User Guide

101
5.2 The Level Backgrounds
Scrolling is an effect where the background of a game moves in
the opposite direction to the player. This makes it look like the
player’s character is moving when they are actually standing still.
However, Scratch cannot move the project background so your
scrolling has to be created using sprites. But it has two further
restrictions that make this complicated:
• Sprites cannot move completely off the Stage; and
• The maximum size of a sprite is 480 steps x 360 steps.
You cannot use one sprite for the entire background.
Preparing the Background Sprites
You can find images of the NES version of Double Dragon® on
The Spriters Resource (http://www.spriters-resource.com). To
use this background, you need to make it twice as large – 2030
pixels wide and 384 pixels tall. Then you will have to trim off 24
pixels from the top.
Scratch’s Paint Editor is not ideal for working with large files, so
you should use a different paint editor, such as Adobe
Photoshop, Microsoft Paint, or KolourPaint.
Next, you need to divide the background into four images that
measure 480px by 360px and one image that measures 110px
by 360px. Save each piece to its own file in portable network
graphics (PNG) format.
Figure 2. The five background sprites. Original artwork ©1987 Technos Japan Corp.
If you are using Adobe Photoshop: when resizing the image, next
to Resample Image click Bicubic and then click Nearest Neighbor.