You are going to screenshot all of your work into a Powerpoint file.

To download the PowerPoint by clicking on the image below

To save your powerpoint go to:

File explorer

-> Year 9 Common Area :S

-> You can save here

-> Computer Science

-> Term 3

-> Lesson 2

Save the Powerpoint file: as your name

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Complete Task 1 in your Powerpoint

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Drawing a square:

If you remember from our last lesson in order for us to draw a square we only need the co-ordinates for the top left hand corner of the square and then the height and width in pixels. For a square the height and width should be the same.

Les's draw a square whose corner starts at (x100,y100) and whose width and height is 50px using the code below:

pygame.draw.rect(screen, green, (100,100,50,50))

Task

1. Change the x co-ordinate so that we are at the edge of the screen
2. Change the width and height so that it is 25px

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When you are finished screenshot your working code into your Learning Journal

Redrawing our square

If we want our square to move accross our screen we have to do two things:

1. Change the x co-ordinate value.
2. Redraw the square

If we want to redraw our square each time we need to make the x co-ordinate a variable.

Activity

How can we keep increasing the value of our variable xposition so that it gets bigger each time we go through our while loop?

We could create another variable called squarespeed and make it equal to say 4 and then add it to our variable xposition

Let's try it

Task: Redrawing a square

1. 
2. 

Does it look like this when you run it?

Task: Removing the old image

When we want to keep drawing something in pygame we need to clear the old image away we can do that using our screen variable and the .fill() function

Add this code to the line above where you draw your square.

screen.fill(black)

Now run your code again

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When you are finished screenshot your working code into your Learning Journal

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Can you change the speed of the square?

Can you change the direction of the square?

Can you stop it disappearing off of the edge of the screen?

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When you are done screenshot your working code into your Learning Journal

Finding the edges of the screen

When our square gets to the edge of our screen it disappears. This is not much use to us in a game.

Lets try and first work out where the edge of the screen is and then maybe reset our position so that we go back to the start.

We know the screen width because we create it with this line of code

SCREENWIDTH = 640 # sets the width of the screen/window

So in our code we could check if our xposition was greater or equal to our SCREENWIDTH and if it was reset it to 0

if xposition >= SCREENWIDTH:
   xposition = 0

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Can you make the square go backwards when it gets to the edge of the screen?

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When you are finished screenshot your working code into your Learning Journal

We want the square to not only stay on the screen but to bounce off either edge. To do that we need to check the two different x-cordinates at either side of the screen.

We have already done this once. Rather than reset our xposition to 0, what about if we made our block move backwards?

We could do that by making the value of squareSpeed a negative number.

Task

1. Change the value of squareSpeed to a negative number whenever our x-cordinate is greater than the SREENWIDTH.
2. Change the value of squareSpeed back to a positive number whenever our x-cordinate is less than 0.

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When you are finished screenshot your working code into your Learning Journal

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Summing it all up

Lets look at the learning outcomes and decide which one best describes our current level of understanding :

Tick the one you feel is closest to your level