Game set up in Pygame + Character Creation, Movement and Coordinate detection (tracking)

First things first - you need to set up your game and get a character on the screen. The following code and presentation show you how to get started, create a character, and also track the player's movement on the scren by printing the coordinates to the screen. This will help you understand the computer's coordinate system better, and it is integral to being able to work with collision detection and other more complex concepts later.

Video Demo

Explanation

Code

import pygame
 
# Define some colors
BLACK = (0, 0, 0)
WHITE = (255, 255, 255)
GREEN = (0, 255, 0)
RED = (255, 0, 0)

#Set the max speed the player can move - changing this value can increase/decrease difficulty
PLAYER_SPEED = 5

#This function draws the smaller user-controllable stick figure on the screen
def draw_stick_figure(screen, x, y):
    # Head
    pygame.draw.ellipse(screen, BLACK, [1 + x, y, 10, 10], 0)
    print(x,y)

 
    # Legs
    #Right leg (colour, length of leg....)
    pygame.draw.line(screen, BLACK, [5 + x, 17 + y], [10 + x, 27 + y], 2)
    #Left Leg
    pygame.draw.line(screen, BLACK, [5 + x, 17 + y], [x, 27 + y], 2)
 
    # Body
    pygame.draw.line(screen, RED, [5 + x, 17 + y], [5 + x, 7 + y], 2)
 
    # Arms
    pygame.draw.line(screen, RED, [5 + x, 7 + y], [9 + x, 17 + y], 2)
    pygame.draw.line(screen, RED, [5 + x, 7 + y], [1 + x, 17 + y], 2)

#This function ensures that the number entered is between the range of the min and max values (inclusive). 
#If the number is outside of this range, we return the closest allowed value. I.e. if the max was 10 and the number
#entered was 12, 10 would be returned as this is the maximum value allowed
def keep_in_range(number, min_no, max_no):
    if (number < min_no):
        return min_no
    elif (number > max_no):
        return max_no
    else:
        return number
# Setup
pygame.init()
 
# Set the width and height of the screen [width,height]

screen_size = [700, 500]
screen = pygame.display.set_mode(screen_size)
 
pygame.display.set_caption("My Game")
 
# Loop until the user clicks the close button.
done = False
 
# Used to manage how fast the screen updates
clock = pygame.time.Clock()
 
# Hide the mouse cursor
pygame.mouse.set_visible(0)
 
# Speed in pixels per frame
x_speed = 0
y_speed = 0

# Current position
x_coord = 300
y_coord = 1
 
# -------- Main Program Loop -----------
while not done:
    # --- Event Processing
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            done = True
            # User pressed down on a key
 
        elif event.type == pygame.KEYDOWN:
            # Figure out if it was an arrow key. If so
            # adjust speed.
            if event.key == pygame.K_LEFT:
                x_speed = -PLAYER_SPEED
            elif event.key == pygame.K_RIGHT:
                x_speed = PLAYER_SPEED
            elif event.key == pygame.K_UP:
                y_speed = -PLAYER_SPEED
            elif event.key == pygame.K_DOWN:
                y_speed = PLAYER_SPEED
 
        # User let up on a key
        elif event.type == pygame.KEYUP:
            # If it is an arrow key, reset vector back to zero
            if event.key == pygame.K_LEFT or event.key == pygame.K_RIGHT:
                x_speed = 0
            elif event.key == pygame.K_UP or event.key == pygame.K_DOWN:
                y_speed = 0
 
    # --- Game Logic
 
    # Move the object according to the speed vector.
    x_coord = x_coord + x_speed
    y_coord = y_coord + y_speed

    if (x_coord < 0):
        x_coord = 0

    if (y_coord < 0):
        y_coord = 0

    #Adjust the x and y co-ordinates to ensure that the stick figure is kept on the screen and can't
    #travel off of it
    x_coord = keep_in_range(x_coord, 0, screen_size[0] - 10) #We adjust the upper limit of our allowed range to match the stick figures width
    y_coord = keep_in_range(y_coord, 0, screen_size[1] - 27) #We adjust the upper limit of our allowed range to match the stick figures height
    # --- Drawing Code
 
    # First, clear the screen to WHITE. Don't put other drawing commands
    # above this, or they will be erased with this command.
    screen.fill(WHITE)
 
    draw_stick_figure(screen, x_coord, y_coord) #draw the stick figure on the screen
 
 
    # Go ahead and update the screen with what we've drawn.
    pygame.display.flip()
 
    # Limit frames per second
    clock.tick(60)
 
# Close the window and quit.
pygame.quit()