In this lesson we will program the arrow keys on your keyboard to control a car to drive it around racing tracks that we create using the backdrop editor.
Create a new Scratch project and delete the cat sprite.
Go to the Scratch website using the link below and click on the 'Create' link in the blue bar at the top.
By default, each new project starts with the cat sprite already added. To delete the cat click on the x in the blue circle beside the cat in the sprite list.
Included with this step is a red car picture that we're going to upload into our Scratch project. First download the picture file onto your computer and then upload it into your project.
To download a picture to your computer, right click on the picture and then click on 'Save image as...'
You can upload images and sprite files into your project. To upload a sprite follow these steps:
- First save the image or sprite file onto your computer. You do this by right clicking on the image or link and then selecting 'Save image/link as...'.
- Choose a location on your computer such as your desktop and save the file.
- In your Scratch project, put your mouse over the Choose a Sprite button.
- Click on the 'Upload Sprite' button.
- Go to the folder you saved your file.
- Select the file and click 'Open'.
The new sprite will upload into your project and appear in the stage area.
As the car sprite is very large, we'll need to shrink it so that it has room to move around. We're going to shrink it to 10% of it's original size. Add the following code to the car sprite.
when green flag clicked
set size to (10) %
Click on the green flag and the car will shrink to a smaller size.
We're going to use the backdrop editor to draw a racing track. To open the backdrop editor do the following:
- Click on the stage backdrop in the bottom right. A blue box should appear around it.
- Click on the backdrops tab in the top left. You should now see the backdrop editor.
Next we're going to draw a race track. First we will colour the background green and then we will draw a black track. Follow these steps:
- Click the Convert to Bitmap button.
- Select the colour green in the Fill tool.
- Click on the Paint Bucket tool.
- Click on the backdrop to change it's colour to green.
- Click on the Convert to Vector button.
- Click on the Brush tool.
- Select the colour black in the Fill tool.
- Set the thickness of the brush to be 90.
- Draw a simple loop track by holding down the left button, moving your mouse and then releasing the left button.
Drag your car in the stage area and place it on your track.
We want the car to always start in this position when we click the green flag so add the following code to the car sprite underneath the set size to 10 % block.
when green flag clicked
set size to (10) % // add new blocks under here
go to x:(0) y:(0)// these will be prefilled with the current location of the car
point in direction (90)// point to the right
Note: When you use a go to x: 0 y: 0 block the x and y values will be prefilled with the current position of your car. This is why you should position your car on the track first and then drag in this block.
This lesson is copyright of Coding Ireland. Unauthorised use, copying or distribution is not allowed.
Scratch is developed by the Lifelong Kindergarten Group at the MIT Media Lab. It is available for free at https://scratch.mit.edu