Tutorial Home / Complex Interactions / Creating Switch Nodes

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Overview

A Switch is a special grouping node in VRML which allows you to switch between between a number of objects or groups of objects. A Switch node is activated when it receives an integer from a script into its whichChoice field. So if it receives the number 3 it will display the 4th child object or group of objects (numbering starts from 0).

Switches are most often used for turning things on and off or switching between a number of alternatives eg. a user could click a sofa to see how different designs look in a living room.

In this exercise we will be using switches for the flash texture and the LCD screen on the back of the camera. In the scripting exercise to follow we will connect the necessary routes to make these switches operate.

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Required Files

Download and unzip the following file (using WinZip) into the relevant folder of your working directory.

camera_sensored.zip (47Kb)

This file contains:

all_textures.zip (158Kb)

This file contains:

  • battery.png*
  • camera.png*
  • flash.png
  • icon1.png*
  • icon2.png*
  • icon3.png*
  • icon4.png*
  • lcd_image_record.jpg
  • lcd_mpeg_record.jpg
  • lcd_playback.jpg
  • lcd_startup.jpg
  • lens.jpg*
  • logos.png*
  • memory_stick.png*
* indicates this texture not used in this part of the tutorial.

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Tutorial

Launch Cosmo Worlds and Open the file camera_sensored.wrl
Ensure Interactive Paste Placement is off (remove the tick if necessary).
Select the LCD screen on the back of the camera and name it screen1.

+ C to copy it then + V three times so that we end up with a total of 4 LCD screens in the same place.

Name the copies screen2, screen3 and blankScreen. Select each of the screens in turn and apply a different LCD texture to each. On the last screen named blankScreen remove the texture altogether.
Select all 4 screens in the Outline Editor and click the Switch node grouping icon
Drill-down into the whichChoice field and change the value to 0 (this is our default value - screen1).

Now for the flash.

Create a new face above the camera, scale and position it as shown. It should be resting just in front of the flash. Apply the texture flash.png to the face.

Create a Switch around the flash object and change the whichChoice field to 1.

This makes the flash invisible by default and the control script will simply toggle briefly to 0 to display the flash.
The last thing we need to do is move this newly created object up the scene graph until it is in the lens group, otherwise rotating the lens will result in the flash being left behind.
Note: neither of the 2 switches we have set up will do anything until the control script is wired up.  
Save your work.  
Preview in Cosmo Player.  

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