Tag Archives: how-to

DIY Analog resource monitor for your PC

via Dangerous Prototypes

Sasa Karanovic posted detailed instructions of how to build a physical dashboard for your PC, that is available on GitHub:

The overall architecture is very simple; There is a python script that is running on a PC and collects CPU, memory, network and GPU usage. Then, it sends that information over serial COM port to the hardware monitor board for processing. New voltage values are calculated and passed to the digital-to-analog converter (DAC) which drives analog dials (galvanometers) by applying a voltage that will move the needle to a desired location. Super simple but it get’s the job done.

See the full post at sasakaranovic.com.

Check out the video after the break.

Code a Phoenix-style mothership battle | Wireframe #26

via Raspberry Pi

It was one of gaming’s first boss battles. Mark Vanstone shows you how to recreate the mothership from the 1980 arcade game, Phoenix.

Phoenix’s fifth stage offered a unique challenge in 1980: one of gaming’s first-ever boss battles.

First released in 1980, Phoenix was something of an arcade pioneer. The game was the kind of post-Space Invaders fixed-screen shooter that was ubiquitous at the time: players moved their ship from side to side, shooting at a variety of alien birds of different sizes and attack patterns. The enemies moved swiftly, and the player’s only defence was a temporary shield which could be activated when the birds swooped and strafed the lone defender. But besides all that, Phoenix had a few new ideas of its own: not only did it offer five distinct stages, but it also featured one of the earliest examples of a boss battle – its heavily armoured alien mothership, which required accurate shots to its shields before its weak spot could be exposed.

To recreate Phoenix’s boss, all we need is Pygame Zero. We can get a portrait style window with the WIDTH and HEIGHT variables and throw in some parallax stars (an improvement on the original’s static backdrop) with some blitting in the draw() function. The parallax effect is created by having a static background of stars with a second (repeated) layer of stars moving down the screen.

The mothership itself is made up of several Actor objects which move together down the screen towards the player’s spacecraft, which can be moved right and left using the mouse. There’s the main body of the mothership, in the centre is the alien that we want to shoot, and then we have two sets of moving shields.

Like the original Phoenix, our mothership boss battle has multiple shields that need to be taken out to expose the alien at the core.

In this example, rather than have all the graphics dimensions in multiples of eight (as we always did in the old days), we will make all our shield blocks 20 by 20 pixels, because computers simply don’t need to work in multiples of eight any more. The first set of shields is the purple rotating bar around the middle of the ship. This is made up of 14 Actor blocks which shift one place to the right each time they move. Every other block has a couple of portal windows which makes the rotation obvious, and when a block moves off the right-hand side, it is placed on the far left of the bar.

The second set of shields are in three yellow rows (you may want to add more), the first with 14 blocks, the second with ten blocks, and the last with four. These shield blocks are fixed in place but share a behaviour with the purple bar shields, in that when they are hit by a bullet, they change to a damaged version. There are four levels of damage before they are destroyed and the bullets can pass through. When enough shields have been destroyed for a bullet to reach the alien, the mothership is destroyed (in this version, the alien flashes).

Bullets can be fired by clicking the mouse button. Again, the original game had alien birds flying around the mothership and dive-bombing the player, making it harder to get a good shot in, but this is something you could try adding to the code yourself.

To really bring home that eighties Phoenix arcade experience, you could also add in some atmospheric shooting effects and, to round the whole thing off, have an 8-bit rendition of Beethoven’s Für Elise playing in the background.

Here’s Mark’s code, which gets a simple mothership battle running in Python. To get it working on your system, you’ll first need to install Pygame Zero. And to download the full code, go here.

Get your copy of Wireframe issue 26

You can read more features like this one in Wireframe issue 26, available now at Tesco, WHSmith, all good independent UK newsagents, and the Raspberry Pi Store, Cambridge.

Or you can buy Wireframe directly from Raspberry Pi Press — delivery is available worldwide. And if you’d like a handy digital version of the magazine, you can also download issue 26 for free in PDF format.

Make sure to follow Wireframe on Twitter and Facebook for updates and exclusive offers and giveaways. Subscribe on the Wireframe website to save up to 49% compared to newsstand pricing!

The post Code a Phoenix-style mothership battle | Wireframe #26 appeared first on Raspberry Pi.

How to design and build your own Lithium battery pack

via Dangerous Prototypes

Adam Bender posted detailed instructions of how to design and build a custom DIY lithium battery pack with 18650 cells:

Designing a custom lithium battery pack is a fun way to learn about electricity and engineering. Lithium batteries can be used for countless applications including electric bikes, scooters, vehicles, backup power suppliers, off the grid solutions, and much more.

More details on Adam Bender’s blog. See part one of this series for the battery build.

Check out the video after the break.

Make a keyboard-bashing sprint game | Wireframe issue 23

via Raspberry Pi

Learn how to code a sprinting minigame straight out of Daley Thompson’s Decathlon with Raspberry Pi’s own Rik Cross.

Spurred on by the success of Konami’s Hyper Sports, Daley Thompson’s Decathlon featured a wealth of controller-wrecking minigames.

Daley Thompson’s Decathlon

Released in 1984, Daley Thompson’s Decathlon was a memorable entry in what’s sometimes called the ‘joystick killer’ genre: players competed in sporting events that largely consisted of frantically waggling the controller or battering the keyboard. I’ll show you how to create a sprinting game mechanic in Python and Pygame.

Python sprinting game

There are variables in the Sprinter() class to keep track of the runner’s speed and distance, as well as global constant ACCELERATION and DECELERATION values to determine the player’s changing rate of speed. These numbers are small, as they represent the number of metres per frame that the player accelerates and decelerates.

The player increases the sprinter’s speed by alternately pressing the left and right arrow keys. This input is handled by the sprinter’s isNextKeyPressed() method, which returns True if the correct key (and only the correct key) is being pressed. A lastKeyPressed variable is used to ensure that keys are pressed alternately. The player also decelerates if no key is being pressed, and this rate of deceleration should be sufficiently smaller than the acceleration to allow the player to pick up enough speed.

Press the left and right arrow keys alternately to increase the sprinter’s speed. Objects move across the screen from right to left to give the illusion of sprinter movement.

For the animation, I used a free sprite called ‘The Boy’ from gameart2d.com, and made use of a single idle image and 15 run cycle images. The sprinter starts in the idle state, but switches to the run cycle whenever its speed is greater than 0. This is achieved by using index() to find the name of the current sprinter image in the runFrames list, and setting the current image to the next image in the list (and wrapping back to the first image once the end of the list is reached). We also need the sprinter to move through images in the run cycle at a speed proportional to the sprinter’s speed. This is achieved by keeping track of the number of frames the current image has been displayed for (in a variable called timeOnCurrentFrame).

To give the illusion of movement, I’ve added objects that move past the player: there’s a finish line and three markers to regularly show the distance travelled. These objects are calculated using the sprinter’s x position on the screen along with the distance travelled. However, this means that each object is at most only 100 pixels away from the player and therefore seems to move slowly. This can be fixed by using a SCALE factor, which is the relationship between metres travelled by the sprinter and pixels on the screen. This means that objects are initially drawn way off to the right of the screen but then travel to the left and move past the sprinter more quickly.

Finally, startTime and finishTime variables are used to calculate the race time. Both values are initially set to the current time at the start of the race, with finishTime being updated as long as the distance travelled is less than 100. Using the time module, the race time can simply be calculated by finishTime - startTime.

Here’s Rik’s code, which gets a sprinting game running in Python (no pun intended). To get it working on your system, you’ll first need to install Pygame Zero.

Get your copy of Wireframe issue 23

You can read more features like this one in Wireframe issue 23, available now at Tesco, WHSmith, all good independent UK newsagents, and the Raspberry Pi Store, Cambridge.

Or you can buy Wireframe directly from Raspberry Pi Press — delivery is available worldwide. And if you’d like a handy digital version of the magazine, you can download issue 23 for free in PDF format.

Autonauts is coming to colonise your computers with cuteness. We find out more in Wireframe issue 23.

Make sure to follow Wireframe on Twitter and Facebook for updates and exclusive offers and giveaways. Subscribe on the Wireframe website to save up to 49% compared to newsstand pricing!

The post Make a keyboard-bashing sprint game | Wireframe issue 23 appeared first on Raspberry Pi.

Create a Scramble-style scrolling landscape | Wireframe issue 22

via Raspberry Pi

Weave through a randomly generated landscape in Mark Vanstone’s homage to the classic arcade game Scramble.

Scramble was developed by Konami and released in arcades in 1981. Players avoid terrain and blast enemy craft.

Konami’s Scramble

In the early eighties, arcades and sports halls rang with the sound of a multitude of video games. Because home computers hadn’t yet made it into most households, the only option for the avid video gamer was to go down to their local entertainment establishment and feed the machines with ten pence pieces (which were bigger then). One of these pocket money–hungry machines was Konami’s Scramble — released in 1981, it was one of the earliest side-scrolling shooters with multiple levels.

The Scramble player’s jet aircraft flies across a randomly generated landscape (which sometimes narrows to a cave system), avoiding obstacles and enemy planes, bombing targets on the ground, and trying not to crash. As the game continues, the difficulty increases. The player aircraft can only fly forward, so once a target has been passed, there’s no turning back for a second go.

Code your own scrolling landscape

In this example code, I’ll show you a way to generate a Scramble-style scrolling landscape using Pygame Zero and a couple of additional Pygame functions. On early computers, moving a lot of data around the screen was very slow — until dedicated video hardware like the blitter chip arrived. Scrolling, however, could be achieved either by a quick shuffle of bytes to the left or right in the video memory, or in some cases, by changing the start address of the video memory, which was even quicker.

Avoid the roof and the floor with the arrow keys. Jet graphic courtesy of TheSource4Life at opengameart.org.

For our scrolling, we can use a Pygame surface the same size as the screen. To get the scrolling effect, we just call the scroll() function on the surface to shift everything left by one pixel and then draw a new pixel-wide slice of the terrain. The terrain could just be a single colour, but I’ve included a bit of maths-based RGB tinkering to make it more colourful. We can draw our terrain surface over a background image, as the SRCALPHA flag is set when we create the surface. This is also useful for detecting if the jet has hit the terrain. We can test the pixel from the surface in front of the jet: if it’s not transparent, kaboom!

The jet itself is a Pygame Zero Actor and can be moved up and down with the arrow keys. The left and right arrows increase and decrease the speed. We generate the landscape in the updateLand() and drawLand() functions, where updateLand() first decides whether the landscape is inclining or declining (and the same with the roof), making sure that the roof and floor don’t get too close, and then it scrolls everything left.

Each scroll action moves everything on the terrain surface to the left by one pixel.

The drawLand() function then draws pixels at the right-hand edge of the surface from y coordinates 0 to 600, drawing a thin sliver of roof, open space, and floor. The speed of the jet determines how many times the landscape is updated in each draw cycle, so at faster speeds, many lines of pixels are added to the right-hand side before the display updates.

The use of randint() can be changed to create a more or less jagged landscape, and the gap between roof and floor could also be adjusted for more difficulty. The original game also had enemy aircraft, which you could make with Actors, and fuel tanks on the ground, which could be created on the right-hand side as the terrain comes into view and then moved as the surface scrolls. Scramble sparked a wave of horizontal shooters, from both Konami and rival companies; this short piece of code could give you the basis for making a decent Scramble clone of your own:

Here’s Mark’s code, which gets a Scramble-style scrolling landscape running in Python. To get it working on your system, you’ll first need to install Pygame Zero. And to download the full code, go here.

Get your copy of Wireframe issue 22

You can read more features like this one in Wireframe issue 22, available now at Tesco, WHSmith, and all good independent UK newsagents, and the Raspberry Pi Store, Cambridge.

Or you can buy Wireframe directly from Raspberry Pi Press — delivery is available worldwide. And if you’d like a handy digital version of the magazine, you can also download issue 22 for free in PDF format.

Make sure to follow Wireframe on Twitter and Facebook for updates and exclusive offers and giveaways. Subscribe on the Wireframe website to save up to 49% compared to newsstand pricing!

The post Create a Scramble-style scrolling landscape | Wireframe issue 22 appeared first on Raspberry Pi.

Recreate Super Sprint’s top-down racing | Wireframe issue 21

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Making player and computer-controlled cars race round a track isn’t as hard as it sounds. Mark Vanstone explains all.

The original Super Sprint arcade machine had three steering wheels and three accelerator pedals.

From Gran Trak 10 to Super Sprint

Decades before the advent of more realistic racing games such as Sega Rally or Gran Turismo, Atari produced a string of popular arcade racers, beginning with Gran Trak 10 in 1974 and gradually updated via the Sprint series, which appeared regularly through the seventies and eighties. By 1986, Atari’s Super Sprint allowed three players to compete at once, avoiding obstacles and collecting bonuses as they careened around the tracks.

The original arcade machine was controlled with steering wheels and accelerator pedals, and computer-controlled cars added to the racing challenge. Tracks were of varying complexity, with some featuring flyover sections and shortcuts, while oil slicks and tornadoes posed obstacles to avoid. If a competitor crashed really badly, a new car would be airlifted in by helicopter.

Code your own Super Sprint

So how can we make our own Super Sprint-style racing game with Pygame Zero? To keep this example code short and simple, I’ve created a simple track with a few bends. In the original game, the movement of the computer-controlled cars would have followed a set of coordinates round the track, but as computers have much more memory now, I have used a bitmap guide for the cars to follow. This method produces a much less predictable movement for the cars as they turn right and left based on the shade of the track on the guide.

Four Formula One cars race around the track. Collisions between other cars and the sides of the track are detected.

With Pygame Zero, we can write quite a short piece of code to deal with both the player car and the automated ones, but to read pixels from a position on a bitmap, we need to borrow a couple of objects directly from Pygame: we import the Pygame image and Color objects and then load our guide bitmaps. One is for the player to restrict movement to the track, and the other is for guiding the computer-controlled cars around the track.

Three bitmaps are used for the track. One’s visible, and the other two are guides for the cars.

The cars are Pygame Zero Actors, and are drawn after the main track image in the draw() function. Then all the good stuff happens in the update() function. The player’s car is controlled with the up and down arrows for speed, and the left and right arrows to change the direction of movement. We then check to see if any cars have collided with each other. If a crash has happened, we change the direction of the car and make it reverse a bit. We then test the colour of the pixel where the car is trying to move to. If the colour is black or red (the boundaries), the car turns away from the boundary.

The car steering is based on the shade of a pixel’s colour read from the guide bitmap. If it’s light, the car will turn right, if it’s dark, the car will turn left, and if it’s mid-grey, the car continues straight ahead. We could make the cars stick more closely to the centre by making them react quickly, or make them more random by adjusting the steering angle more slowly. A happy medium would be to get the cars mostly sticking to the track but being random enough to make them tricky to overtake.

Our code will need a lot of extra elements to mimic Atari’s original game, but this short snippet shows how easily you can get a top-down racing game working in Pygame Zero:

Here’s Mark’s code, which gets a Super Sprint-style racer running in Python. To get it working on your system, you’ll first need to install Pygame Zero. And to download the full code, go here.

Get your copy of Wireframe issue 21

You can read more features like this one in Wireframe issue 21, available now at Tesco, WHSmith, and all good independent UK newsagents.

Or you can buy Wireframe directly from Raspberry Pi Press — delivery is available worldwide. And if you’d like a handy digital version of the magazine, you can also download issue 21 for free in PDF format.

Make sure to follow Wireframe on Twitter and Facebook for updates and exclusive offers and giveaways. Subscribe on the Wireframe website to save up to 49% compared to news stand pricing!

The post Recreate Super Sprint’s top-down racing | Wireframe issue 21 appeared first on Raspberry Pi.