Navigation component

This component defines nodes to control the camera, and some effects closely related to the camera. NavigationInfo controls the camera behavior. Viewpoint and OrthoViewpoint define the initial camera position and rotation, and may be used to animate the camera. LOD allows to implement level-of-detail, where different versions of 3D scene are displayed depending on the camera distance. Collision allows to use a simpler geometry for collision purposes, or even to turn the collisions off (like a fake walls hiding secret rooms in games). Billboard may be used to create sprites, as it aligns geometry (flat or not) with respect to the camera.

See also X3D specification of the Navigation component.

Contents:

See also Castle Game Engine (and view3dscene) extensions related to navigation.

1. Demos

For demos and tests of these features, see the navigation subdirectory inside our VRML/X3D demo models.

2. Supported nodes

  • Viewpoint (API reference),
    OrthoViewpoint (API reference).

    Supported.

    view3dscene displays a nice menu allowing you to jump to any defined viewpoint, showing viewpoints' descriptions. Animating viewpoint's position and orientation (directly or by animating it's parent transformation) also works perfectly.

    TODO: fields not implemented yet: jump, retainUserOffsets, centerOfRotation.

    • Support for centerOfRotation already exists in the engine (TExamineCamera.CenterOfRotation), so it should be easy to finish it (copy X3D Viewpoint.centerOfRotation to TExamineCamera.CenterOfRotation). But we may have to treat centerOfRotation = 0,0,0 as special value meaning "middle of the box", otherwise many models will have weird navigation because they lack correct centerOfRotation value (and the default is just zero).

      Suggestions and reports how does this work in other VRML/X3D browsers are welcome.

    • Support for jump and retainUserOffsets is probably easy, but someone has to actually understand the X3D specification about them, and explain how they are related to each other (and to NavigationInfo.transitionType). Suggestions and testcases and reports how do they work in other VRML/X3D browsers are welcome.

  • NavigationInfo (API reference)

    Supported.

    • avatarSize is honoured fully:

      1. First avatarSize item is the camera radius. If you use view3dscene, note that --camera-radius command-line option overrides this value.

      2. 2nd avatarSize item is the preferred height above the ground.

      3. 3rd avatarSize item is the tallest object over which you can climb.

        If this is missing (or it has value <= 0) then there's no such limit, and you can climb as long as you can move forward. So you can climb the stairs with steps almost as high as your own height minus the camera radius. Simplifying (ignoring other effects, like head bobbing), you can say that avatarSize[2] is by default like avatarSize[1] - avatarSize[0]).

        See TWalkCamera.ClimbHeight API docs for more details about this.

    • speed field is supported, it sets the speed in meters/second. Speed = 0.0 is also correctly honored (user will not be able to move in Walk/Fly modes, only to rotate).

    • type field is supported. Navigation types fully supported are: EXAMINE, WALK, FLY, NONE. Inside the engine, the navigation paradigm is actually a little more flexible. You can fine-tune the rotations and gravity behavior by view3dscene Navigation -> Walk and Fly Settings menu.

      As an extension, we also support new navigation mode TURNTABLE. This is similar to the Examine mode, with controls comfortable for viewing models that have a sense of floor/ground in the XZ plane, and vertical axis in +Y. Implementation is not finished yet.

      The presence of navigation type ANY is ignored by view3dscene. We always show controls to change navigation settings, hiding them feels harmful to user.

    • Nice transitions between viewpoints are supported, honouring transitionType and transitionTime fields, and (since view3dscene 3.13.0) making transitionComplete event. See demo model navigation/transition_multiple_viewpoints.x3dv showing how to use it to make an animated transition between a couple of viewpoints.

    Binding different NavigationInfo nodes, and changing their exposed fields by events, of course works.

    When no NavigationInfo node is present in the scene:

    • avatarSize and speed are calculated based on scene's bounding box sizes, to a values that will hopefully "feel right". We try to calculate them intelligently, because simply using NavigationInfo defaults results in bad experience in many scenes.
    • headlight behaves like true, type behaves like [EXAMINE, ANY], this follows NavigationInfo defaults.

    TODO: visibilityLimit may be ignored if shadow volumes are allowed (We use frustum with z-far in infinity then.)

  • LOD (API reference)

    Note: We do not have any automatic LOD calculation implemented now, which means that your supplied range, and only your supplied range, controls which LOD is chosen. This means that forceTransitions value is simply ignored, and when range is empty, we simply always use the first (highest-detail) version. This is Ok, spec allows this.

  • Billboard (API reference)

    Works fully.

  • Collision (API reference)

    Most things work: grouping (children property, in particular), allows to control collision detection by honoring enabled (named collide in VRML 97) and proxy fields.

    bboxCenter/Size is currently simply ignored, our engine always calculates and updates the bounding boxes where needed.

    TODO: collideTime and isActive out events are not implemented yet.

  • ViewpointGroup (API reference)

    You can use them to create submenus in "Viewpoints" menu in view3dscene: description and children work. Also, you can use this to hide some viewpoints from the menu: displayed field works.

    TODO: size/center is not honored yet. Group is displayed regardless of camera position. A possible workarond could be to use a ProximitySensor node, routing ProximitySensor.isActive to the displayed field... Except this workaround will not work too, because changing of the displayed field after the scene loading doesn't change the menu for now.

    TODO: retainUserOffsets is ignored.