eventIn SFBool set_bind
exposedField MFFloat avatarSize [ 0.25, 1.6, 0.75 ]
exposedField SFBool headlight TRUE
exposedField SFFloat speed 1.0
exposedField MFString type "WALK"
exposedField SFFloat visibilityLimit 0.0
eventOut SFBool isBound
}
The NavigationInfo node contains information describing the physical characteristics of the viewer and viewing model. NavigationInfo is a bindable node (see "Concepts - Bindable Children Nodes") and thus there exists a NavigationInfo stack in the browser in which the top-most NavigationInfo on the stack is the currently active NavigationInfo. The current NavigationInfo is considered to be a child of the current Viewpoint - regardless of where it is initially located in the file. Whenever the current Viewpoint changes, the current NavigationInfo must be re-parented to it. Whenever the current NavigationInfo changes, the new NavigationInfo must be re-parented to the current Viewpoint.
If a TRUE value is sent to the set_bind eventIn of a NavigationInfo, it is pushed onto the NavigationInfo stack and activated. When a NavigationInfo is bound, the browser uses the fields of the NavigationInfo to set the navigation controls of its user interface and the NavigationInfo is conceptually re-parented under the currently bound Viewpoint. All subsequent scaling changes to the current Viewpoint's coordinate system automatically change aspects (see below) of the NavigationInfo values used in the browser (e.g. scale changes to any parent transformation). A FALSE value of set_bind, pops the NavigationInfo from the stack, results in an isBound FALSE event, and pops to the next entry in the stack which must be re-parented to the current Viewpoint. See "Concepts - Bindable Children Nodes" for more details on the the binding stacks.
The type field specifies a navigation paradigm to use. Minimally, browsers shall support the following navigation types: "WALK", "EXAMINE", "FLY", and "NONE". Walk navigation is used for exploring a virtual world. It is recommended that the browser should support a notion of gravity in walk mode. Fly navigation is similar to walk except that no notion of gravity should be enforced. There should still be some notion of "up" however. Examine navigation is typically used to view individual objects and often includes (but does not require) the ability to spin the object and move it closer or further away. The "none" choice removes all navigation controls - the user navigates using only controls provided in the scene, such as guided tours. Also allowed are browser specific navigation types. These should include a unique suffix (e.g. _sgi.com) to prevent conflicts. The type field is multi-valued so that authors can specify fallbacks in case a browser does not understand a given type. If none of the types are recognized by the browser, then the default "WALK" is used. These strings values are case sensitive ("walk" is not equal to "WALK").
The speed is the rate at which the viewer travels through a scene in meters per second. Since viewers may provide mechanisms to travel faster or slower, this should be the default or average speed of the viewer. If the NavigationInfo type is EXAMINE, speed should affect panning and dollying--it should have no effect on the rotation speed. The transformation hierarchy of the currently bound Viewpoint (see above) scales the speed - translations and rotations have no effect on speed. Speed must be >= 0.0 - where 0.0 specifies a stationary avatar.
The avatarSize field specifies the user's physical dimensions in the world for the purpose of collision detection and terrain following. It is a multi-value field to allow several dimensions to be specified. The first value should be the allowable distance between the user's position and any collision geometry (as specified by Collision) before a collision is detected. The second should be the height above the terrain the viewer should be maintained. The third should be the height of the tallest object over which the viewer can "step". This allows staircases to be built with dimensions that can be ascended by all browsers. Additional values are browser dependent and all values may be ignored, but if a browser interprets these values the first 3 should be interpreted as described above. The transformation hierarchy of the currently bound Viewpoint scales the avatarSize - translations and rotations have no effect on avatarSize.
For purposes of terrain following the browser needs a notion of the down direction (down vector), since gravity is applied in the direction of the down vector. This down vector should be along the negative Y-axis in the local coordinate system of the currently bound Viewpoint (i.e., the accumulation of the Viewpoint's parent transformations, not including the Viewpoint's orientation field).
The visibilityLimit field sets the furthest distance the user is able to see. The browser may clip all objects beyond this limit, fade them into the background or ignore this field. A value of 0.0 (the default) indicates an infinite visibility limit. VisibilityLimit is restricted to be >= 0.0.
The speed, avatarSize and visibilityLimit values are all scaled by the transformation being applied to currently bound Viewpoint. If there is no currently bound Viewpoint, they are interpreted in the world coordinate system. This allows these values to be automatically adjusted when binding to a Viewpoint that has a scaling transformation applied to it without requiring a new NavigationInfo node to be bound as well. If the scale applied to the Viewpoint is non-uniform the behavior is undefined.
The headlight field specifies whether a browser should turn a headlight on. A headlight is a directional light that always points in the direction the user is looking. Setting this field to TRUE allows the browser to provide a headlight, possibly with user interface controls to turn it on and off. Scenes that enlist pre-computed lighting (e.g. radiosity solutions) can turn the headlight off. The headlight shall have intensity = 1, color = 1 1 1, ambientIntensity = 0.0, and direction = 0 0 -1.
It is recommended that the near clipping plane should be set to one-half of the collision radius as specified in the avatarSize field. This recommendation may be ignored by the browser, but setting the near plane to this value prevents excessive clipping of objects just above the collision volume and provides a region inside the collision volume for content authors to include geometry that should remain fixed relative to the viewer, such as icons or a heads-up display, but that should not be occluded by geometry outside of the collision volume.
The first NavigationInfo node found during reading of the world is automatically bound (receives a set_bind TRUE event) and supplies the initial navigation parameters.
avatarSize
headlight
isBound
speed
type
visibilityLimit
NavigationInfoNode()
createNodeDefinition(NodeDefinition)
handleEvent(SceneEvent)
initFields()
postIsBoundEvent()
postIsUnboundEvent()
avatarSize
public MFFloat avatarSize
headlight
public SFBool headlight
speed
public SFFloat speed
type
public MFString type
visibilityLimit
public SFFloat visibilityLimit
isBound
public SFBool isBound
NavigationInfoNode
public NavigationInfoNode()
createNodeDefinition
protected void createNodeDefinition(NodeDefinition def)
initFields
protected void initFields()
handleEvent
protected void handleEvent(SceneEvent ev)
postIsBoundEvent
public void postIsBoundEvent()
postIsUnboundEvent
public void postIsUnboundEvent()
All Packages Class Hierarchy This Package Previous Next Index