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ipad:如何通过滑动来移动精灵,并根据滑动速度继续移动

iphone-sdk-3.2 cocos2d-iphone ipad

0

Sadat · 技术社区 · 15 年前

我有一个精灵(球的形象),我可以移动它使用触摸和移动。我还确定了位置(x轴,y轴)的变化率取决于滑动周期。

现在我需要继续这个精灵按照它的速度和方向前进。这是我的密码-

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;
}

虽然,目前我正在使用静态速度调整技术,但我希望使其动态取决于初始速度(我欣赏任何想法)

2 回复 | 直到 15 年前

1

0

cc. 15 年前

看起来你已经很接近了。你在触摸端安排一个选择器,计算速度,然后根据这个速度移动精灵,直到它衰减,所以所有的机械部件都在那里。

看起来不确定的是物理学。例如,你在速度上做了一些奇怪的事情来减缓球的速度,这看起来一点都不现实。

 float speed = sqrt( speedx * speedx + speedy * speedy );
 if (speed == 0) {
     // kill motion here, unschedule or do whatever you need to
 }
 // Dampen the speed.
 float newSpeed = speed * .9;
 if (newSpeed < SOME_THRESHOLD) newSpeed = 0;
 speedx = speedx * newSpeed / speed;
 speedy = speedy * newSpeed / speed;
 //  Move sprite according to the new speed

这将使球在释放时保持同一方向,逐渐减速直至停止。更多信息,特别是如果你想做一些反弹或什么,谷歌为向量代数介绍。

2

0

Sadat 15 年前

谢谢大家。

//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];

  }