Using FermatsPond

Like other applets in the Lite Applet Collection this applet may be used without restriction. All the necessary files and instructions are included here. This applet is written to give you the ability to change some of its features without knowing Java. Some of the variations are listed below. You should experiment a bit with these five variations to see how this applet can be customized for different uses.

• Click here to open a new window showing Fermat's Pond with all its features turned on.
  
  
• Click here to open a new window showing Fermat's Pond with reflection but not refraction.
  
  
• Click here to open a new window showing Fermat's Pond with refraction but not reflection.
  
  
• Click here to open a new window showing Fermat's Pond without the ability to list angles.
  
  
• Click here to open a new window showing Fermat's Pond without the ability to go underwater.

Now click here to open a new window showing Fermat's Pond with all its features turned on. Next choose   View --> Source   from your browser menu. You should see the html code shown below as part of the html code for the page you just opened in the new window. This is the code that includes the Fermat's Pond Java applet in a Web page.

If you want to use this applet as is in your own Web page all you need to do is three things.

• Click here to download and save a .zip file with all the files you need. Unzip the downloaded file. The result should be a directory -- FermatsPondFiles -- with the following files.
  
  
  • DataDisplayFrame.class
  • FermatsPond.class
  • fisherman.gif
  • full-featured.html

  Double click the file full-featured.html to make sure that the download and unzipping were successful. You should see the Fermat's Pond applet.

• Include the code shown above in your html file. You can copy this code from the file full-featured.html or from the View --> Source window for the full-featured page.
  
  
• Copy the files FermatsPond.class, DataDisplayFrame.class, and fisherman.gif into the same directory as your html file.

Like other applets in the Lite Applet collection, the behavior of FermatsPond can be changed without knowing Java. You can substitute a different image for the fisherman; you change the size of the applet; you can limit how students can use the applet; and you can simplify it.

• As shown above, this applet shows both the reflected image and the refracted image -- the refracted image is four times as distinct as the reflected image. To change the weights of the various images, change the values of the following parameters.
  
  
  
  • airReflectionWeight -- this parameter controls the relative weight of the image of the part of the fisherman above the water that is reflected by the water's surface. It comes into play when the observer is above the water's surface.
    
    
  • airRefractionWeight -- this parameter controls the relative weight of the image of the part of the fisherman below the waterline that is refracted by the water's surface. It comes into play when the observer is above the water's surface.
    
    
  • waterReflectionWeight -- this parameter controls the relative weight of the image of the part of the fisherman below the water that is reflected by the water's surface. It comes into play when the observer is below the water's surface.
    
    
  • waterRefractionWeight -- this parameter controls the relative weight of the image of the part of the fisherman above the waterline that is refracted by the water's surface. It comes into play when the observer is below the water's surface.

  These parameters enable you to customize this applet so that it shows only reflection or only refraction. See the reflection only example and the refraction only example and choose View-->Source. If you substitute your own picture of a fisherman then you may want to adjust the relative weights of the reflected and refracted images.
  
  

• One way to use this applet is by challenging students to determine how the fisherman appears to a fish. There is a bit of a surprise -- to a fish, the fisherman sometimes appears to be cut in half. You can see this phenomenon by clicking at various points below the water's surface. If you want students to discover this for themselves using a bit of physics and mathematics, you can change the value of the parameter divemask to 0. With this value the rightmost panel goes gray when the user clicks below the water's surface.
  
  
• To hide the List Angles button change the value of the userDisplaySw parameter to 0.
  
  
• You can substitute your own picture of a fisherman for the picture used here. This requires changing several parameters.
  
  
  • Change the value of the filename parameter to the name of your new image. Note you are responsible for adding the water to your image. The RGB values for the water's color are -- (192, 224, 255).
    
    
  • Change the value of the imageWidth and imageHeight parameters to the width and height of your new image.
    
    
  • Change the value of the height parameter in the applet tag to the image height + 20.
    
    
  • Change the value of the width parameter in the applet tag to the image width + 2 * the image height.
    
    
  • Change the value of the waterline parameter to the y-coordinate (in pixels from the bottom) of the waterline in your new image.