Plan du cours :

• open then close a window in which stimuly will appear
• draw something in that window
• draw basic shapes
• modify the position of a stimulus
• modify the color of a stimulus
• control the timing

If we have time

• show an image in the window
• show some texte in the window

Open and close a window

1. Open a terminal and launch an ipython interpreter

2. type the following command to get access to the pygame module and all its amazing possibilities

   import pygame

3. Then you have to initialize all the things that pygame requires

   pygame.init()

4. Nothing shows up yet, and that’s normal. In order to be able to draw something you have to define a display window, which requires us to specify the width and height of the window

   pygame.display.set_mode((400,300))

5. Now you can close your window

   pygame.quit()

6. You might notice that there is still some pygame stuff running, so to actually close everything, quit the interpreter

   quit

Exercise

1. Try again, but this time, Use a variable to store the display window object

   MY_WINDOW=pygame.display.set_mode((400,300))

2. Take a look at the variable attributes and methods using

   MY_WINDOW. and hit the tabulation key

Basic Pygame program

1. From the template Louis presented, make a little program with the commandes you just typed in the ipython interpreter
2. Save that program with an appropriate name

3. run it using the command line

   python name_of_your_program.py

Exercise

1. What do you notice?
2. Open a ipython interpreter to get access to the nice built-in help
3. Try to understand what does the pygame.time.wait function and use it in your program
4. Now, modify your program to display a window with different dimensions
5. Let’s take a look together at the program prems.py

Change the background color of the window

Now we will interact a little bit with that display window.

Color code

The colors are coded using a triplet of values for its RED, GREEN and BLUE components.
Each component intensity is represented by a number that can take values between 0 and 255 (it is coded on one 8-bit byte).
Thus:

• RED is coded as (255,0,0)
  
• GREEN is coded as (0,255,0)
• BLUE is coded as (0,0,255)
• BLACK is coded as (0,0,0)
• WHITE is coded as (255,255,255)

A little explanation on display asynchrony

In order to control the timing of a stimulus appearance on a screen, drawing and displaying are two diferent steps.

1. you prepare a stimumus in the graphic memory of the video card of your computer using pygame functions
2. you tell the computer to show on the screen what you prepared with the pygame.display.flip() function

Exercice

1. make a nex program from prems.py
2. use the MY_WINDOW.fill() method to change the color of the window
3. use pygame.display.flip() to actually display it