Alice Tutorials: Camera Control
In the scene setup editor, three sets of navigation controls (sets of arrows) can be used to move the camera. These navigation controls are very helpful for achieving better camera views for meticulous object placement in an initial scene and for positioning the camera in a new location or at a different angle.
1. Left Most Control - Moves the camera vertically and horizontally.
2. Central Control - Moves the camera forward and backward or pans left and right.
3. Right Most Control - Tilts the camera.
In Alice, a dummy is an invisible 3D-axes object, used to mark the location and orientation of the camera. A dummy may be accessed either (a) during scene setup or (b) during the running of an animation (at runtime).
Why would you want to use a dummy marker? The main reason is a dummy marker allows Alice to remember the original camera position -- so the camera can be returned to that position before saving a world as the initial scene for your animation. Another good reason is that several dummy markers may be used to allow Alice to remember several different camera locations for multiple views of the same scene or for views of different scenes in the same world.
In this section of the tutorial, we first look at how to drop a dummy marker and then how to access the dummy marker for scene setup and at runtime.
To drop a dummy marker, follow these steps:
1. In the scene editor, click on the More controls button (right hand side)
2. Click on the Drop Dummy at Camera button
3. (Optional, but very useful!) If you wish to rename the dummy object, go into the Object Tree, click on the '+' to the left of the Dummy object's folder, and then right mouse click on the Dummy object to rename to a more meaningful name, such as originalPosition.
Using a Dummy Marker for Scene Setup
A common use of a dummy marker is to remember the original camera position for the purpose of returning the camera to this position prior to saving the initial scene for animation. This can be done easily if a dummy marker has been dropped at the original camera location (before moving the camera during scene setup).
This is a scene in which the camera has been moved back away from the castle.
To return the camera to its original position, pull down the menu for the move camera to dummy button and select the originalPosition (or Dummy) dummy marker, as shown here.
Now, the camera is returned to its original position.
Using a Dummy Marker at Runtime
If a dummy marker for a camera position was dropped during scene setup, the camera can be repositioned to any such dummy marker at runtime. To move the camera to a marked position, invoke the camera's set point of view method and choose "name-of-dummy" as the target object, where "name-of-dummy" is the name of the dummy object. (View the point of view instruction description, example code, and a movie of the world in action.)
The following images show motion of the camera at runtime to various marked positions:
This image shows the result of setting the camera point of view to a marker at the left side of the scene.
This image shows the result of setting the camera point of view to a marker at the right side of the scene..
