Advanced Scratch – Week 2 – Buttons and Crazy Images.

What are we going to learn this week…

• How to imitate a Button
• How to use the Pen controls
• How to use sliders

Buttons.

 Wouldn’t it be great if you could have buttons in Scratch, that you can click and make things happen?

Well you can, there might not be a code block to do it, but we can make one.

 You will need a Sprite with Two Costumes

• One for the Up position
• One for the Down Position

 

See how I have given the Sprite a meaningful name and also each costume has a name. The only difference between the sprites is the bottom one has no shadow and is slightly lower and left (covering the shadow).

Cool Tip: You can export the Button Sprite which will save it with all the code as well. This means it is easy to add Buttons to any other Scratch Projects. 

Crazy Images.

We are going to use the Pen Tool to draw some fancy Spirograph like images.

First we need a Sprite that will do the drawing, I just created an invisible Sprite, so you only see the Line being drawn.

Spirographs work using circles, but we are going to use triangles, squares, pentagons, hexagons and heptagons (7 sided).

If you walk 10 steps turn 90 degrees and walk another 10 steps and again and again, you have wlaked in a square, but if you change either how many steps or the angle you turn by a very SMALL amount and just keep[ going you can generate some very interesting patterns.

Sliders.

We will also be using sliders to control the nember of sides to the shape and the change in angles.

Sliders are variables that are displayed on the screen with a slider control to change the value as the program is running. To get the variable to show as a Slider just dbl click on it, once, changes it to a Slider, dbl clicking again, removes the name.

If you right click on the SLider you can set Min and Max values.

The code to create the Spirals is split into two parts. One runs when youclick the Green Flag, this just sets everything up ready.

 

The next piece of code is what does all the work, notice where the Slider variables are used and how the code makes more sense when you give variables descriptive names.