Notes:
This script will make our robot move on our command, but only in one direction.
Have a look at the screenshot above. We have used the “when [space] key pressed” event from Control to run the program. The robot sprite is moved to the centre of the screen using a “go to x: [0] y: [0]” block from Motion (see “Positioning your sprite”, in Lesson 1.3). The rest of the code is placed inside a “repeat until” loop (from Control). Inside the repeat loop, we have an “if” (a conditional statement) that checks if the “up arrow” key has been pressed. This has been set to a “key [up arrow] pressed” event (from Sensing). The “touching [ ]?” block from Sensing is set to “edge”. That means that if the robot touches the edge of the Scratch screen, the event will stop the script. An “event” is something that happens in a program.
In this script, there are two possible situations:
1. The “up arrow” key has been pressed – in which case, the robot will walk up the screen for 20 steps, switching costumes as it does so. 2. The “up arrow” key has not been pressed – in which case, the robot will do nothing.
That’s not going to be very useful. Let’s see if we can do better.
To see an example of this script, open RPiScratch/Projects/robot_v1.
A beginner’s guide to Scratch
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