How to use

On this site I try to pass most of the knowledge using practical examples. It’s a digital book, and unlike paper books I can make pages interactive. There will be interactive code editors on most pages. I would have loved to have these tools when I started learning programming. Try it out yourself, write any code you want and press run to see the output printed below:

python
cpp

There are currently two supported programming languages: Python and C++. In game programming C++ is the language of choice for most high quality games. This is due to the flexibility it offers to mess around with low level details such as memory management. For high level concepts I will try to use Python more, as it’s the easier language to teach and understand general concepts.

Often I feel the need to explain visually, especially when it comes to math. Learning by doing or learning by example is what taught me the best, so I will keep providing these code editors. Both for the Python and C++ there is functionality to present to a canvas. Below you’ll find a classic game example for the Python editor (note that you will have to click on the canvas to enable focus for keypresses):

python

from processing import *

def setup():
    size(width, height)

def draw():
    background(0)
    ball.update()
    ball.draw()
    for paddle in paddles:
		paddle.update()
		paddle.handleIntersect(ball)
		paddle.draw()

def keyPressed():
    if(keyboard.keyCode == 38): #Up
        paddles[1].speedY = -paddleSpeed
    if(keyboard.keyCode == 40): #Down
        paddles[1].speedY = paddleSpeed
    if(keyboard.key == 'a'):
        paddles[0].speedY = -paddleSpeed
    if(keyboard.key == 'z'):
        paddles[0].speedY = paddleSpeed

def keyReleased():
    if(keyboard.keyCode == 38): #Up
        paddles[1].speedY = 0
    if(keyboard.keyCode == 40): #Down
        paddles[1].speedY = 0
    if(keyboard.key == 'a'):
        paddles[0].speedY = 0
    if(keyboard.key == 'z'):
        paddles[0].speedY = 0

class Ball:
    def __init__(self, x, y, diameter, speedX, speedY):
        self.x = x
        self.y = y
        self.diameter = diameter
        self.speedX = speedX
        self.speedY = speedY
        self.c = 225

def update(self):
        self.y += self.speedY
        self.x += self.speedX
        if (self.right() > width or self.left() < 0):
            self.x = width / 2
            self.y = height / 2
        if (self.bottom() > height or self.top() < 0):
            self.speedY = -self.speedY

def draw(self):
        fill(self.c)
        ellipse(self.x,self.y,self.diameter,self.diameter)

def left(self):
        return self.x - self.diameter / 2
    def right(self):
        return self.x + self.diameter / 2
    def top(self):
        return self.y - self.diameter / 2
    def bottom(self):
        return self.y + self.diameter / 2

class Paddle:
    def __init__(self, x, y, w, h):
        self.x = x
        self.y = y
        self.w = w
        self.h = h
        self.speedY = 0
        self.c = 255

def update(self):
        self.y += self.speedY
        if (self.bottom() > height):
            self.y = height-self.h / 2
        if (self.top() < 0):
            self.y = self.h / 2

def draw(self):
        fill(self.c)
        rect(self.left(), self.top(), self.w, self.h)
		
    def handleIntersect(self, ball):
        verticalCheck = ball.y > self.top() and ball.y < self.bottom()
        horizontalCheck = (ball.left() < self.right() and ball.right() > self.right()) or (ball.right() > self.left() and ball.left() < self.left())
        if verticalCheck and horizontalCheck:
			ball.speedX = -ball.speedX
			ball.speedY = map(ball.y - self.y, -self.h / 2, self.h / 2, -10, 10)

def left(self):
        return self.x - self.w / 2
    def right(self):
        return self.x + self.w / 2
    def top(self):
        return self.y - self.h / 2
    def bottom(self):
        return self.y + self.h / 2

width = 800
height = 600
paddleSpeed = 5

ball = Ball(width / 2, height / 2, 25, 5, 3)
paddles = [Paddle(15, height / 2, 20, 150), Paddle(width - 15, height / 2, 20, 150)]

run()

2024-11-22

How to use