Java-Gaming.org Hi !
 Featured games (90) games approved by the League of Dukes Games in Showcase (789) Games in Android Showcase (234) games submitted by our members Games in WIP (864) games currently in development
 News: Read the Java Gaming Resources, or peek at the official Java tutorials
Pages: [1]
 ignore  |  Print
 Gradually slow an images movement.  (Read 2537 times) 0 Members and 1 Guest are viewing this topic.
wreed12345

JGO Knight

Medals: 28
Projects: 3
Exp: 5 years

https://github.com/william-reed

 « 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:
 1  2  3  4  5  6  7  8 `      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!

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.

 1  2  3  4  5  6  7 `if(up){y -= 5;slowingDown = 5;}else if(slowingDown > 0){y -= slowingDown;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.
wreed12345

JGO Knight

Medals: 28
Projects: 3
Exp: 5 years

https://github.com/william-reed

 « 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....

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.

 1  2  3  4  5  6  7  8  9  10  11  12  13 `if(right && !left){  vx = 5;} else if(left && !right){  vx = -5;}else{  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.
Jimmt
« League of Dukes »

JGO Kernel

Medals: 167
Projects: 5
Exp: 6 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 )
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

 hadezbladez (2631 views) 2018-11-16 13:46:03 hadezbladez (950 views) 2018-11-16 13:41:33 hadezbladez (2590 views) 2018-11-16 13:35:35 hadezbladez (510 views) 2018-11-16 13:32:03 EgonOlsen (3744 views) 2018-06-10 19:43:48 EgonOlsen (4140 views) 2018-06-10 19:43:44 EgonOlsen (2496 views) 2018-06-10 19:43:20 DesertCoockie (3304 views) 2018-05-13 18:23:11 nelsongames (3400 views) 2018-04-24 18:15:36 nelsongames (4378 views) 2018-04-24 18:14:32
 cygnus 15x Spasi 12x SkyAphid 12x orange451 12x FabulousFellini 9x KaiHH 8x VaTTeRGeR 8x philfrei 7x NuclearPixels 5x BitBotz 5x SHC 5x Speiger 4x elect 3x orangepascal 3x yboya 2x Ecumene 2x
 Java Gaming Resourcesby philfrei2019-05-14 16:15:13Deployment and Packagingby philfrei2019-05-08 15:15:36Deployment and Packagingby philfrei2019-05-08 15:13:34Deployment and Packagingby philfrei2019-02-17 20:25:53Deployment and Packagingby mudlee2018-08-22 18:09:50Java Gaming Resourcesby gouessej2018-08-22 08:19:41Deployment and Packagingby gouessej2018-08-22 08:04:08Deployment and Packagingby gouessej2018-08-22 08:03:45
 java-gaming.org 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‑gaming.org