Circle and random

Before we go further, we need to stop again and learn a few things. For the next program, we'll need some new functions that we haven't seen before. Let's see them one by one.

Drawing circles

Using Pygame we can draw circles on the screen. This is the code we need to use:

pygame.draw.circle(screen, color, position, radius)

The words screen, color, position and radius are information that we'll have to provide. This is an example of use:

screen = pygame.display.set_mode([800, 600])
pygame.draw.circle(screen, [255, 255, 255], [100, 100], 10)

The code above will draw a white circle with a 10-pixel radius at the position x=100 and y=100. You will have to provide a screen similar to how we have done before. Write a program to try it out. Then try these challenges:

1. Make the circle red.
2. Draw the circle in a different position.
3. Draw a larger circle.

Generating random numbers

In Python, there are several ways of generating random numbers. Regardless of how we do it, we'll need to import the random library into our program. Then we can use a function such as the following:

random.randint(1, 10)

That code will generate a random number between 1 and 10. Here are some challenges:

1. Print the number on screen.
2. Generate a number between 100 and 200.

Putting it all together

OK, so now let's write a program that uses all the above. Write code for each one of the following steps, one by one:

1. Import the random library.
2. Import Pygame.
3. Define a class Circle.
4. Create an empty list where we'll put our circles.
5. Write a loop that will run 100 times. Each time it will do the following:
   1. Create a Circle object and put it in a variable.
   2. Give the object a random x coordinate, between 0 and 800.
   3. Give the object a random y coordinate, between 0 and 600.
   4. Give the object a random radius, between 5 and 50.
   5. Add the object to the list of circles.
6. Initialize Pygame
7. Create a window of size 800x600
8. Write a loop that, for each object in the list, does the following:
   1. Draw a white circle on the screen, with the coordinates and radius given by the object in the list
9. Update the screen.