Fractal image generator

This is the documentation for the Web app used in Lesson plan #10 of the Plato’s Playground collection of projects developed for elementary school-age children. For technical reasons, the fractal image generator can only be run on a computer, rather than a phone or tablet.

This app will let you display and blow up portions of the Mandelbrot app, navigate quickly between blowups, change color palettes, generate Julia sets and save and restore the images you create to files on your computer. 

To launch the app, navigate to the URL https://app.platosplayground.org. The following will be displayed on your computer screen:

If necessary, scroll down using the thumbwheel on your mouse to reveal the app controls:

Here’s what the controls do:

• Back: Display the previous image following a blowup.

• Forward: Display the next image, if any.

• Color palette: The color palette control is a dropdown menu that allows you to select different pre-built color palettes. Once a palette is selected, the image on the screen will be colored accordingly.

• Mandelbrot/Julia: Switch fractal modes. When set to Julia, left-click on a point within the Mandelbrot set and then right-click to generate the Julia set for that point.

• Zoom: When in Mandelbrot mode, tap anywhere outside the Mandelbrot set to identify the start of the region to blow up, then drag the mouse down and to the right to define the end of the region. This will create a red square. Release the left mouse button and press the right button to begin drawing. To cancel the blowup and erase the red square, click the Cancel selection button located at the upper left-hand corner of the screen.

• Open...: When active, pressing the button will display a list of images you had saved to local storage. Double-click an image in the list or select an image and press the Open button.

• Save...: Enter the name you want to give to the image and either press the Enter key on your computer or press the Save button to copy the image to local storage.

• Detail level: This control (default 50) enables you to determine the trade-off between image computation time versus image detail. The higher the number, the more detail you will get when you blow up regions outside the Mandelbrot set, but the longer it will take for the app to display the blowup.

• Export...: Pressing this button will download to your computer the current fractal image as a .img file. Later, you may upload the file for display and/or modification via the Import... button.

• Import...: Read and display a native .img file from your computer. These are fractals that contain certain control information that allow them to be modified (blown up, change color, etc.). There are several .img files available for free online at Importing images.

• Help: Display this Help screen.