[Insert image of a Windows programmer browsing sourceforge] ..damn cant find one

The problem with the whole open-source software idea is when someone actually does make use of the code, and not abide by the licence it is under, a course of legal action against the guilty party is not entirely clear.

Firstly to argue your case you need to be able to compare closed-source proprietary code with yours, and in court demonstrating that your revenue is derived from exclusive access to the source is a good case to dismiss calls for the code to be reviewed.

I think we need to write a program that scans, analyses and tries to find similarities between two pieces of code, that restricts the user actually being able to see the code! What objections could they pull out of there poopholes then?

Secondly if they are found to have used open-source code in their commercial product, violating the terms of the licence, and the accuser decides to sue, where do the proceeds go? To the guy who wrote the code? But his code was based and modified from someone else’s project. Do we proportion it out based on the amount of code written? Time spent? Usefulness of snippet?!

No! We should start a trust fund to which all proceeds go, and the cash will be spent on future development and support of open-source software! Funding of projects should then be apportioned based on user feedback on ideas for improvement to the cause, such as new features to this or that application, or even ‘just make it look better!’ So often something needs to be done for the users sake, but because the programmers can through some hack get it working, no one makes it easy for the average Joe! Seriously if Linux was a car you would need two permanent mechanics!

So what do you think?

Go System >> Preferences >> Sound and change the Device under the Default Mixer Tracks to Playback: Your Soundcard and in the below list select Master.

This one took me awhile..

Anyway I was asked how to pause a script so that you could see the stdout and it brought back memories of the beginning.. So I solved his problem and the funny thing was 5 other people in the chat room thanked me?

So here is how to make your script wait for user input or a predefined time in seconds;

bash 

read -p "Press ENTER to continue.."

sleep 5

raw_input("Press ENTER to continue..")

import time
time.sleep(5)

Dont forget to append the appropriate code to the end of your script.. otherwise it will wait but before anything has been printed to the terminal.

It came to pass one day that I had nothing to do and the applet was teasing me.. with its unused wireless meter (even though I only use wired..) poking at my firm statement that jaunty has to be so far the best OS ever.. I got down, used my windows admin skills inherited from my father combined with my linux guru magic, and fixed the bug in my otherwise perfect install.

Before we start let us put on some protection and backup all that we are about to edit.

mkdir ~/condom; sudo cp /etc/network/interfaces ~/condom/

Firstly edit your interfaces file..

sudo vim /etc/network/interfaces

..or if you dont know how to use vim use your favourite editor, or if you dont know how call up a editor from the terminal at all..

gksudo gedit /etc/network/interfaces

• remove all interfaces except loopback or comment them out

So your interfaces file should look something like this..

# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).

# The loopback network interface
auto lo
iface lo inet loopback

• remove all connections made in your network-manager app

(here is where my windows experience really kicks in..)

• restart

That should be it. If you have DHCP it will automatically connect. If you want you can change it, to a static address, you can.. via the applet! Heh, technology these days advancing so fast for a old timer like me.. born in the days when Metallica release the most successful album ever called “Metallica” and Freddie Mercury one day after announcing he had AIDS died of AIDS..

Program: Hey PC! It seems the user wants to show off the coolness that is a compiz enable linux!
Computer: Cool..
Program: I need some power to do something cool like 1 minutes ago.
Computer: OK. Here you go.
Program: Shit.. I am rendering as if I where running on a pentium 3!
Computer: Really? Well.. err.. I guess we can put foot to pedal, remove restrictions, and go the way my manufacturer intended?
Program: Its OK.. I am done giving my terrible demonstration.
Computer: Well just incase the user wants to show his friend what compiz can do given a second chance I will stay powered up for the next 1 second..
Program: …

Yes.. I’m looking at you ubuntu! To disable the leash choking your system run this command;

sudo update-rc.d -f ondemand remove

Then add the CPU Frequency Monitor applet to your gnome-panel, left click it and set it to Performance. If you have multiple CPU’s right click, go to Preferences and change to the next processor. Left click and switch again.

This stopped the lag I got whenever I rotated the cube in compiz, and removed the jerkiness I got when using cooliris in firefox.

I also noticed improvements when using flash, but only on my 64bit jaunty. I think this is due to to workarounds that ubuntu has to have to run adobe flash, which is a 32bit package?

You will need pygame installed… There are installation instructions on their site. While you are there skim over their tutorials to get you greased up for what you are about to receive.

To get a quick intro to pygame I am going to make a very simple game. All it will consist of is a ball, that bounces… add some sort of user input, maybe some box shaped monsters with a fetish for killing round things and we have ourselves something!

I need somewhere to start off, so I will show you what I slapped up then explain from there. Please look through the source, or don’t and be confused for the rest of the tutorial.

start…

Least, but not last, we must import pygame and other useful stuff into our game;

import pygame
import pygame.locals as pg
from pygame import Rect

This imports the pygame library, then all the useful functions and constants that are regularly used into the pg name-space (you can import into the global name-space but I don’t want to override anything by mistake). I also recommend importing the Rect class into your local name-space as you deal with rectangles alot.

x, y = size = 400, 400

white = (0, 0, 0)
black = (255, 255, 255)
grey = (200, 200, 200)
green = (0, 255, 0)

This is just assigning the screen resolutions and the colour values we will be using later to variables for readability.

pygame.init()
screen = pygame.display.set_mode(size)
screen.fill(grey)
pygame.display.update()

Here we are, the pygame nitty gritty. By calling the init method on pygame you tell it gear up for some action. The next line sets up the canvas you will be painting on by calling the set_mode() method located in the pygame.display class and assigning the surface returned to a variable. We then fill that surface with grey (the colour variable we defined earlier) and update what is displayed so we can see our changes.

I advise you to call pythons builtin help() function on all the methods and classes I have and will mention to see what additional parameters they take and how they are used. For example set_mode() takes the additional flags parameter with several different options, like FULLSCREEN.

ball = Rect(x/2, y/2, 20, 20)
vel = [0.0, 0.0]
elasticity = 0.6
power = 0.6
gravity = 0.5

We want a ball but we are making a rectangle.. wtf? Well I didn’t have to do this. In pygame.draw there are two (actually 3 if you check) ways to make something that looks round: circle and ellipse.
The thing is I wanted the useful bottom, top, left and right attributes the Rect object provides so that I could more easily manipulate the balls position.
The other variables are all used for the physics of our ball and you will see their relevance later.

running = True
go_u = go_d = go_r = go_l = False
clock = pygame.time.Clock()

Just setting up some stuff we need for the main loop, but notice that clock instance hiding amongst initializations. I am utilizing the time capabilities pygame provides by creating an instance of Clock() so I can limit the games fps by calling tick;

while running:
    clock.tick(25)
    ...

I was not sure if I should use pygame.event.get() or use pygame.key.get_pressed() for the following section, but I made a adult like decision and flipped a coin.

    ...

    for event in pygame.event.get():
        if event.type == pygame.QUIT: running = False
        elif event.type == pg.KEYDOWN:
            if event.key == pg.K_ESCAPE: running = False
            elif event.key == pg.K_UP: go_u = True
            elif event.key == pg.K_DOWN: go_d = True
            elif event.key == pg.K_RIGHT: go_r = True
            elif event.key == pg.K_LEFT: go_l = True
        elif event.type == pg.KEYUP:
            if event.key == pg.K_UP: go_u = False
            elif event.key == pg.K_DOWN: go_d = False
            elif event.key == pg.K_RIGHT: go_r = False
            elif event.key == pg.K_LEFT: go_l = False
    ...

This huge chunk of code is pretty simple: if you hit the escape key or press that x button on the top-right corner of the window, then shutdown the loop; if you use the arrow keys then set going_direction (go_{u,d,r,l}) to True; and if you release the arrow key set going_direction to False.

As you can see this code was much shorten by importing those locals into pg. You should probably open up an interactive python session and check what exactly is in pygame.locals, cause I didn’t have a clue.

    ...
    screen.fill(grey, ball)
    old_pos = ball.move(0, 0)
    ...

Again, simple. Fill an area defined by the Rect object, ball, with a colour. We want the colour to be the same as the background surface. We could have just filled the whole screen with grey (by leaving out ball parameter when calling fill) but I am sure you can understand that would take longer, and we can not afford to waste time in the game loop.
Next we make a shallow copy of our ball (I cant find any other way to do this, not sure if this is the best way) for later use when we want to update a portion of our screen.

    ...
    vel[1] += gravity
    if go_u: vel[1] -= power
    if go_d: vel[1] += power
    if go_r: vel[0] += power
    if go_l: vel[0] -= power
    ...

Lets adjust our speed according to what keys are pressed and the gravity your keyboard imposes on our ball. Notice that I didn’t use elif here. If I had then it would find the first true statement, change the speed in the appropriate axis, then skip the rest.
I could get all physicy and apply the mechanics I learnt in A`level math, but lets just use the fact that gravity is a constant acceleration. Therefore all we need to do is increase the balls velocity downwards by an appropriate value each cycle, which you will have to work out yourself by messing around with both the gravity value and your fps to suit your computer.
We used our power variable we made earlier to also give the effect of a pull in the direction defined by our player.

    ...
    ball.move_ip(vel)
    ...

Here is again an example of the cool functions the Rect object has. This is used to move the the ball on our screen in accordance to its velocity. I used move_ip() here instead of move() because I actually want to move the ball, not make a new one and move that.

    ...
    if ball.bottom > y:
        ball.bottom = y
        vel[1] = -abs(vel[1]) * elasticity
    if ball.top < 0:
        ball.top = 0
        vel[1] = abs(vel[1]) * elasticity
    if ball.right > x:
        ball.right = x
        vel[0] = -abs(vel[0]) * elasticity
    if ball.left < 0:
        ball.left = 0
        vel[0] = abs(vel[0]) * elasticity
    ...

Before we write this ball to the screen we make sure it is not off it! This is what this block of code does. It also reverses the direction of movement and applies our elasticity value. This makes it look more realistic, because if you release a ball a distance from the floor in real life and let it bounce it doesn’t come all the way back up.

I also called the abs() function, instead of just reversing the direction, because I wanted to make sure it could never leave our screen say if the ball was moving to fast for the next loop to adjust it correctly.

As I was saying earlier I used the ball.[up,down,left,right] to adjust the ball and put it back on the surface to avoid the ball looking as if it were burying itself into the edge of the screen.

    ...
    pygame.draw.ellipse(screen, green, ball)
    pygame.display.update(ball.union(old_pos))

Last thing we need to do in our loop is draw the ball by calling ellipse() in pygame.draw and update all the changes we have worked to make. ellipse() takes the surface it will write on as the first parameter, then the colour to make the ball, then the Rect object that tells it where to put it and the dimensions.

The final line, following the theme of minimal screen update, calls update() with a rectangle that covers both the current ball position, and the position of the old ball that we erased. We created this Rect object by calling the balls union() method on the copy of the old ball.

stop.

Wow.. anthony.write_tutorial(flags=VERBOSE)

Anyway, there you have it. I will leave it at that for now. No box monsters.. ah. Anyway if you liked the tutorial be sure to leave a comment, digg it, stumble it, whateva… just give me some feed back.

This is a pretty straight forward code so mess around with it to get you key with what it is doing. Change some variables like the colour and ball size, or mess with the elasticity, power and gravity values and check what effects it has. Also take a look at the order of execution in the main loop. The order is very important for the game to run correctly.

One more thing, I highly recommend reading through the pygame cookbook. This is a great resource once you have got a feeling of how pygame works and want to write a game of your own!

Included in this verbal diarrhoea will be python, bash, C, linux and other related tutorials that I have written myself. I find that I cant learn unless I teach and I cant remember unless I record, motivation revealed.

There will be other drivel that you could filter through that I post as a matter of interest or to express various opinions and thoughts on what I see fit.

note: I am dyslexic, so if you see any misspelled words or incorrect English I have an excuse already lined up. Preparation makes perfect.

He consequently lost all his memory and therefore all recall of his caring owner and the games we played.
I swore revenge for the damage that had been done…

1. Move to linux – complete
2. Learn python, bash, C and what ever else is needed for the next step – in progress
3. Write the singularity and name him ‘Dent’ – queued

note2self: don’t forget, again, to get flowers… for Dent.. *cry*