Scratch

Paddle2See · 2012-02-08 15:39:22

A lot of the beginning projects I see often use this kind of simple sprite control:

when Up Arrow ▼
 key pressed
point in direction 0  ▼
move 10
 steps
when Down Arrow ▼
 key pressed
point in direction 180  ▼
move 10
 steps
when Right Arrow ▼
 key pressed
point in direction 90  ▼
move 10
 steps
when Left Arrow ▼
 key pressed
point in direction -90  ▼
move 10
 steps

Probably because it's in some of the sample projects and it's easy to understand.

The method above works...but it's kind of jerky for continuous movement. It takes some time after your finger presses a key for your computer to decide that you really want a repeated motion and starts to generate more key presses.

A better method (in most cases), uses a continuously scanning loop with key sensing to see if the key is pressed. The result is faster response and smoother motion. I've shown it with a variable called "Speed" defined because it's so handy to be able to tune the speed in one place instead of four.

when  clicked
set Speed ▼
 to 4
forever
if key Up Arrow ▼
 pressed?
point in direction 0  ▼
move Speed
 steps
if key Down Arrow ▼
 pressed?
point in direction 180  ▼
move Speed
 steps
if key Right Arrow ▼
 pressed?
point in direction 90  ▼
move Speed
 steps
if key Left Arrow ▼
 pressed?
point in direction -90  ▼
move Speed
 steps

Last edited by Paddle2See (2012-02-08 18:40:31)

TRocket · 2012-02-08 15:48:38

great guide smile i'm sure this will help a lot of new scratchers...

Last edited by TRocket (2012-02-08 15:54:00)

Magnie · 2012-02-08 15:52:32

Actually TRocket, he did it just fine. Technically it's supposed to be like this:

when  clicked
set Speed ▼
 to 4
forever
if key Up Arrow ▼
 pressed?
point in direction 0  ▼
move Speed
 steps
if key Down Arrow ▼
 pressed?
point in direction 180  ▼
move Speed
 steps
if key Right Arrow ▼
 pressed?
point in direction 90  ▼
move Speed
 steps
if key Left Arrow ▼
 pressed?
point in direction -90  ▼
move Speed
 steps

Last edited by Magnie (2012-02-08 15:53:00)

CheeseMunchy · 2012-02-08 17:18:25

Awesome.

RedRocker227 · 2012-02-08 17:42:21

Wow, my first ever project used the method with the hat blocks :') It's really annoying when I find a project which would he awesome, but it uses the method with the hat blocks, so then you can't move properly :l

Paddle2See · 2012-02-08 18:42:12

Magnie wrote:
Actually TRocket, he did it just fine. Technically it's supposed to be like this:

Thanks smile

Fixed.

Jupitar · 2012-06-06 03:04:03

Great tutorial! In many New Scratcher projects, I see the basic jump down"formulae" and the sprite hangs in mid-air. I'm sure it was based on a sample project, where the sprite hangs in mid-air and drops down again?

sonicfan12p · 2012-06-06 09:10:07

Good guide, this should come in handy for New Scratchers! smile

humhumgames · 2012-06-06 14:05:22

This will be very helpful to new scratchers.

fetzer · 2012-06-06 17:23:39

*Request to be stickied*

Scratch

archived forums

#1 2012-02-08 15:39:22

Tutorial: Simple Arrow-key Controlled Sprite Motion

#2 2012-02-08 15:48:38

Re: Tutorial: Simple Arrow-key Controlled Sprite Motion

#3 2012-02-08 15:52:32

Re: Tutorial: Simple Arrow-key Controlled Sprite Motion

#4 2012-02-08 17:18:25

Re: Tutorial: Simple Arrow-key Controlled Sprite Motion

#5 2012-02-08 17:42:21

Re: Tutorial: Simple Arrow-key Controlled Sprite Motion

#6 2012-02-08 18:42:12

Re: Tutorial: Simple Arrow-key Controlled Sprite Motion

Magnie wrote:

#7 2012-06-06 03:04:03

Re: Tutorial: Simple Arrow-key Controlled Sprite Motion

#8 2012-06-06 09:10:07

Re: Tutorial: Simple Arrow-key Controlled Sprite Motion

#9 2012-06-06 14:05:22

Re: Tutorial: Simple Arrow-key Controlled Sprite Motion

#10 2012-06-06 17:23:39

Re: Tutorial: Simple Arrow-key Controlled Sprite Motion

Board footer