Program 6 - Snowflakes and Other Drawings

This program has two parts, one fixed and one allowing for some creativity.

For the fixed part, take the program we wrote in class and modify it in two ways.

• Notice that every arm of the snowflake has two symmetrical sides. The block under the "for i in range(6):" statement is of course run six times, once for each arm. An arm consists of six lines, each one drawin by a call to circleSegment(). The six lines are divided into three groups; each group draws a line an its mirror image. You can try commenting out each of the circleSegment() calls, one at a time, to get a sense of which function call is drawing which line.

  Add a function drawBothLines() that draws a line and its mirror image. And change the program so that instead of calling circleSegment() six times in the block under the for loop, it calls drawBothLines() three times.

  So drawBothLines() should draw two line segments instead of one, and it will need to figure out two points for each segment, for a total of four points. So it will have four calls to pointOnCircle(), and two calls to gr.line().

  What parameters does drawBothLines() require? What arguments should be used when calling drawBothLines()? Does it need a return value? Does it use a global variable? Think about these questions before you start typing.

• Make the program draw three smaller snowflakes instead of one big one. Put them in three different places in the picture.

Now for the more creative part. After the user closes the window containing the snowflakes, your program should open another window showing a drawing of your choice. Your drawing should include many copies of some object (like the snowflake picture does). For instance, a 3x3 grid of snowmen or of abstract pine trees would be fine. Your program should use a loop, calling a function. For instance, to get a 3x3 grid of snowmen, you would have a loop that runs three times (for the rows), containing another loop that runs three times (three snowmen per row), calling a function that draws a snowman. More snowflakes would be OK, if you do something to make them more interesting. For instance, make every snowflake different by using random.randrange() to help your program pick where to draw lines.

For the crazy ambitious, you could do something more elaborate. One idea would be to look up "Koch snowflake" on Wikipedia, and try to get that idea working with our graphics module (notice the example there is using the Python turtle module, which is an even more primitive graphics module than ours).