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Index › Programming Questions & Help › Programs › simple easing motion
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simple easing motion (Read 367 times)
Kasai
simple easing motion
Mar 19th, 2009, 5:21am  
I am writing some very simple code that moves
a circle up, left, right, and down using the arrow
keys as input. The code that sets the x and y velocity
is here:

void keyPressed(){
   if( key == CODED)
   {
     if(keyCode == UP){
       yVel=-3;
     }
     if(keyCode == DOWN){
       yVel=3;
     }
     if(keyCode == LEFT){
       xVel=-3;
     }
     if(keyCode == RIGHT){
       xVel=3;
     }
   }
}

I also have a few lines of code that creates the "easing" effect by reducing the velocities by a certain amount each time draw runs, as well as updating the position based on the velocities:

xVel=xVel*0.94;
yVel=yVel*0.94;
posX+=xVel;
posY+=yVel;
ellipse(posX,posY,10,10);

My issue with this is that the code works fine for the left and up arrow keys (negative values of xVel or yVel), but the circle barely even moves to the right or up. The code seems like it should work properly, but I am stuck now.

Any help you could give me would be great.
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RickiG
Re: simple easing motion
Reply #1 - Mar 19th, 2009, 8:41am  
I just copy-pasted your code, it seems to work just fine here?
All I did extra was to declare all the variables as float:

float xVel;
float yVel;
float posX;
float posY;

void keyPressed(){  
   if( key == CODED)
   {
if(keyCode == UP){
  yVel=-3;
}
if(keyCode == DOWN){
  yVel=3;
}
if(keyCode == LEFT){
  xVel=-3;
}
if(keyCode == RIGHT){
  xVel=3;
}
   }
}
void draw()
{
xVel=xVel*0.94;
yVel=yVel*0.94;
posX+=xVel;
posY+=yVel;
ellipse(posX,posY,10,10);
}
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Regards Ricki
 
Kasai
Re: simple easing motion
Reply #2 - Mar 19th, 2009, 1:55pm  
You're right that does work. I don't know why I was getting the results I received before. I'll just rewrite this section and see what happens. Thanks.
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RickiG
Re: simple easing motion
Reply #3 - Mar 19th, 2009, 2:29pm  
No need to thank me, you didn't need my help Wink
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Regards Ricki
 
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