The Red Circle

     I know, that last article was REALLY confusing. Personally, I'd never program a drawing from scratch. It's easier to use images! In this article, we'll be working with pictures.
So, how tedious would it be to put down each individual pixel for a game? That's what pictures are for! First up, I'll show you how to insert an image. First you need to save the following image as Ball.png, and put it in...wherever you keep your Python programs. For me, it's Python 32, and if your computer is anything like mine, your programs folder will be in your Computer section, in Local Disk (C:). Now, here's that picture:

     Remember, Ball.png. Once it's all good and saved, type in this as a new program:


import pygame, sys
pygame.init()
screen=pygame.display.set_mode([640, 480])
screen.fill([255, 255, 255])
ball = pygame.image.load("Ball.png")
screen.blit(ball, [50, 50])
pygame.display.flip()
while True:
    for event in pygame.event.get():
        if event.type == pygame.QUIT: sys.exit()

     When you run the program, it should display a big red dot around the top-left corner.

     Wow. A red dot. That's so amazing. But, hey! We're one step closer to being talented programmers!

     We'll continue all this picture stuff next time. Bye!

Sine Waves

     You all should have seen this coming. I don't know about you, but this is my worst enemy.
     Math.
     Actually, my worst enemy is creative writing, but that set aside, we have math calculations coming into Python. This is math that won't be done for us, such as print(55 * 10000000e+7). This math works with pixels, and Python won't just go around telling you all 307,200 points. It's all in the luck of the mind. But, I will be nice and won't let you do the math. Yet.
     I've set up a program that draws something called a sine wave (it's some sort of wavy line that works with sound, such as spiking when the volume gets louder). It sets up pixels in various spots to create the basic shape of a sine wave. Open your version of Python and enter this into a new program:



import pygame, sys
import math
pygame.init()
screen = pygame.display.set_mode([640, 480])
screen.fill([0, 0, 0])
for x in range(0, 640):
    y = int(math.sin(x/64.0 * 4 * math.pi) * 200 + 240)
    pygame.draw.rect(screen, [255, 255, 255], [x, y, 1, 1], 1)
pygame.display.flip()
while True:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            sys.exit()

     Just look at that line of math! Can anyone follow that?!...eh. We'll discuss the math functions later. When you run the program, you should get this:

     I had to do white against black instead of black against white this time because it looks cool.

     ...Well. This is...a really embarrassing sine wave. It was torn to shreds and all that's left to show is a few white dots. But, hey, this might come in handy later on for a physics game or something.

     Round as those dots may seem, they're completely square. Each dot is 1 pixel squared. Also, here's a note: the width of the pixels are 1. If it was 0, then there would be nothing on the screen.

     Alright, I'm getting sick of that pathetic sine wave I drew. It's time to fix it! Pygame has a method to draw a single line, and a method to draw multiple lines between multiple points. It's known as pygame.draw.lines(), and must meet the 5 requirements to work.

Surface

On what "surface" to draw the line (in our case, screen).

Color

What color the line will be.

Close

The program needs to know whether or not it should connect the last dot to the first one. We don't want to stick a line through our sine wave, so we'll label it False.

Points

A list of points to connect to.

Width

How thick the line is. If the thickness is 0, it will be nothing.

     So, what we'd write is this:

pygame.draw.lines(screen, [255, 255, 255], False, plotPoints, 1)

     But that's only the appearance of the line. Python doesn't know where to place the line, so we'll have to do a things a bit differently. Retype the program to be like this:

import pygame, sys

import math

pygame.init()

screen=pygame.display.set_mode([640, 480])

screen.fill([0, 0, 0])

plotPoints = []

for x in range(0, 640):

    y = int(math.sin(x/640.0 * 4 * math.pi) * 200 + 240)

    plotPoints.append([x, y])

pygame.draw.lines(screen, [255, 255, 255], False, plotPoints, 2)

pygame.display.flip()

while True:

    for event in pygame.event.get():

        if event.type == pygame.QUIT:

            sys.exit()

     Notice that I changed the line's thickness to 2. This is just so it looks better. When you run the program, you should get this:

     I stretched the waves out a little more so they'll look good. Actually, I think there was a typo somewhere. But, there is our complete sine wave! Was that evil or what? This is what happens when you draw with programming.

     I guess that's the end of this article. I challenge you to experiment with the lines and points to see what you can do with them! Good luck, and see you next time!