I want o move the UIImageView along a Bezier path, can anybody point me towards from where i can learn and achieve it.
An exact answer to that is probably very hard to do. But you may get close to what you want by using two CALayers, one a sublayer of the other. Put a x-translation animation on the one layer, and an y-translation animation on the other. Then experiment with custom animation timing functions for each of the translations.
See Animations Types and Timing Programming Guide
Related
I need to be able to interact with a representation of a cilinder that has many different parts in it. When the users taps over on of the small rectangles, I need to display a popover related to the specific piece (form).
The next image demonstrates a realistic 3d approach. But, I repeat, I need to solve the problem, the 3d is NOT required (would be really cool though). A representation that complies the functional needs will suffice.
The info about the parts to make the drawing comes from an API (size, position, etc)
I dont need it to be realistic really. The simplest aproximation would be to show a cilinder in a 2d representation, like a rectangle made out of interactable small rectangles.
So, as I mentioned, I think there are (as I see it) two opposite approaches: Realistic or Simplified
Is there a way to achieve a nice solution in the middle? What libraries, components, frameworks that I should look into?
My research has led me to SceneKit, but I still dont know if I will be able to interact with it. Interaction is a very important part as I need to display a popover when the user taps on any small rectangle over the cylinder.
Thanks
You don't need any special frameworks to achieve an interaction like this. This effect can be achieved with standard UIKit and UIView and a little trigonometry. You can actually draw exactly your example image using 2D math and drawing. My answer is not an exact formula but involves thinking about how the shapes are defined and break the problem down into manageable steps.
A cylinder can be defined by two offset circles representing the end pieces, connected at their radii. I will use an orthographic projection meaning the cylinder doesn't appear smaller as the depth extends into the background (but you could adapt to perspective if needed). You could draw this with CoreGraphics in a UIView drawRect.
A square slice represents an angle piece of the circle, offset by an amount smaller than the length of the cylinder, but in the same direction, as in the following diagram (sorry for imprecise drawing).
This square slice you are interested in is the area outlined in solid red, outside the radius of the first circle, and inside the radius of the imaginary second circle (which is just offset from the first circle by whatever length you want the slice).
To draw this area you simply need to draw a path of the outline of each arc and connect the endpoints.
To check if a touch is inside one of these square slices:
Check if the touch point is between angle a from the origin at a.
Check if the touch point is outside the radius of the inside circle.
Check if the touch point is inside the radius of the outside circle. (Note what this means if the circles are more than a radius apart.)
To find a point to display the popover you could average the end points on the slice or find the middle angle between the two edges and offset by half the distance.
Theoretically, doing this in Scene Kit with either SpriteKit or UIKit Popovers is ideal.
However Scene Kit (and Sprite Kit) seem to be in a state of flux wherein nobody from Apple is communicating with users about the raft of issues folks are currently having with both. From relatively stable and performant Sprite Kit in iOS 8.4 to a lot of lost performance in iOS 9 seems common. Scene Kit simply doesn't seem finished, and the documentation and community are both nearly non-existent as a result.
That being said... the theory is this:
Material IDs are what's used in traditional 3D apps to define areas of an object that have different materials. Somehow these Material IDs are called "elements" in SceneKit. I haven't been able to find much more about this.
It should be possible to detect the "element" that's underneath a touch on an object, and respond accordingly. You should even be able to change the state/nature of the material on that element to indicate it's the currently selected.
When wanting a smooth, well rounded cylinder as per your example, start with a cylinder that's made of only enough segments to describe/define the material IDs you need for your "rectangular" sections to be touched.
Later you can add a smoothing operation to the cylinder to make it round, and all the extra smoothing geometry in each quadrant of unique material ID should be responsive, regardless of how you add this extra detail to smooth the presentation of the cylinder.
Idea for the "Simplified" version:
if this representation is okey, you can use a UICollectionView.
Each cell can have a defined size thanks to
collectionView:layout:sizeForItemAtIndexPath:
Then each cell of the collection could be a small rectangle representing a
touchable part of the cylinder.
and using
collectionView:(UICollectionView *)collectionView
didSelectItemAtIndexPath:(NSIndexPath *)indexPath
To get the touch.
This will help you to display the popover at the right place:
CGRect rect = [collectionView layoutAttributesForItemAtIndexPath:indexPath].frame;
Finally, you can choose the appropriate popover (if the app has to work on iPhone) here:
https://www.cocoacontrols.com/search?q=popover
Not perfect, but i think this is efficient!
Yes, SceneKit.
When user perform a touch event, that mean you knew the 2D coordinate on screen, so your only decision is to popover a view or not, even a 3D model is not exist.
First, we can logically split the requirement into two pieces, determine the touching segment, showing right "color" in each segment.
I think the use of 3D model is to determine which piece of data to show in your case if I don't get you wrong. In that case, the SCNView's hit test method will do most of work for you. What you should do is to perform a hit test, take out the hit node and the hit's local 3D coordinate of this node, you can then calculate which segment is hit by this touch and do the decision.
Now how to draw the surface of the cylinder would be the only left question, right? There are various ways to do, for example simply paint each image you need and programmatically and attach it to the cylinder's material or have your image files on disk and use as material for the cylinder ...
I think the problem would be basically solved.
Quick diagrams! I'm trying to implement this:
I have this working almost 100% currently (though this is a slightly different stage of the animation):
Everything looks good minus the fade effects at the end of the stroke. Is that possible using a simple CGPath? I'm animating strokeStart and strokeEnd to get the current effect. I've tried using CAGradientLayer as a mask on the layer, but that adds a gradient over the entire layer, not just the ends. Overriding drawRect isn't possible since I'm doing this dynamically with animations.
Any thoughts about how to achieve this effect? I have no idea which direction to go.
Depending on how important opacity is and how complex the rest of the animation is, one option would be to make two blurred tail objects that follow the ends of the path as it is animating.
Roundabout solution, sorry I can't think of another versatile way!
I'm working on building a custom control. Basically I want to allow the application to generate rectangles (positioned at x = 0 with a variable y value that increases as each rectangle is added).
I'd like them to respond to gestures where they have two positions (closed - which mostly hidden, open - expanded fully so that the entire rectangle is still visible but tethered to the side).
I've already designed an application with this in mind. Seeing as the rectangles will be generated by the users, I assume core graphics would be best for the job. Also, I want the rectangles to display different information based on their gesture-related position.
Is it possible to combine core graphics with these types of controls? I know this is asking a lot.
It's just that I'm having trouble determining how to combine each component in code.
Any advice would be greatly appreciated. Thanks!
Clearly, we're not here to write code for you, but a few thoughts:
You say that you assume Core Graphics would be best for the job. You definitely could, but you could also use CAShapeLayer, too.
So you might create a gesture recognizer whose handler:
Creates a CAShapeLayer when the gesture's state is UIGestureStateBegan and adds it as a sublayer of the view's layer.
Replace that shape layer's path property with the CGPath of a UIBezierPath which is created on the basis of updated location that the gesture recognizer handler captures when the gesture's state is UIGestureStateChanged.
I'd suggest you take a crack at that (googling "CAShapeLayer tutorial" or "UIPanGestureRecognizer example" or what have you, if any of these concepts are unfamiliar).
If you really want to use Core Graphics, you would have a custom UIView subclass whose drawRect draws all of the rectangles. Conceptually it's very similar to the above, but you have to also writing your own rectangle drawing code that you'll put in drawRect, rather than letting CAShapeLayer do that for you.
I'd like to build a random animation of a imageview on iPad. What i manage to build so far is this:
The arrow represents my imageview. it moves to the bounds of its parent view an changes it direction. Actually this is not what i want. Id like to move the view randomly in it's parent view, in curves. And also adjust its heading, like in this figure:
I've no clue how to solve this and in particular how to generate a nice smooth path. Maybe someone has a hint for me.
Brad Larson answers a question that will give you some insight here: How do I translate parabolically?
Choosing random points is pretty easy and when you add them using a keyframe animation and a path, you get the smoothing you're looking for. You would just need to add the points to the path reference.
You add the path to the keyframe animation according to the link above and then add the animation to the UIImagView's layer with:
[[imageView layer] addAnimation:pathAnimation forKey:#"pathAnimation"];
Best regards.
Try out with Bezier curves with following
Drawing bezier curves with my finger in iOS?
and
CGPathReference
You would actually get quite far by just configuring the calculation mode of the key frame animation to be cubic
positionAniamation.calculationMode = kCAAnimationCubic; // or kCAAnimationCubicPaced
That will cause it to construct cubic splines between the points specified in the values array.
I'm struggling with conceptualizing animations with a CALayer as opposed to UIView's own animation methods. Throw "Core Animation" into this and, well, maybe someone can articulate these concepts from a high level so I can better visualize what's happening and why I'd want to migrate UIView animations (which I'm quite familiar with now) to CALayer animations on the iPhone. Every view in Cocoa-Touch automatically gets a layer. And, it seems, you can animate one and/or the other?!? Even mix them together?!? But why? Where's the line? What's the pro/con to each?
The Core Animation Programming Guide immediately jumps into Layer & Timing Classes and I think need to take a step back and understand why these varied pieces exist and how relate to each other.
Use views for control and layers for eye candy. Layers don't receive events so it's easier to use a view for those cases, but when you want to animate a sprite or backgrounds, etc., layers make sense. Events pass right through layers to the backing view so you can have a pretty visual representation without messing up your events. Try to overlay a view that you're just using for visual representation and you'll have to pass tap events through to the underlying view yourself.
An UIView is always rendered to a CALayer. When you use UIView methods to animate a view, you are effectively manipulating the underlying CALayer.
If you need to do simple things, use the UIView methods. For more complex situatins, or if you want layers not associated with any view in particular, use CALayers.
I've done a bunch of apps in the past year. Here's my rule of thumb:
Use UIView until it doesn't do what you want.
Then move to CoreAnimation. But before you get into it too much...
If you write more than a few animations, use Cocos2D.
UIView transforms are only 2D and are restricted to that, LAyer transforms however can be 3D and you should use those if you want to do 3D stuff, UIView animation will work if you change either the UIView transform or the CALayer transform. So at a basic level, you can do a lot more manipulation when you are working with a Layer rather than the View.
I am not sure if I am misunderstanding Chris' response to "What's Cocos2D doing better? Don't you have other problems then, regarding the touch event handling and many other stuff that misses in openGL ES?"
It sounds like the answer suggests Cocos2D is not based on the OpenGL ES framework when in fact it actual is. While it is a great 2D game engine it does implement OpenGL for much of it's rendering - attached to a physics library it allows for a lot of very interesting possibilities for animation - and Chris is correct - it is a lot less coding indeed.