Hi !
Featured games (84)
games approved by the League of Dukes
Games in Showcase (593)
Games in Android Showcase (168)
games submitted by our members
Games in WIP (646)
games currently in development
News: Read the Java Gaming Resources, or peek at the official Java tutorials
    Home     Help   Search   Login   Register   
Pages: [1]
  ignore  |  Print  
  Gradually slow an images movement.  (Read 1033 times)
0 Members and 1 Guest are viewing this topic.
Offline wreed12345

JGO Knight

Medals: 25
Projects: 2
Exp: 2 years

« Posted 2013-02-03 03:24:12 »

Right now i have just started a new game and i am controlling basic movement by this code:
      if ((Gdx.input.isKeyPressed(Keys.W)))
         levelY -= 5;
      if ((Gdx.input.isKeyPressed(Keys.A)))
         levelX += 5;
      if ((Gdx.input.isKeyPressed(Keys.S)))
         levelY += 5;
      if ((Gdx.input.isKeyPressed(Keys.D)))
         levelX -= 5;

Now when the keys aren't pressed the motion stops instantly so I was wondering if there was some formula I could use to gradually slow the movement or maybe not even a formula just another way of doing this. I thought this would be a somewhat discussed subject but my Google searching hasn't found anything. Thanks in advanced!

Online Phased
« Reply #1 - Posted 2013-02-03 03:32:51 »

By completely controlling the X and Y by inside the if pressed, you wont.

You would need to have a variable like up= true;

I have never done anything like this, so my first thought might not be a very good implementation of this, but here is a example.

y -= 5;
slowingDown = 5;
}else if(slowingDown > 0){
y -= slowingDown;

should slow down till it reaches 0. and the same for left, right and down. you could control it by time differences if you want it to slow down after a certain amount of time instead of after 5 updates.
Offline wreed12345

JGO Knight

Medals: 25
Projects: 2
Exp: 2 years

« Reply #2 - Posted 2013-02-03 03:38:57 »

Wow thank you! That was surprisingly simple. For some reason I thought this would be much more complex....

Games published by our own members! Check 'em out!
Legends of Yore - The Casual Retro Roguelike
Offline Best Username Ever

Junior Devvie

« Reply #3 - Posted 2013-02-03 04:12:16 »

Uh. That's kind of bad practice. You should base your game mechanics on physics.

An object in motion stays in motion (Okay. It's already moving so I should not change an objects velocity.) unless acted upon by an outside force. (Okay. Friction is a force. I will use that.)

There are two types of friction. If you only care about coasting when the arrow key is released, then you only need to worry about kinetic friction. If you're moving across a solid surface, then friction is proportional to your speed. f = -k * x' = -k * v = -kinetic_friction_coefficient * speed. Force increases or (in this case) decreases speed in a given direction over time. So you just subtract more or less from the speed depending on the friction, which depends on the speed you are traveling.

if(right && !left)
  vx = 5;
else if(left && !right)
  vx = -5;
  vx -= 0.5 * vx;
x += vx;

If you wanted acceleration when the key is pressed, you would use vx += something instead of vx = something.

Changing k changes how slippery the surface is. A value of zero is frictionless, so you never lose speed. A value of 1 makes you stop instantaneously.
Offline Jimmt
« League of Dukes »

JGO Kernel

Medals: 161
Projects: 5
Exp: 3 years

« Reply #4 - Posted 2013-02-03 04:32:01 »

yes, this kind of stuff is all about velocity (how did google not return anything Huh)
Just think of a vector pointing in the direction of the image's movement, and the slow down the speed. Thinking with vectors in libgdx makes things a lot easier.
Pages: [1]
  ignore  |  Print  
You cannot reply to this message, because it is very, very old.

Riven (16 views)
2015-07-03 11:22:16

deepthought (44 views)
2015-06-30 15:39:44

deepthought (48 views)
2015-06-30 15:39:09

deepthought (59 views)
2015-06-30 15:36:52

Za\'Anzabar (28 views)
2015-06-29 05:44:54

TritonDreyja (44 views)
2015-06-24 17:10:40

CopyableCougar4 (43 views)
2015-06-23 00:34:45

BurntPizza (46 views)
2015-06-21 20:36:46

cookiecompiler (88 views)
2015-06-11 15:42:53

cookiecompiler (51 views)
2015-06-11 15:41:14
How Do I Expand My Game?
by bashfrog
2015-06-14 11:34:43

List of Learning Resources
by PocketCrafter7
2015-05-31 05:37:30

Intersection Methods
by Roquen
2015-05-29 08:19:33

List of Learning Resources
by SilverTiger
2015-05-05 10:20:32

How to: JGO Wiki
by Mac70
2015-02-17 20:56:16

2D Dynamic Lighting
by ThePixelPony
2015-01-01 20:25:42

How do I start Java Game Development?
by gouessej
2014-12-27 19:41:21

Resources for WIP games
by kpars
2014-12-18 10:26:14 is not responsible for the content posted by its members, including references to external websites, and other references that may or may not have a relation with our primarily gaming and game production oriented community. inquiries and complaints can be sent via email to the info‑account of the company managing the website of java‑
Powered by MySQL Powered by PHP Powered by SMF 1.1.18 | SMF © 2013, Simple Machines | Managed by Enhanced Four Valid XHTML 1.0! Valid CSS!