Creators – Week 15

This week we established a palette for our UI design, brought in a custom font, a custom UI background sprite and build a prefab to use when we find a gem that contained an animation.


Before we talk palettes, it’s good idea to introduce a new counting system called hexadecimal. The counting system we usually use is called decimal and it has ten digits, from 0 to 9. Hexadecimal is similar, but it has 16 digits. Counting in hexadecimal looks like this:

0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 1A, 1B, 1C, ....

So 10 (say one-zero, not ten!) written in hexadecimal is 16 in decimal.

The main reason we use hexadecimal when working with computers is that it aligns neatly with the way information is stored inside the computer itself. A byte or 8-bit value can always be written with two hexadecimal digits, a 16-bit value with four hexadecimal digits and so on.


There are combinations of colours that are inherently more pleasing to our eyes and there are rules that allow them to be calculated. There are lots of websites that will calculate a colour palette for you. We chose

You can see that the colour are represented by six hexadecimal digits. This is three bytes (0-255 in decimal, 0-FF in hexadecimal) representing the red, green and blue components of the colour. It’s a tidy way to represent it and easy to share and reuse.

This is the palette I chose for our game:

It’s intended to be bright and cheerful and include some colours with a high contrast with each other.

In Unity we can add these colours to a custom palette, so we can recall them quickly any time we want. At the bottom of any colour-picker dialog you can find the option to create a “Swatch Library”

We can then add the current colour to the library by selecting the last button under “Swatches”.

Custom Font

We wanted a nice font for our game. The right choice really helps set a mode. I choose a font called Brady Bunch Remastered that’s free for non-commercial use. I found it here

In Unity we saved this file to a new folder called Fonts. We then needed to set it up so that Text Mesh Pro could use it. Under the Window | TextMeshPro we used the Font Asset Creator to build a “font atlas” from the BradBunR.ttf font file.

Custom UI Background

The standard UI background in Unity is very plain and boring. I created an image to give our UI elements more character.

We imported this into Unity to our Sprites folder. We then needed to set a few things to allow Unity to use it in a UI. In the Inspector we changed the “Texture Type” to “Sprite (2D and UI)” and “Mesh Type” to “Full Rect”. We then hit the “Apply” button near the bottom of the Inspector to apply these changes.

Unity allows you to set borders on our sprites so that when they’re scaled, the corners don’t change, but the pieces in between stretch instead. This preserves the appearance when the sprite is used as the background to differently sized elements. To specify this we need to first add the 2D Sprite package to Unity and then use the “Sprite Editor” button in the Inspector to open it. We specified 36 for all borders. The hand-drawn blue arrows show how the different regions will stretch when used:

Prefab for when we Find a Gem

We developed a prefab to use when we find a gem. It’s intended to be spawned inside a child of the main camera that places it just in front of the player.

The prefab contains a Canvas. Canvases usually overlay the game screen, but they can be worldspace canvases, that actually exist as objects inside the scene. As Canvases are always huge, we needed to specify a very small scale to bring it down to something that makes sense.

We create a script GemFoundMessage.cs and attach it to the root of our prefab. It’s used to take information about gem was found and use that to update text on the Canvas and to spawn in a copy of the gem (which we can animate).

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using TMPro;

public class GemFoundMessage : MonoBehaviour
    public TMP_Text Text;
    public Transform GemHolder;

    public void SetGemDefinition(GemDefinition gd)
        string message = string.Format("You found a {0} spirit gem!",
        Text.text = message;



To animate in Unity, we first open the Animation window from the Window | Animation menu. It works well if docked at the bottom of the screen where the Console usually is.

We then select the object that we want to animate, and press the Create button in the Animation window.

This makes an Animation Clip and Animator Controller in our project and attaches an Animator component to our GameObject.

With our object selected, we press the “Add Property” (1) button to select the properties we want to animate, we then click in the timeline (2) to select the time at which we want to specify the property value and finally we edit the property value at that time (3).

Code Download

The code for this week’s project is on our GitHub, as always. 

Modellers – Week 15

This week we continued with our tank model.

We created a set of wheels from a cylinder which we then scaled, duplicated and used inset and extrude to provide a little detail on each wheel.

We then created a bezier curve to define the shape of the track across then wheels. Bezier curves are an easy way to defined a smooth shape. They have a number of points through which the curve passes. Each point has a pair of handles. The rotation of these handles defines the angle at which the curve passes through the point. The distance between the handles defines how tightly the curve bends as it approaches the point.

Here are the video instructions for this week:

The updated tank model can be found here.

Creators: Robot Arm


This week we looked at a representation of a robot arm. The body of our robot is allowed to slide horizontally and the arm can pivot at the shoulder (where the upper arm attaches to the body) and at the elbow (where the lower arm attaches to the upper arm).


An important point about this project was to show how transformations add up together. Transformations include translations (moving in straight line), rotations (turning about a pivot point) and scaling (changing size). We’ve used translations and rotations for our robot.

In P5, the origin, or place where the x and y coordinates are both zero is at the upper left-hand corner of the screen. The x coordinate gets bigger as we move right and the y coordinate gets bigger as we move down.

When we translate, we move the origin to somewhere else. This is handy for a few reasons but if we are performing rotations. All rotations happen around the origin, wherever that happens to be at the time.

This diagram shows all the transformations we use for our robot:

Robot DOFs (1)

  1. Translate to move the origin to the centre of the robot body
  2. Translate to move the origin to the shoulder
  3. Upper arm rotation at the shoulder
  4. Translate to move the origin to the elbow
  5. Lower arm rotation at the elbow

Because these transformations stack up on top of each other, this is what each part experiences:

  1. Body – Transformations: 1
  2. Upper Arm – Transformations: 1, 2, 3
  3. Lower Arm – Transformations: 1, 2, 3, 4, 5

The body is only affected by one, but the lower arm is affected by all five.


To move the robot, we set up three variables:

  1. bodyPos to store the body position (our first transformation)
  2. upperArmAngle to store the rotation at the shoulder (our third transformation)
  3. lowerArmAngle to store the rotation at the elbow (our fifth transformation)

We created a function called handleInput() called from the draw() function (which is called every frame). In that we used the keyIsDown() function from P5 to check for keys being held down. We made the left/right arrow keys move the body horizontally, the up/down arrow keys rotate at the shoulder and the Z/X keys to rotate at the elbow.

Source Code

As always, the code can be downloaded from our GitHub repository.

Scratch Advanced – Week 15 – Radio Waves

What are we going to learn this week:

  • A tiny little bit about Waves and how clever they are.
  • A pratical demonstration.
  • Thinking – Yes, it’s tough, you will have to do that part 🙂
  • Coding – Sine Waves

I will hopefully demonstrate how differnt types of waves behave.

I will admit, that I am not an expert here and will probably be unable to answer any of your questions, but you see that’s where you come in and start thinking about these things yourself.

A Pratical Demonstration.

What’s in the Box?

I will bring the Box and we can take a look inside, I might even have two boxes, you never know.




Remember the Gravity simulation we did, well we can do the same with Waves.

We will build a few Transmitters and a Receiver which can be “tuned” in to the different transmissions. In fact this would be an ideal Application to do using the Networking in Scratch. Does anyone remember that from last year?

Lets see how we get on, we might set this up with one person as the Transmitter and one person as the Receiver.

I have some of the coding done to Transmit a Wave, but will need help in building a transmitter and obviously something to broadcast as well 🙂

Ok, I know Iam supposed to put up the code before the day, but better late than never.

Here is the code for the Transmitter of the radio Waves. Careful with the SIN code has there are a few nested calculations there.

















And here is the code for the Reciever.


Intermediate Scratch – Challenge 14 – Build a Network Pong Game!

CDA-S2-Challenge14-NetworkPongThis week’s challenge is to build a 2-player networked Pong game.

This challenge made use of the networking ideas that we covered when writing a network Chat program and previously when we learned about networking.

The big ideas behind this challenge were:

  1. Design of a networked program
  2. Division of labour: there are two programs running on two computers, and we have to decide which is which
  3. Using variables  for exchange of data

Here are the presentation slides from the day, in PDF format: CDA-S2-Challenge14-NetworkPong.pdf

If you would like me to send you these slides in PowerPoint format, feel free to get in touch on Twitter or via the comments!