Tag Archives: Python

Code your own Donkey Kong barrels | Wireframe issue 24

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Replicate the physics of barrel rolling – straight out of the classic Donkey Kong. Mark Vanstone shows you how.

Released in 1981, Donkey Kong was one of the most important games in Nintendo’s history.

Nintendo’s Donkey Kong

Donkey Kong first appeared in arcades in 1981, and starred not only the titular angry ape, but also a bouncing, climbing character called Jumpman – who later went on to star in Nintendo’s little-known series of Super Mario games. Donkey Kong featured four screens per level, and the goal in each was to avoid obstacles and guide Mario (sorry, Jumpman) to the top of the screen to rescue the hapless Pauline. Partly because the game was so ferociously difficult from the beginning, Donkey Kong’s first screen is arguably the most recognisable today: Kong lobs an endless stream of barrels, which roll down a network of crooked girders and threaten to knock Jumpman flat.

Barrels in Pygame Zero

Donkey Kong may have been a relentlessly tough game, but we can recreate one of its most recognisable elements with relative ease. We can get a bit of code running with Pygame Zero – and a couple of functions borrowed from Pygame – to make barrels react to the platforms they’re on, roll down in the direction of a slope, and fall off the end onto the next platform. It’s a very simple physics simulation using an invisible bitmap to test where the platforms are and which way they’re sloping. We also have some ladders which the barrels randomly either roll past or sometimes use to descend to the next platform below.

Our Donkey Kong tribute up and running in Pygame Zero. The barrels roll down the platforms and sometimes the ladders.

Once we’ve created a barrel as an Actor, the code does three tests for its platform position on each update: one to the bottom-left of the barrel, one bottom-centre, and one bottom-right. It samples three pixels and calculates how much red is in those pixels. That tells us how much platform is under the barrel in each position. If the platform is tilted right, the number will be higher on the left, and the barrel must move to the right. If tilted left, the number will be higher on the right, and the barrel must move left. If there is no red under the centre point, the barrel is in the air and must fall downward.

There are just three frames of animation for the barrel rolling (you could add more for a smoother look): for rolling right, we increase the frame number stored with the barrel Actor; for rolling to the left, we decrease the frame number; and if the barrel’s going down a ladder, we use the front-facing images for the animation. The movement down a ladder is triggered by another test for the blue component of a pixel below the barrel. The code then chooses randomly whether to send the barrel down the ladder.

The whole routine will keep producing more barrels and moving them down the platforms until they reach the bottom. Again, this is a very simple physics system, but it demonstrates how those rolling barrels can be recreated in just a few lines of code. All we need now is a jumping player character (which could use the same invisible map to navigate up the screen) and a big ape to sit at the top throwing barrels, then you’ll have the makings of your own fully featured Donkey Kong tribute.

Here’s Mark’s code, which sets some Donkey Kong Barrels rolling about 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 24

You can read more features like this one in Wireframe issue 24, 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 24 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 your own Donkey Kong barrels | Wireframe issue 24 appeared first on Raspberry Pi.

Your new free online training courses for the autumn term

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Over the autumn term, we’ll be launching three brand-new, free online courses on the FutureLearn platform. Wherever you are in the world, you can learn with us for free!

Three people looking facing forward

The course presenters are Pi Towers residents Mark, Janina, and Eirini

Design and Prototype Embedded Computer Systems

The first new course is Design and Prototype Embedded Computer Systems, which will start on 28 October. In this course, you will discover the product design life cycle as you design your own embedded system!

A diagram illustrating the iterative design life cycle with four stages: Analyse, design, build, test

You’ll investigate how the purpose of the system affects the design of the system, from choosing its components to the final product, and you’ll find out more about the design of an algorithm. You will also explore how embedded systems are used in the world around us. Book your place today!

Programming 103: Saving and Structuring Data

What else would you expect us to call the sequel to Programming 101 and Programming 102? That’s right — we’ve made Programming 103: Saving and Structuring Data! The course will begin on 4 November, and you can reserve your place now.

Illustration of a robot reading a book called 'human 2 binary phrase book'

Programming 103 explores how to use data across multiple runs of your program. You’ll learn how to save text and binary files, and how structuring data is necessary for programs to “understand” the data that they load. You’ll look at common types of structured files such as CSV and JSON files, as well as how you can connect to a SQL database to use it in your Python programs.

Introduction to Encryption and Cryptography

The third course, Introduction to Encryption and Cryptography, is currently in development, and therefore coming soon. In this course, you’ll learn what encryption is and how it was used in the past, and you’ll use the Caesar and Vigenère ciphers.

The Caesar cipher is a type of substitution cipher

You’ll also look at modern encryption and investigate both symmetric and asymmetric encryption schemes. The course also shows you the future of encryption, and it includes several practical encryption activities, which can be used in the classroom too.

National Centre for Computing Education

If you’re a secondary school teacher in England, note that all of the above courses count towards your Computer Science Accelerator Programme certificate.

Group shot of the first NCCE GCSE accelerator graduates

The very first group of teachers who earned Computer Science Accelerator Programme certificates: they got to celebrate their graduation at Google HQ in London.

What’s been your favourite online course this year? Tell us about it in the comments.

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Estefannie’s Jurassic Park goggles

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When we invited Estefannie Explains It All to present at Coolest Projects International, she decided to make something cool with a Raspberry Pi to bring along. But being Estefannie, she didn’t just make something a little bit cool. She went ahead and made Raspberry Pi Zero-powered Jurassic Park goggles, or, as she calls them, the world’s first globally triggered, mass broadcasting, photon-emitting and -collecting head unit.

Make your own Jurassic Park goggles using a Raspberry Pi // MAKE SOMETHING

Is it heavy? Yes. But these goggles are not expensive. Follow along as I make the classic Jurassic Park Goggles from scratch!! The 3D Models: https://www.thingiverse.com/thing:3732889 My code: https://github.com/estefanniegg/estefannieExplainsItAll/blob/master/makes/JurassicGoggles/jurassic_park.py Thank you Coolest Projects for bringing me over to speak in Ireland!! https://coolestprojects.org/ Thank you Polymaker for sending me the Polysher and the PolySmooth filament!!!!

3D-printing, sanding, and sanding

Estefannie’s starting point was the set of excellent 3D models of the iconic goggles that Jurassicpaul has kindly made available on Thingiverse. There followed several 3D printing attempts and lots of sanding, sanding, sanding, spray painting, and sanding, then some more printing with special Polymaker filament that can be ethanol polished.

Adding the electronics and assembling the goggles

Estefannie soldered rings of addressable LEDs and created custom models for 3D-printable pieces to fit both them and the goggles. She added a Raspberry Pi Zero, some more LEDs and buttons, an adjustable headgear part from a welding mask, and – importantly – four circles of green acetate. After quite a lot of gluing, soldering, and wiring, she ended up with an entirely magnificent set of goggles.

Here, they’re modelled magnificently by Raspberry Pi videographer Brian. I think you’ll agree he cuts quite a dash.

Coding and LED user interface

Estefannie wrote a Python script to interact with Twitter, take photos, and provide information about the goggles’ current status via the LED rings. When Estefannie powers up the Raspberry Pi, it runs a script on startup and connects to her phone’s wireless hotspot. A red LED on the front of the goggles indicates that the script is up and running.

Once it’s running, pressing a button at the back of the head unit makes the Raspberry Pi search Twitter for mentions of @JurassicPi. The LEDs light up green while it searches, just like you remember from the film. If Estefannie’s script finds a mention, the LEDs flash white and the Raspberry Pi camera module takes a photo. Then they light up blue while the script tweets the photo.

All the code is available on Estefannie’s GitHub. I love this project – I love the super clear, simple user experience provided by the LED rings, and there’s something I really appealing about the asynchronous Twitter interaction, where you mention @JurassicPi and then get an image later, the next time googles are next turned on.

Extra bonus Coolest Projects

If you read the beginning of this post and thought, “wait, what’s Coolest Projects?” then be sure to watch to the end of Estefannie’s video to catch her excellentCoolest Projects mini vlog. And then sign up for updates about Coolest Projects events near you, so you can join in next year, or help a team of young people to join in.

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Pulling Raspberry Pi translation data from GitHub

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What happens when you give two linguists jobs at Raspberry Pi? They start thinking they can do digital making, even though they have zero coding skills! Because if you don’t feel inspired to step out of your comfort zone here — surrounded by all the creativity, making, and technology — then there is no hope you’ll be motivated to do it anywhere else.

two smiling women standing in front of a colourful wall

Maja and Nina, our translation team, and coding beginners

Maja and I support the community of Raspberry Pi translation volunteers, and we wanted to build something to celebrate them and the amazing work they do! Our educational content is already available in 26 languages, with more than 400 translations on our projects website. But our volunteer community is always translating more content, and so off we went, on an ambitious (by our standards!) mission to create a Raspberry Pi–powered translation notification system. This is a Raspberry Pi that pulls GitHub data to display a message on a Sense HAT and play a tune whenever we add fresh translated content to the Raspberry Pi projects website!

Breaking it down

There were three parts to the project: two of them were pretty easy (displaying a message on a Sense HAT and playing a tune), and one more challenging (pulling information about new translated content added to our repositories on GitHub). We worked on each part separately and then put all of the code together.

Two computers and two pastries

Mandatory for coding: baked goods and tea

Displaying a message on Sense HAT and playing a sound

We used the Raspberry Pi projects Getting started with the Sense HAT and GPIO music box to help us with this part of our build.

At first we wanted the Sense HAT to display fireworks, but we soon realised how bad we both are at designing animations, so we moved on to displaying a less creative but still satisfying smiley face, followed by a message saying “Hooray! Another translation!” and another smiley face. LED screen displaying the message 'Another translation!'

We used the sense_hat and time modules, and wrote a function that can be easily used in the main body of the program. You can look at the comments in the code above to see what each line does:

Python code snippet for displaying a message on a Sense HAT

So we could add the fun tune, we learned how to use the Pygame library to play sounds. Using Pygame it’s really simple to create a function that plays a sound: once you have the .wav file in your chosen location, you simply import and initialise the pygame module, create a Sound object, and provide it with the path to your .wav file. You can then play your sound:

Python code snippet for playing a sound

We’ve programmed our translation notification system to play the meow sound three times, using the sleep function to create a one-second break between each sound. Because why would you want one meow if you can have three?

Pulling repository information from GitHub

This was the more challenging part for Maja and me, so we asked for help from experienced programmers, including our colleague Ben Nuttall. We explained what we wanted to do: pull information from our GitHub repositories where all the projects available on the Raspberry Pi projects website are kept, and every time a new language directory is found, to execute the sparkles and meow functions to let us and EVERYONE in the office know that we have new translations! Ben did a bit of research and quickly found the PyGithub library, which enables you to manage your GitHub resources using Python scripts.

Python code snippet for pulling data from GitHub

Check out the comments to see what the code does

The script runs in an infinite loop, checking all repositories in the ‘raspberrypilearning’ organisation for new translations (directories with names in form of xx-XX, eg. fr-CA) every 60 minutes. Any new translation is then printed and preserved in memory. We had some initial issues with the usage of the PyGithub library: calling .get_commits() on an empty repository throws an exception, but the library doesn’t provide any functions to check whether a repo is empty or not. Fortunately, wrapping this logic in a try...except statement solved the problem.

And there we have it: success!

Demo of our Translation Notification System build

Subscribe to our YouTube channel: http://rpf.io/ytsub Help us reach a wider audience by translating our video content: http://rpf.io/yttranslate Buy a Raspberry Pi from one of our Approved Resellers: http://rpf.io/ytproducts Find out more about the #RaspberryPi Foundation: Raspberry Pi http://rpf.io/ytrpi Code Club UK http://rpf.io/ytccuk Code Club International http://rpf.io/ytcci CoderDojo http://rpf.io/ytcd Check out our free online training courses: http://rpf.io/ytfl Find your local Raspberry Jam event: http://rpf.io/ytjam Work through our free online projects: http://rpf.io/ytprojects Do you have a question about your Raspberry Pi?

Our ideas for further development

We’re pretty proud that the whole Raspberry Pi office now hears a meowing cat whenever new translated content is added to our projects website, but we’ve got plans for further development of our translation notification system. Our existing translated educational resources have already been viewed by over 1 million users around the world, and we want anyone interested in the translations our volunteers make possible to be able to track new translated projects as the go live!

One way to do that is to modify the code to tweet or send an email with the name of the newly added translation together with a link to the project and information on the language in which it was added. Alternatively, we could adapt the system to only execute the sparkles and meow functions when a translation in a particular language is added. Then our more than 1000 volunteers, or any learner using our translations, could set up their own Raspberry Pi and Sense HAT to receive notifications of content in the language that interests them, rather than in all languages.

We need your help

Both ideas pose a pretty big challenge for the inexperienced new coders of the Raspberry Pi translation team, so we’d really appreciate any tips you have for helping us get started or for improving our existing system! Please share your thoughts in the comments below.

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Make a keyboard-bashing sprint game | Wireframe issue 23

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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

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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.