starry_starry_night_ec.py (20 points)

Draw some stars!

Requirements

Instructions

• Only parts 4 and 5 will be graded
• Parts 1 through 3 will help incrementally build 4 and 5
  • you should still do them
  • (but you may comment out / remove some parts that are no longer relevant)
• Partial credit will be given
• The last two parts have different point values
  • Part 4 is 15 points
  • Part 5 is 5 points (and it's more challenging than part 4)

Part 1

• customize the colors of your drawing (choose whatever colors you like)
  • change the background color
  • set the pen color
• turn animation off (we're going to be drawing a lot of stars)
• set the width and height to 800 width and 600 height
• create a function called draw star
  • you can draw whatever star you like
  • the examples show a typical 5 pointed star
  • parameters: x, y and size
  • processing: it will draw a star at the x and y location specified, and the size of the star; you can take that to mean the size of a side (easier), or the entire star
  • return: does not return anything
  • don't forget to call update at the end of it
• call your function once to draw a star in the middle of the screen

Part 2

• comment out your function call for drawing a single star from the previous part
• now, instead of drawing a single star, draw several stars using a for loop
• they can be drawn in a straight line horizontally or vertically
• or… if you want to get fancy, draw them in a curve
• see the examples below:

Part 3

• again, comment out your code for drawing several stars from the previous part
• now, create another function called generate_star_data
  • this function will generate a list of lists that represents star data:
    • the first element in the sub list will represent an x value, the second represents a y value, and the last represents size
    • for example, [[0, 0, 10], [200, 200, 80]] represents 2 stars, one at the origin… and a larger star on the upper right hand corner
  • parameters: an int that represents the number of elements in the list (the number stars / sub lists)
  • processing:
    • it will randomly generate x, y, and size values, put these values into a list…
    • and add this three element list to the star list (the list of lists)
    • the bounds of the random numbers that you generate can be hard coded based on the width and height of the window
  • return: the list of lists representing stars
• example usage below:

star_data = generate_star_data(2)
print(star_data)
#  prints out: [[-250, 121, 49], [100, 0, 20]] 

Part 4 (15 points)

• use the function from the previous part to generate a list of 40 stars (a list of 40 sub lists)
• save the result of this into a global variable (that is, it should be a variable defined outside of all of your functions)
• create a function called draw_sky:
  • within it, iterate through the global list you created
  • draw a star based on the data in the sub list (x, y and size)
• call you draw_sky function once…
• it should look something like this:

Part 5 (5 points)

Make the following modifications to part 4

• within your draw sky function, increment the x value of every sub list by 1 as you iterate through the sub lists to draw stars
• instead of calling your draw_sky function once, use ontimer to have you draw_sky function call itself again in 30 ms
  • call ontimer at the end of your draw_sky function
  • with draw_sky as the first argument (no quotes), and 30 as the second
• you should see an animation!
• now… change your generate_star_data function so that the sub list that creates also contains a 4th value
  • this value represents a velocity
  • it should be small (maybe between 1 and 5)
• in your draw_sky function, as you iterate through your list of star data, add the generated velocity (the value at index 3) to the x value (the value at index 0) rather than just increment by 1