Finishing our Game Projects

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110401-N-HC601-027

Image from US Navy via Wikipedia Commons

With two more regular dojo sessions to go before our final party and belt awarding ceremony, the finish line’s in sight and we’ve been concentrating on helping people work on their projects.

Some projects are already looking good, and that’s fantastic. Others however aren’t showing a lot of progress.

If you are struggling, please remember – overly ambitious scopes are the things that ruin most game projects. Ask yourself: what are the basic things that will be the most fun in my game? Maybe it’s exploration. Maybe it’s shooting. Whatever it is, get that working as soon as possible. Don’t do ten weapons, do one. Other features can be layered on over time as long as the fundamentals are there. Try hard to have something working for the next session. We’re here to help.

In the next session we’ll talk about the specific belts we’re going to be awarding. We’ll explain how they’re earned and we’ll try to get an idea of how many people are going for each category.

Basic Sample Projects

I briefly showed a number of sample projects that I’d been playing around with this week. These projects are intended to demonstrate certain useful things that you might want to put in your own game.

The first sample project was a modified version of SprocketLeague. The modifications were relatively modest: each car was given its own camera which was set to render into half the screen. The original top-down camera was set to render into a small area at the top of the screen.

The project files are available here.

The second project, called BasicAI, was just an experiment with baking a NavMesh and having an AI character follow you about. For extra fun, the followers spawn every 1.5s and they’re labeled “HipsterISIS” thanks to a very funny gag one of our ninjas made when watching the game run.

The project files for this are here.

Doors Project

This project wasn’t working fully during our session. It is now. The project contains two scenes. Both implement a door but in different ways. The two scenes can be found in the _scenes folder.

The first implementation is a physics based door. There is a box called DoorFrameRight which has a RigidBody component but is constrained so that it can neither move nor rotate:

Screen Shot 2016-05-08 at 14.57.38

Immediately to the left of this is the Door itself. This is also a box with a RigidBody component. In addition, it has a HingeJoint component. This HingeJoint component links it to the DoorFrameRight box. The HingeHoint is just visible as a small orange arrow on  the left hand side of this picture:

Screen Shot 2016-05-08 at 14.56.18.png

The HingeJoint component is positioned exactly where the door and door frame meet and its axis is set to be vertical, as the door is to swing around the vertical. It also has a spring which will close the door again (more or less) once the thing pushing it open moves away:

Screen Shot 2016-05-08 at 14.56.33.png

A regular FPSController can’t push this door, as it has a kinematic RigidBody (no physics), so note that we use the RigidBodyFPSController instead to represent the player in this scene.

The other door works in a very different manner. The door consists of a frame and a “hinge”. The hinge is just an empty GameObject which contains all the parts of the door that will be moving. It’s origin is at the left-hand edge of the door panel; this means that when we change the hinge’s Y rotation, the door will pivot about it’s left-hand side. The hinge’s origin is shown here:

Screen Shot 2016-05-08 at 15.40.36.png

I could have made the hinge rotate in code, but instead I decided to create animations to do the same thing (change the hinge’s Y rotation). To explain how animation works in Unity is beyond the scope of this post, but I’ll give a very broad introduction to it in the next session.

The door has a box collider around it. When it detects that the player has entered the collider, it triggers one of the opening animations (the direction depending on which side of the door it determines the player to be). Once the player leaves the collider, it closes the door again.

Screen Shot 2016-05-08 at 15.59.07

The files for this project are here.

Random Maze Project

This project was started live in our last session on the suggestion of one of the ninjas; it generates a random maze using a very simple algorithm.

An empty GameObject called MazeGenerator is placed in the scene. In its Start method, it constructs a random maze which appears in the scene. An FPSController from Standard Assets allows us to navigate this maze and try to find our way out.

The MazeGenerator constructs a 2D array of bool values to represent the maze. All the values in this array are ‘false’ by default and we take this to mean ‘solid’. Taking a point in the centre of the array we mark it ‘true’ to indicate an empty space. We then randomly pick a direction from North, South, East or West and set a new position. We check if we’ve moved outside the bounds of the array yet, if not, we mark this as another empty space and continue until we are outside.

Once we have this maze generated, we know we have a path from the centre (the start) to the exit (the outside of the maze). We loop over all elements in our array and place a solid block (from a prefab) everywhere we find a ‘false’, unless we’re at the edge of the maze in which case we place a special prefab that detect the player and plays a sound. This is our ‘exit’. For a ‘true’ we do nothing. The picture below shows one such generated maze from above.

Screen Shot 2016-05-08 at 18.35.04.png

To make this more fun to play, we also added a script to the FPSController to drop “breadcrumbs” as we move. This shows where we’ve already been so that going around in circles shouldn’t be a problem.

The files for this project are available here.

PiDojo- Projects and Belts

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Sorry for not posting for a while, we haven’t covered much new material in the last few weeks.

Today we finally nailed down what our projects are going look like and I think we have some very impressive ideas to work on for the next couple of weeks. By the last session we will be displaying devices like a flood gauge, a food and recipe management system, a retro arcade console, a scalextric racing game timer, a survey/voting machine and a device to help the visually impaired recognise the contents of food cans.

Projects are important for two reasons, they encourage Ninjas to work on their own and they will be the basis for awarding belts.

This year for belts in the Raspberry Pi and Electronics group Ninjas will be examined on more than just code, they will also have to speak about the reason they chose to do the project they did, they will have to explain the various hardware components they used and they will have to create a poster for their project.

I’m looking forward to a busy few weeks in the PiDojo group.

 

Review and a Couple of Sample Projects

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This week we did a review of everything we’ve covered so far in Unity this year. It was a really usefully exercise as we ramp up to doing our own projects. People talked about their project ideas and I even got so see a few things running. I was impressed with the ingenuity and inventiveness. As I explained, over the coming few weeks, I won’t be presenting much in the way of new material. We will instead concentrate on getting our projects running and polishing them to the best of our ability.

I presented a couple of small sample projects intended to inspire game project ideas. The first was a top-down, single-keyboard, two-player game where two cars complete to drive a ball into their opponent’s goal area. If this sounds familiar, then you’ve heard of Rocket League. This low-rent version I dubbed “Sprocket League”. It can be downloaded from here. It uses the car from Standard Assets, slightly modified to allow the input axes to be defined in the inspector so that each can be controller independently. The red car uses the arrow keys and the blue keys uses WSAD for movement. To make it into a full game some means of keeping score and timing the game would be needed.

Screen Shot 2016-04-18 at 22.58.09.png

I also posted a basic sliding tiles game based on 2048. It is intended to show that we can achieve a 2D game appearance, even while using the 3D elements we have been working with. Although the basic game mechanics are there, it would ideally need a lot of work to bring it up to a reasonable standard. The real game provides a lot more visual feedback to the user than this version. Again, it can be downloaded from here. For those that recall, my broken attempt at making the tiles animate can be enabled via the “Show Me The Broken Movement” checkbox on the GameController object.

Screen Shot 2016-04-18 at 22.54.20.png

Best of luck working on your projects over the next two weeks and I’ll see you all when we return!

Scratch Beginners – Challenge 14 – Create a Piano

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This week and part of last week we created a piano! The initial keyboard looked like this:
 cda_s5_challenge_14_piano_keys

Each white and black key is a separate SPRITE. We began by drawing the white Middle C SPRITE which has two costumes. The first costume is white and the 2nd is a different colour (you choose) that flashes up when the SPRITE is CLICKED. This helps us to see which sprite is responding to the click.

Continue reading →

Scratch Advanced: General Purpose Wireframe 3D Engine

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This week in Scratch advanced we took on the ambitious task of writing a general-purpose 3d wireframe engine.  The goal here was to build an engine that we could use to view any structure in 3-dimensions as though we had x-ray vision.   We didn’t really know how it might turn out but were delighted with the results!  If you just want the code, skip to the bottom!

We didn’t quite know how to start this so we Googled 3D and Wireframe, and we found this article on wikipedia that really helped us understand what it was:https://en.wikipedia.org/wiki/Wire-frame_model

wireframe examples

Continue reading →

Shooting Mechanics In Unity

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It was a thrill to have such significant games industry figures come to visit us on Saturday. The mentors, dads and dad-mentors were probably the most excited; Wolfenstein 3D, Doom and Quake were probably the most exhilarating games of our generation.

I was unsatisfied with how much benefit people were getting from continuing with the Tanks tutorial and I decided that we’d looked at it enough. Partially because I know some people want to implement shooting for their own projects and partially because one of our guests had invented the entire first-person-shooter genre, I decided to do a project to demonstrate different ways of implementing shooting in a game.

Please excuse the tinny sound; I was using the computers built in microphone.

There are two main ways to handle shooting: ray-casting and physics-based projectiles. We’re going to do both so lets discuss them in turn.

Ray-casting

Ray-casting uses mathematics to determine if a target is in our cross-hairs and, if it is, registers a hit instantly. It’s a good technique to use where the bullet is very fast moving and distances are relatively short. Regardless of action movie tropes, nobody is dodging a fast-moving bullet in real-life!

In Unity the Physics class contains several Raycast methods (documentation here). They all look along a line from a point and return ‘true’ if that line crosses through a Collider. The specific version we’re using can fill in a RaycastHit object with information about what it hit, if it hit anything.

To determine if we hit anything we must:

  1. Find the position and forward direction of the FPS Camera. This represents where we are and where we’re looking towards.
  2. Call Physics.Raycast with this information. If it didn’t cross any colliders, then we are finished.
  3. If it did hit something, then we check to see if that object is a target. We have tagged all target objects in the scene as “Target” so we can easily check this.
  4. If it is a target, we perform the effect we want. In this case, we push the target away from us with force applied to its RigidBody . In another case, we might want to actually destroy the GameObject instead.

Physics-based projectiles

A physics-based projectile is actually an object in the scene. It has a Collider so that it can detect collisions and a RigidBody so that it is affected by physics.

In many cases of physics-based projectiles, the Collider is simply a trigger and once an collision is detected, an effect, such as reducing the target’s health, is applied to the target.

Our specific physics-based projectile weapon is a cannonball. In this specific case, we actually allow the cannonball to hit the target and the physics engine takes care of the effect (knocking the target away).

The general steps that we need for physics-based projectiles are:

  1. Find the position and forward direction of the FPS Camera. This represents where we are and where we’re looking towards.
  2. Instantiate an instance of our projectile prefab. Position it so that it’s slightly in front of us and not intersecting with the FPS Controller’s own Collider.
  3. Give the projectile some forward velocity.
  4. Either:
    1. Have the projectile detect collisions and perform an appropriate effect on the target, or
    2. Simply allow the physics engine to take care of the impact.

The cannonball prefab has a small script attached to it. It detects collisions. Once the first collision is detected, a coroutine is launched. This coroutine waits for two seconds and then destroys the GameObject. This means that cannonballs have a limited life-span and don’t end up littered all over our level.

Area-effect weapon

We have also implemented an area-effect weapon, namely a grenade. In many ways it is similar to the cannonball but we project it with a more modest velocity.

Once created, however, it’s behaviour is very different. A coroutine is launched as soon as it is created. This coroutine waits for a few seconds to mimic a grenade fuse. It then “explodes”.

To explode, the grenade does the following:

  1. Plays an explosion sound on it’s own AudioSource.
  2. Instansiates a particle-effect prefab at the grenade’s location to display an visual explosion effect.
  3. Disables the grenade’s MeshRender component so that he body of the grenade can’t be seen any more.
  4. Uses Physics.OverlapSphere (documentation here) to find all Colliders within a given radius of the grenade
  5. Loops over these Colliders. If the collider is not attached to an active GameObject or if that GameObject is not tagged as a target, we ignore it.
  6. If it is an active target, we use RigidBody.AddExplosionForce (documentation here) to apply an explosion force, emanating from the grenade’s position, to the target.

Two seconds after the “explosion” the grenade GameObject, now invisible, destroys itself to remove itself from the scene. This short delay gives time for scripts to complete and sounds to finish playing.

Please note that although the grenade wasn’t working correctly on Saturday during our session, it’s fully functional now.

Gun selection

Gun selection is handled using the “[” and “]” keys. In the past we have tended to use Input.GetAxis to detect user input. This is good for where we wish to perform an action continuously as long as a key is held down. It’s not so good where we wish to perform a since action in response to a single keystroke. For that, using Input.GetKeyDown (documentation here) is better and that’s what we do.

The selected weapon is stored using an enum. An enum is a special variable type which can only take one of a number of pre-defined values. Since we have a limited list of weapons, three to be exact, this works well for us.

Putting it all together

Screen Shot 2016-04-12 at 21.17.02

Our level is a simple terrain. It’s been textured and had trees, grass and a wind zone added to it. There is a simple lake. A few target spheres have been positioned around the map and a box containing a number of small targets has been created as a good place to test the grenade in particular.

A standard first person controller prefab has been added to the scene. Our own GunController script has been attached to it as a component. GunController handles all the aiming and firing of the weapons.

Sound effects for the project are all from www.freesound.org with thanks to the original creators. All other third party assets are from the Unity Standard Assets pack.

Downloading the project

The project can be downloaded from DropBox here. Please ensure you have updated to Unity 5.3.4 before opening this project. Be aware, it’s relatively large at 160MB+.

 

Brenda and John Romero, renowned game developers, speaking at CoderDojo Athenry on Saturday 9 April 2016

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romeros

We are very excited to announce that Brenda and John Romero, who between them have been involved in developing exceptional games such as Doom, Quake, Tom Clancy’s Ghost Recon, and Dungeons & Dragons, will be at CoderDojo Athenry on Saturday 9 April 2016. They will be speaking to us about their extensive experience as leading game developers. They will be joined by their 11-year old son Donovan, who has also started developing games.

Brenda and John have recently moved to Galway from the West Coast USA, and are currently in the process of establishing a game studio, called Romero Games, in Galway. Their brief biographies are below.

Regular attendees at CoderDojo Athenry are welcome to bring a friend if they wish. These talks should be really fascinating for our budding coders and game designers in CoderDojo Athenry, and inspirational for boys and girls alike!

PS: Huge credit to Kieran (lead mentor of the Unity stream) for organising this!

 

Brenda Romero 

Brenda is a game designer, artist, academic, and Fulbright Fellow. She has been in the games industry since the early 1980s. Her credits include such notable games series as Tom Clancy’s Ghost Recon, Wizardary and Dungeons & Dragons.  She’s previously sat on board of the International Game Developers Association (IGDA) and chaired several Special Interest Groups (SIGs) including one representing Women in Games. 

John Romero

John is best known as the founder of Id software. An exceptional programmer and game designer, he is the inventor of the “deathmatch”. His best known games include such timeless classics as Commander Keen, Wolfenstein 3D, Doom and Quake each of which broke new ground, both in technical and gameplay terms and even spawned new genres.

Additional 

John and Brenda are currently in the process of establishing a game studio, called Romero Games, in Galway. Their son Donovan, also visiting us, is writing a game with the help of his Dad and friends and will hopefully be demonstrating it on the day.

 

ModderDojo 2016: Adding a Crafting Recipe in Scriptcraft

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craftdiamonds

In a post from last year, we saw how to create crafting recipes in Java modding:

https://cdathenry.wordpress.com/2014/01/19/modderdojo-java-modding-6-creating-our-first-mod-adding-a-crafting-recipe/

It is also possible to do the same thing in Scriptcraft. Here is the code for a dirt to diamonds recipe in Scriptcraft:

Note: write the code in a file called something like “recipe1.js” and put it in the same folder as your other Scriptcraft mod (a sub-folder of scriptcraft – plugins). Note that this is the entire code – it does NOT go inside a function definition.

[code language="javascript"]
// Scriptcraft recipe for dirt to diamonds
var recipes = require('recipes');
var items = require('items'); 

// Here is the recipe: result from ingredients in a shape.
var dirt2diamond = {result: items.diamondBlock(10),
                    ingredients: {D: items.dirt(1)},
                    shape: [ ' D ',
                             'D D',
                             ' D ' ]};

// add the recipe to  the server
recipes.add(dirt2diamond);
[/code]

The code is reasonably easy to understand, I think. The result is a stack of 10 diamondBlock items, there is a single ingredient which is a dirt block that we indicate with a variable ‘D’, and they are arranged in a diamond shape. I have put in extra line breaks to make the shape clearer, but this is not necessary.

You can have more than one ingredient. Here is another example:

[code language="javascript"]
// A second recipe:
// diamond block made with a diagonal line of 2 dirt , 1 cobblestone, and 2 dirt
var recipe2 = {result: items.diamondBlock(1),
               ingredients: {D: items.dirt(2), C: items.cobblestone(1)},
               shape: [ 'D  ', ' C ', '  D' ]};
// add the recipe to  the server
recipes.add(recipe2);
[/code]

PiDojo- Emails, Tweets and Spreadsheets

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Sorry for the delay in posting, I’ve been very busy over the last couple of weeks.

Up until now we’ve mainly looked at what we can do with the GPIO Pins on the Raspberry Pi but over the last two weeks we looked at how we might make information from our scripts available to the world outside.

Two weeks ago (Sat 5th Mar.) we looked at how we might use the internet to share data. Although the  Pi is capable of running a web server and we could build a few web pages fairly quickly there are easier ways of getting information to the public. We can use Twitter to broadcast information and we can use Email for more targeted sharing.

The tutorials in my notes Email and Twitter will show you how to set up the Email and Twitter modules for Python on the Raspberry Pi and you can see our code here.tweet

Last Week (Sat 12th Mar.) we learned how to share data using a Spreadsheet. The tutorial in my notes spreadsheets will show you how to install the XLWT(Excel Write) Library for Python and you can use our code here to create the spreadsheet shown below.

Capture

Unity – Tanks Tutorial Part 3

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Hey folks, we had a quite complicated session this week which discussed a lot of new concepts.

Screen Shot 2016-03-13 at 21.07.33Screen Shot 2016-03-13 at 21.07.10

We talked about the difference between perspective cameras and orthogonal cameras. With perspective cameras, as shown in the first image above, things appear smaller the further they are from the camera. With an orthogonal camera, as shown above in the second image, they appear the same size, regardless of how far they are from the camera.

The screen, and by extension, the camera which draws into that screen has an aspect ratio. This is defined as the width divided by the height. For example, a standard 1080p HD screen of has 1920 x 1024 pixels. This is an aspect ratio of 1.875. Our aspect ratio depends on how we’ve sized our game panel.

The camera in the tanks game is an orthogonal camera and the amount it can see is determined by it’s size. Whatever the camera’s size is, twice that distance in world units will be shown vertically by the camera. Our camera’s size is 5 so that means we can see 10 world distance units vertically and (10 x aspect ratio) distance units horizontally.

The code we showed the last day tries to position the camera at the average position between the tanks and size it so that both tanks fit in at the same time.

One unusual thing  that it does is to ensure smooth movement of the camera by not jumping it instantly to the place we want it to be, or the size we want it to be, but rather using the Vector3.SmoothDamp() method. This method allows us to specify two vectors, one representing the current value and the second representing value we’d like to get to, and returns a vectors that is someway from the first to the second such that it gives a smooth, as opposed to sudden or jerky, movement:

        transform.position = Vector3.SmoothDamp(transform.position, 
                                                m_DesiredPosition, 
                                                ref m_MoveVelocity, m_DampTime);

 

I’ve completed the health bar, as promised, and we won’t be doing that at Dojo. Just download the up-to-date project file from here, and we will start with it next week.

Remember to be working on your own projects! See you next week.