缩放相当简单,只需设置主游戏图层的缩放属性...但有一些问题。
当您缩放图层时,它会移动图层的位置。它不会自动缩放到您当前正在查看的内容的中心。如果您的游戏中有任何类型的滚动,则需要考虑到这一点。
为此,请设置anchorPoint
你的图层到ccp(0.0f, 0.0f)
,然后计算图层移动了多少,并相应地重新定位。
- (void) scale:(CGFloat) newScale scaleCenter:(CGPoint) scaleCenter {
// scaleCenter is the point to zoom to..
// If you are doing a pinch zoom, this should be the center of your pinch.
// Get the original center point.
CGPoint oldCenterPoint = ccp(scaleCenter.x * yourLayer.scale, scaleCenter.y * yourLayer.scale);
// Set the scale.
yourLayer.scale = newScale;
// Get the new center point.
CGPoint newCenterPoint = ccp(scaleCenter.x * yourLayer.scale, scaleCenter.y * yourLayer.scale);
// Then calculate the delta.
CGPoint centerPointDelta = ccpSub(oldCenterPoint, newCenterPoint);
// Now adjust your layer by the delta.
yourLayer.position = ccpAdd(yourLayer.position, centerPointDelta);
}
捏缩放更容易...只需检测touchesMoved,然后调用您的缩放例程。
- (void) ccTouchesMoved:(NSSet*)touches withEvent:(UIEvent*)event {
// Examine allTouches instead of just touches. Touches tracks only the touch that is currently moving...
// But stationary touches still trigger a multi-touch gesture.
NSArray* allTouches = [[event allTouches] allObjects];
if ([allTouches count] == 2) {
// Get two of the touches to handle the zoom
UITouch* touchOne = [allTouches objectAtIndex:0];
UITouch* touchTwo = [allTouches objectAtIndex:1];
// Get the touches and previous touches.
CGPoint touchLocationOne = [touchOne locationInView: [touchOne view]];
CGPoint touchLocationTwo = [touchTwo locationInView: [touchTwo view]];
CGPoint previousLocationOne = [touchOne previousLocationInView: [touchOne view]];
CGPoint previousLocationTwo = [touchTwo previousLocationInView: [touchTwo view]];
// Get the distance for the current and previous touches.
CGFloat currentDistance = sqrt(
pow(touchLocationOne.x - touchLocationTwo.x, 2.0f) +
pow(touchLocationOne.y - touchLocationTwo.y, 2.0f));
CGFloat previousDistance = sqrt(
pow(previousLocationOne.x - previousLocationTwo.x, 2.0f) +
pow(previousLocationOne.y - previousLocationTwo.y, 2.0f));
// Get the delta of the distances.
CGFloat distanceDelta = currentDistance - previousDistance;
// Next, position the camera to the middle of the pinch.
// Get the middle position of the pinch.
CGPoint pinchCenter = ccpMidpoint(touchLocationOne, touchLocationTwo);
// Then, convert the screen position to node space... use your game layer to do this.
pinchCenter = [yourLayer convertToNodeSpace:pinchCenter];
// Finally, call the scale method to scale by the distanceDelta, pass in the pinch center as well.
// Also, multiply the delta by PINCH_ZOOM_MULTIPLIER to slow down the scale speed.
// A PINCH_ZOOM_MULTIPLIER of 0.005f works for me, but experiment to find one that you like.
[self scale:yourlayer.scale - (distanceDelta * PINCH_ZOOM_MULTIPLIER)
scaleCenter:pinchCenter];
}
}