Game Development Reference
In-Depth Information
Engage thrusters
For the scrolling background, we will need two idenical images with slightly diferent scripts.
The easiest way to create this is to write one script first. Then, copy the image including the
script and make the necessary changes.
1. Start with a when <green lag> clicked block.
2. Define a variable called speedMultiplier . Remember that the buton to do this
is in the Data category. This variable should be for this sprite only.
3. Enter 0.5 in the set <speedMuliplier> to () block.
4. Make the image go back 100 layers by entering 100 in the go back () layers block.
We just use a suitably high number so that the image is placed behind all other
sprites on the stage.
5. Then, we posiion the image to its staring point with the go to x: () y: () block; enter
-240 and 0 respecively. So the center of the image is at the let edge of the stage.
6. We add a forever loop, which will contain the movement script.
7. First we need another variable called scrollingSpeed . This variable should be
for all sprites. We will use it as a base speed value.
8. At each step of the loop, change x by () . The blank slot will take a value that sill has
to be determined.
9. Here we include a calculaion— scrollingSpeed * speedMuliplier . We use the
muliplier to slow down the background image compared to the scrolling speed
of the base. Remember we set it to 0.5 so the background will move at half of
the speed.
When the image has scrolled completely out of view, we have to reset it to the right of the
stage so that it can scroll in again. To do this, we check where the image is. Also, if it has
reached a certain limit, we move it to the right of the stage.
1. We place an if () then condiion check underneath the change x by () block.
2. Inside the condiion, we check whether x posiion (from the Moion category)
is less than -460 by entering -460 in the x posiion < () block.
 
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