Tutorial 16: Circles
Drawing Circles on the Graph Screen...
HOME >> Tutorials >> Tutorial 16: Circles

Introduction:
Unlike lines, there is no easy way to make a circle without using the command that draws a circle. In this tutorial there will not be many sets of code because there aren't many ways to use a circle without making a picture and using other commands like lines, pixels, and points. This tutorial only has one command:

New Commands:

Circle( Draws a circle with the center at (x,y) and a radius

Circle(X,Y,radius)

The Codes:
There are only going to be two codes this time. The first will show you how to draw circles inside of other circles and the second will draw the Olympics 5-ring symbol.

: For AShell, SOS, and TI-Explorer
AxesOff Turns the graph axes off
FnOff Deselects all the Y= functions
0STOREXmin Stores Xmin as 0
94STOREXmax Stores Xmax as 94
0STOREYmax Stores Ymax as 0
-62STOREYmin Stores Ymin as -62
ClrDraw Clears the graph screen of all drawings
Circle(47,-31,30 Draws a circle centered at (47,-31) and radius of 30
Circle(47,-31,5 Draws a circle centered at (47,-31) and radius of 5
Circle(47,-31,25 Draws a circle centered at (47,-31) and radius of 25
Circle(47,-31,10 Draws a circle centered at (47,-31) and radius of 10
Circle(47,-31,20 Draws a circle centered at (47,-31) and radius of 20
Circle(47,-31,15 Draws a circle centered at (47,-31) and radius of 15
Pause Suspends program and waits for user to press ENTER
ClrDraw Clears the graph screen of all drawings
For(X,5,30,5 X stored from 5-30 with increments of 5
Circle(47,-31,X Draws a circle at (47,-31) and radius of X value
End End the For loop

press ENTER

As you may have already noticed, this program takes a long time to finish because it draws the circles so slowly, but there's nothing we can do about that. Notice how the same thing is displayed before and after the Pause. You can do it both ways, but in this case, I would prefer to do it the second way because it saves space. Neither way makes the program any faster, but the second way saves the bytes. Next, we'll make the Olympics logo.

: For AShell, SOS, and TI-Explorer
AxesOff Turns the graph axes off
FnOff Deselects all the Y= functions
0STOREXmin Stores Xmin as 0
94STOREXmax Stores Xmax as 94
0STOREYmax Stores Ymax as 0
-62STOREYmin Stores Ymin as -62
ClrDraw Clears the graph screen of all drawings
Circle(15,-15,12 Draws a circle centered at (15,-15) and radius of 12
Circle(30,-30,12 Draws a circle centered at (30,-30) and radius of 12
Circle(45,-15,12 Draws a circle centered at (45,-15) and radius of 12
Circle(60,-30,12 Draws a circle centered at (60,-30) and radius of 12
Circle(75,-15,12 Draws a circle centered at (75,-15) and radius of 12

Pretty cool, huh? It actually came out pretty nice. It took a couple of trials and error to get it exactly right (at first I had a radius of 20 and then a radius of 15), but I finally got it.

Conclusion:
I think that should be enough for you to grasp how to use Circle(. I can't really think of any other ways to show you how to use it. I was going to show you how to make a coke can, but I'm leaving that for the tutorial on draw functions. The next tutorial is on shading, which is the final step in making good pictures.

If you do not understand a particular part in this lesson, have suggestions, or find any problems please contact me.

Previous Tutorial Next Tutorial
Tutorial 15 Tutorial 17





Problems with this page?
Contact the Webmaster.