In this add-on, you’ll use cool effects in Scratch to make it look like the stadiumis celebrating with the athletes. First, click on the stage to make sure you’reprogramming it, not the sprite. From the “looks” menu, drag the “changeeffect by” block into the scripts area. Click the dropdown to see lots of differentchoices to explore. Right now, it reads “change color effect by.” Click on the block. Thebackground changes colors. Try a different effect from the dropdown, such as “whirl”or “fisheye.” Choose an effect you like. To make the effect keep happening, from the“control” menu, place a “repeat” loop around the “change effect by” block. Clickon it to watch what it does. Tinker with the values until you find something that worksfor you. Try combining different effects. Pretty cool.
Reverse the effect by using the negative number opposite to the positive number you used,repeated the same number of times. In this example, the sprite changes the fisheye effectby 2 and the color effect by 10, 10 times. Duplicate the the block stack, and put a negativesign in front of each of the numbers. Test it. The background expands then contracts,changing colors the whole time. Great. To return the background to how it lookedwith no effects, from the “looks” menu, use the “clear graphic effects” block.
To clear the background of effects when the green flag is clicked, place this block beforethe “change effect by” blocks. Then, from the “events” menu, place a “when flagclicked” block on the top of the stack. Here’s the gameplan:Change the backdrop graphics by clicking on the “stage” then using the “change effectby” block. Repeat the changed effects.
Clear the stage of all graphic effects when the flag is clicked.