Question

I have a sprite(image of a ball) I can move it using touch and move. I have also identified the rate of change of location(x-axis,y-axis) of that sprite depending on sliding period.

Now I need to continue that sprite to go according to its speed and direction. Here is my code-

Touch Event

- (BOOL)ccTouchBegan:(UITouch *)touch withEvent:(UIEvent *)event {

  CGPoint location = [touch locationInView: [touch view]];
  CGPoint convertedLocation = [[CCDirector sharedDirector] convertToGL:location];

  self.touchStartTime = [event timestamp];
  self.touchStartPosition = location;

  if (YES == [self isItTouched:self.striker touchedAt:convertedLocation]) {
    self.striker.isInTouch = YES;
  }

  return YES;
}

- (void)ccTouchMoved:(UITouch *)touch withEvent:(UIEvent *)event {

  CGPoint location = [touch locationInView: [touch view]];
  CGPoint convertedLocation = [[CCDirector sharedDirector] convertToGL:location];

  self.touchLastMovedTime = [event timestamp];
  self.touchMovedPosition = convertedLocation;


  if(self.striker.isInTouch == YES){
    self.striker.position = self.touchMovedPosition;
  }

}
- (void)ccTouchEnded:(UITouch *)touch withEvent:(UIEvent *)event {

  CGPoint location = [touch locationInView: [touch view]];
  CGPoint convertedLocation = [[CCDirector sharedDirector] convertToGL:location];

  self.touchEndTime = [event timestamp];
  self.touchEndPosition = location;

  if( self.striker.isInTouch == YES 
    && ( self.touchEndTime - self.touchLastMovedTime ) <= MAX_TOUCH_HOLD_DURATION )
  {
    float c = sqrt( pow( self.touchStartPosition.x - self.touchEndPosition.x, 2 ) 
        + pow( self.touchStartPosition.y - self.touchEndPosition.y, 2 ) );

    self.striker.speedx =  ( c - ( self.touchStartPosition.y - self.touchEndPosition.y ) ) 
                         / ( ( self.touchEndTime - self.touchStartTime ) * 1000 );

    self.striker.speedy =  ( c - ( self.touchStartPosition.x - self.touchEndPosition.x ) ) 
             / ( ( self.touchEndTime -   self.touchStartTime ) * 1000 );

    self.striker.speedx *= 4;
    self.striker.speedy *= 4;

    self.striker.isInTouch = NO;
    [self schedule:@selector( nextFrame ) interval:0.001];

  }

}

Scheduled Method to move Sprite

- (void) nextFrame {

  [self setPieceNextPosition:self.striker];
  [self adjustPieceSpeed:self.striker];

  if( abs( self.striker.speedx ) <= 1 && abs( self.striker.speedy ) <= 1 ){
    [self unschedule:@selector( nextFrame )];
  }
}

SET next Position

- (void) setPieceNextPosition:(Piece *) piece{

  CGPoint nextPosition;
  float tempMod;
  tempMod = ( piece.position.x + piece.speedx ) / SCREEN_WIDTH;
  tempMod = (tempMod - (int)tempMod)*SCREEN_WIDTH;
  nextPosition.x = tempMod;

  tempMod = ( piece.position.y + piece.speedy ) / SCREEN_HEIGHT;
  tempMod = (tempMod - (int)tempMod)*SCREEN_HEIGHT;
  nextPosition.y = tempMod;

  piece.position = nextPosition;
}

Set new Speed

- (void) adjustPieceSpeed:(Piece *) piece{

  piece.speedx =(piece.speedx>0)? piece.speedx-0.05:piece.speedx+0.05;
  piece.speedy =(piece.speedy>0)? piece.speedy-0.05:piece.speedy+0.05;
}

Though, currently I am using static speed adjusting technique, but I hope to make it dynamic depending on initial speed( I appreciate any idea)

Answer 1

thanks @all.
I have got my solution as below-

//in adjustSpeed method
  piece.speedx -= piece.speedx * DEACCLERATION_FACTOR;
  piece.speedy -= piece.speedy * DEACCLERATION_FACTOR;

//and simply, free the sprite to move from ccTouchMoved method not ccTouchEnd
  if(self.striker.isInTouch == YES && distance_passed_from_touch_start>=a_threashold){
    //calculate speed and position here as it was in ccTouchEnd method
    self.striker.isInTouch = NO;
    [self schedule:@selector( nextFrame ) interval:0.001];

  }