I have looked at this post and rickster's answer and lorenzo's sample code
Lorenzo's code works well. I am trying to extend it and add a conventional pan where you can move the scene left, right, up and down.
Here is what I have tried:
-(void) handlePan2F :(UIPanGestureRecognizer*)recognizer {
CGPoint translation = [recognizer translationInView:recognizer.view];
CGFloat xVal = translation.x * 0.025 ; // apply some damping
CGFloat yVal = translation.y * 0.025 ;
if (recognizer.state == UIGestureRecognizerStateChanged) {
self.cameraOrbit.position = SCNVector3Make(-xVal, yVal ,0.0); // what should the value be for z?
}
}
The issues I am running into are:
The pan works kind of - but not well.
If I add a SCNLookAtConstraint to point an area in the scene then the
pan2F gesture rotates the scene. Why is that?
The behavior I am trying to implement is to just to pan left/right/up down over the scene without any scene rotation. How to fix this code?
I am willing to give up SCNLookAtConstraint as long as I can zoom to a specific area within the scene.
Related
I'm using a UIPanGestureRecognizer and UIAttachmentBehavior to move a UIView around the screen. When the user ends the gesture I apply the velocity of the gesture recognizer to the view using a UIDynamicItemBehavior and the addLinearVelocity:forItem: method.
Here is the code I use:
- (void)_handlePanGestureRecognized: (UIPanGestureRecognizer *)panGestureRecognizer
{
if (panGestureRecognizer.state == UIGestureRecognizerStateBegan)
{
_attachmentBehavior.anchorPoint = panGestureRecognizer.view.center;
[_dynamicAnimator addBehavior: _attachmentBehavior];
}
else if (panGestureRecognizer.state == UIGestureRecognizerStateChanged)
{
CGPoint point = [panGestureRecognizer locationInView: panGestureRecognizer.view.superview];
_attachmentBehavior.anchorPoint = point;
}
else if (panGestureRecognizer.state == UIGestureRecognizerStateEnded)
{
[_dynamicAnimator removeBehavior: _attachmentBehavior];
CGPoint velocity = [panGestureRecognizer velocityInView: panGestureRecognizer.view.superview];
[_dynamicItemBehavior addLinearVelocity: velocity
forItem: self];
}
}
When the view stops moving I would then like to have it snap to the closest edge of the screen but I currently have no way of knowing when it has stopped moving short of polling the view's center with a CADisplayLink.
Have you tried attaching a UIDynamicAnimatorDelegate to your animator, and using the dynamicAnimatorDidPause: method to trigger snapping to the closest edge?
From reading on the developer forums, it sounds like some have had problems with their views staying in motion for a very long time (jiggling back and forth by 1 pixel, for example), but perhaps this will work for your case.
Update: Though I'd still like to solve this, I ended up switching to animateWithDuration:delay:options:animations:completion: and it works much nicer. It's missing that nice "bounce" at the end that the spring affords, but at least it's controllable.
I am trying to create a nice gesture-driven UI for iOS but am running into some difficulties getting the values to result in a nice natural feeling app.
I am using animateWithDuration:delay:usingSpringWithDamping:initialSpringVelocity:options:animations:completion: because I like the bouncy spring animation. I am initializing the velocity argument with the velocity as given by the gesture recognizer in the completed state. The problem is if I pan quickly enough and let go, the velocity is in the thousands, and my view ends up flying right off the screen and then bouncing back and forth with such dizzying vengeance.
I'm even adjusting the duration of the animation relative to the amount of distance the view needs to move, so that if there are only a few pixels needed, the animation will take less time. That, however, didn't solve the issue. It still ends up going nuts.
What I want to happen is the view should start out at whatever velocity the user is dragging it at, but it should quickly decelerate when reaching the target point and only bounce a little bit at the end (as it does if the velocity is something reasonable).
I wonder if I am using this method or the values correctly. Here is some code to show what I'm doing. Any help would be appreciated!
- (void)handlePanGesture:(UIPanGestureRecognizer*)gesture {
CGPoint offset = [gesture translationInView:self.view];
CGPoint velocity = [gesture velocityInView:self.view];
NSLog(#"pan gesture state: %d, offset: %f velocity: %f", gesture.state, offset.x, velocity.x);
static CGFloat initialX = 0;
switch ( gesture.state ) {
case UIGestureRecognizerStateBegan: {
initialX = self.blurView.x;
break; }
case UIGestureRecognizerStateChanged: {
self.blurView.x = initialX + offset.x;
break; }
default:
case UIGestureRecognizerStateCancelled:
case UIGestureRecognizerStateEnded: {
if ( velocity.x > 0 )
[self openMenuWithVelocity:velocity.x];
else
[self closeMenuWithVelocity:velocity.x];
break; }
}
}
- (void)openMenuWithVelocity:(CGFloat)velocity {
if ( velocity < 0 )
velocity = 1.5f;
CGFloat distance = -40 - self.blurView.x;
CGFloat distanceRatio = distance / 260;
NSLog(#"distance: %f ratio: %f", distance, distanceRatio);
[UIView animateWithDuration:(0.9f * distanceRatio) delay:0 usingSpringWithDamping:0.7 initialSpringVelocity:velocity options:UIViewAnimationOptionBeginFromCurrentState animations:^{
self.blurView.x = -40;
} completion:^(BOOL finished) {
self.isMenuOpen = YES;
}];
}
Came across this post while looking for a solution to a related issue. The problem is, you're passing in the velocity from UIPanGestureRecognizer, which is in points/second, when - animateWithDuration:delay:usingSpringWithDamping:initialSpringVelocity:options:animations:completion wants… a slightly odder value:
The initial spring velocity. For smooth start to the animation, match this value to the view’s velocity as it was prior to attachment.
A value of 1 corresponds to the total animation distance traversed in one second. For example, if the total animation distance is 200 points and you want the start of the animation to match a view velocity of 100 pt/s, use a value of 0.5.
The animation method wants velocity in "distances" per second, not points per second. So, the value you should be passing in is (velocity from the gesture recognizer) / (total distance traveled during the animation).
That said, that's exactly what I'm doing and there's still a slight, yet noticeable "hiccup" between when the gesture recognizer is moving it, and when the animation picks up. That said, it should still work a lot better than what you had before. 😃
First you need to calculate the remaining distance that the animation will have to take care of. When you have the delta distance you can proceed to calculate the velocity like this:
CGFloat springVelocity = fabs(gestureRecognizerVelocity / distanceToAnimate);
For clean velocity transfer you must use UIViewAnimationOptionCurveLinear.
I had a slightly different need, but my code may help, namely the velocity calculation, based on (pan velocity / pan translation).
A bit of context: I needed to use a panGestureRecognizer on the side of a UIView to resize it.
If the iPad is in portrait mode, the view is attached on the left, bottom
and right sides, and I drag on the top border of the view to resize
it.
If the iPad is in landscape mode, the view is attached to the
left, top and bottom sides, and I drag on the right border to resize it.
This is what I used in the IBAction for the UIPanGestureRecognizer:
var velocity: CGFloat = 1
switch gesture.state {
case .changed:
// Adjust the resizableView size according to the gesture translation
let translation = gesture.translation(in: resizableView)
let panVelocity = gesture.velocity(in: resizableView)
if isPortrait { // defined previously in the class based on UIDevice orientation
let newHeight = resizableViewHeightConstraint.constant + (-translation.y)
resizableViewHeightConstraint.constant = newHeight
// UIView animation initialSpringVelocity requires a velocity based on the total distance traveled during the animation
velocity = -panVelocity.y / -panTranslation.y
} else { // Landscape
let newWidth = resizableViewWidthConstraint.constant + (translation.x)
// Limit the resizing to half the width on the left and the full width on the right
resizableViewWidthConstraint.constant = min(max(resizableViewInitialSize, newWidth), self.view.bounds.width)
// UIView animation initialSpringVelocity requires a velocity based on the total distance traveled during the animation
velocity = panVelocity.x / panTranslation.x
}
UIView.animate(withDuration: 0.5,
delay: 0,
usingSpringWithDamping: 1,
initialSpringVelocity: velocity,
options: [.curveEaseInOut],
animations: {
self.view.layoutIfNeeded()
},
completion: nil)
// Reset translation
gesture.setTranslation(CGPoint.zero, in: resizableView)
}
Hope that helps.
I have a pan gesture recogniser acting as a slider, code as follows:
- (void)minutePan:(UIPanGestureRecognizer *)gesture
{
if ((gesture.state == UIGestureRecognizerStateChanged) ||
(gesture.state == UIGestureRecognizerStateEnded)){
CGPoint translation = [gesture translationInView:gesture.view.superview];
float leftBound = gesture.view.bounds.size.width / 2.0f;
float rightBound = gesture.view.bounds.size.width + (leftBound - 60);
float position;
if(gesture.view.center.x < leftBound){
position = leftBound;
}else if(gesture.view.center.x > rightBound){
position = rightBound;
}else{
position = gesture.view.center.x + translation.x;
}
gesture.view.center = CGPointMake(position, gesture.view.center.y);
[gesture setTranslation:CGPointZero inView:gesture.view.superview];
}
}
I have a UIView with the gesture recogniser attached inside another UIView acting as the boundary for it. Its working fine except when I get to the left and right edges. The position variable should not get set lower than half the panned views width but it seems to be updating the view on the screen before the code runs. This causes the view to go outside the bounds and flicker back as long as the user is dragging. Any help would be greatly appreciated thanks.
Essentially, what I want to do is to move a view around to follow the user's pan. This works fine as long as the same pan object is being used. The problem comes when the user releases and than starts another pan.
According to the documentation, the value in translationInView is relative to the position at the start of the pan.
So my strategy for handling this was to add two properties to my view so I can tell whether the same pan object is being used and what the reference location is. The self object is the object being moved. It is a UIView subclass.
CGPoint originalPoint;
if (pan == self.panObject) {
//If the pan object is the same as the one in the property, use the saved value as the reference point.
originalPoint = CGPointMake(self.panStartLocation.x, self.panStartLocation.y);
} else {
//If the pan object is DIFFERENT, set the originalPoint from the existing center.
//self.center is in self.superview's coordinate system.
originalPoint = CGPointMake(self.center.x, self.center.y);
self.panStartLocation = CGPointMake(originalPoint.x, originalPoint.y);
self.panObject = pan;
}
CGPoint translation = [pan translationInView:self.superview];
self.center = CGPointMake(originalPoint.x+translation.x, originalPoint.y+translation.y);
This scheme doesn't work because each pan object apparently is the same object. I've spent a bit of time in the debugger verifying this, and that seems to be true. I thought the pan object would be different for each touch. So since this doesn't work, what is the alternative?
I solved it. Here is the corrected code:
CGPoint originalPoint;
if (pan.state == UIGestureRecognizerStateBegan) {
originalPoint = CGPointMake(self.center.x, self.center.y);
self.panStartLocation = CGPointMake(originalPoint.x, originalPoint.y);
} else {
originalPoint = CGPointMake(self.panStartLocation.x, self.panStartLocation.y);
}
CGPoint translation = [pan translationInView:self.superview];
self.center = CGPointMake(originalPoint.x+translation.x, originalPoint.y+translation.y);
EDIT: A better approach is to take advantage of the fact that the gesture recognizer allows you to set the translation:
[sender setTranslation:CGPointMake(0.0, 0.0) inView:self.pieceBeingMoved];
Do this when you move your item, and then the new translation next time will be relative to the position you just moved to.
in my app I have a UIImageView representing a chalk. The user can pick that up and drag it over the screen to draw with it.
I implemented that using touchesBegan, touchesMoved and touchesEnded. In touchesMoved I move the center of my UIImageView to the current touch location and draw a line with core graphics from the last to the current location.
This works well but the image view movement isn't very smooth and it also lags behind the touch. I already tried to use a UIPanGestureRecognizer (didn't recognize the gesture) and a UIScrollView in which I placed the chalk (didn't really figure out how to configure it so that it could be moved far enough in all directions).
Can you give me some hints how to improve the quality of my chalk movement?
Thanks!
The following tapGesture method method works smooth for me:
- (void)handlePan:(UIPanGestureRecognizer*)gesture{
View* view = (View*)gesture.view;
if (gesture.state == UIGestureRecognizerStateEnded){
view.dragStartingPoint = CGPointZero;
return;
}
CGPoint point = [gesture locationInView:gesture.view];
if (gesture.state == UIGestureRecognizerStateBegan){
view.dragStartingPoint = point;
view.dragStartingFrame = view.frame;
return;
}
if (CGPointEqualToPoint(view.dragStartingPoint, CGPointZero))
return;
CGFloat x = view.dragVerticallyOnly? view.frame.origin.x: view.dragStartingFrame.origin.x + point.x - view.dragStartingPoint.x;
CGFloat y = view.dragHorizontallyOnly? view.frame.origin.y: view.dragStartingFrame.origin.y + point.y - view.dragStartingPoint.y;
if (self.dragVerticallyOnly == NO){
if (x < view.dragMinPoint.x){
x = view.dragMinPoint.x;
}
else if (x > self.dragMaxPoint.x){
x = view.dragMaxPoint.x;
}
}
if (self.dragHorizontallyOnly == NO){
if (y < view.dragMinPoint.y){
y = view.dragMinPoint.y;
}
else if (y > self.dragMinPoint.y){
y = view.dragMinPoint.y;
}
}
CGFloat deltaX = x - view.frame.origin.x;
CGFloat deltaY = y - view.frame.origin.y;
if ((fabs(deltaX) <= 1.0 && fabs(deltaY) <= 1.0))
return; // Ignore very small movements
[UIView animateWithDuration:0.1 animations:^{
view.frame = CGRectMake(x, y, view.frame.size.width, view.frame.size.height);
}];
}
The most important points are:
Make the movement with the animated option; (one tenth of a second seems to do the job well done).
Avoid making movements when not necessary. Making some calculations will not make it slower, but making unnecessary movements might. However you cannot avoid to many movements otherwise it will not follow the user pan gesture.
Depending on how you want your view to behave, there can be more optimisations that you may want to make.
Remark: My method also takes into account boundaries and movement directions limits that you may define in case you need it. For instance, in my case I added a speed limit. If the user goes beyond a certain pan speed I just ignore further pan gestures and move the view (animated) where the user was pointing to, and at that speed. It may or not make sense in same cases. In mine, it did!
I hope I have been of some help!
look at this component : spuserresizableview
http://cocoacontrols.com/platforms/ios/controls/spuserresizableview
The source code is very simple and can help you to understand the view handling.
Try reducing the size of the Chalk image u are using....
Edited: By size i meant the image file size.
It helped me when i faced similar issue.
I rewrote how the movement is calculated and it is a little smoother now. Not perfect, but it's enough.