Currently, RealityKit doesn't have any method that provides the currently visible entities. In SceneKit we do have a method for that particular functionality—nodesInsideFrustum(pointOfView).
Our internal solution is to create a big fake bounding box in front of the camera. We then check intersections between the "frustum" bounding box and each entity's bounding box. That, of course, is a bit cumbersome and inaccurate. I wonder if someone can come up with a better solution who is willing to share it.
You could combine two ARView methods:
ARView.project(position) to get the 2D point in screen space
ARView.bounds.contains(point) to know if it's visible on screen
But it's not enough, you also have to check if the object is behind you:
Entity.position(relativeTo: cameraAnchor) (with cameraAnchor being an AnchorEntity(.camera)) to have the local position
the sign of localPosition.z shows if it's in front or behind the camera
I'm picturing a graph paper like interface, as you click on any given box within the graph it gets colored in. I'm doing this to draw rough shape outlines.
My question is what is the best approach to do this? Draw the lines for the graph and track where the touches occur and color accordingly? Make some array of buttons? Maybe using spritekit?
I'm not too worried about efficiency as I'm not doing anything too complicated but I'm just trying to find some common design ideas behind it.
Something visually similar to this.
You can accomplish some pretty complex behaviours with a UICollectionView and a custom layout. UICollectionView is nice because it manages taps and drawing each cell individually, which should vastly simplify things for you.
Hi I'm making a baseball app and I want from users to input strike zone on a grid like this:
How can I build the visual part so that I won't have too much trouble with implementation of a tap gesture recogniser. It'll be great if I can make this resizable so it will look great on many different devices.
With the touch gesture I need to handle so kind of recognizing position in two ways.
In which section the touch was detected.
What are the approximate coordinates inside this section.
This data will be saved on a cloud and can be later used to show the dot on this grid on other devices.
Is there a way to detect touch in a non rectangular shapes? Maybe with Bezier Paths.
Do you have a suggestion how ti appear on screen without using whole grid as a image. I'd rather divide it in Outer grid and the Inner grid somehow and than create all the pieces in each of this grids. 8 pieces in outer and 9 in inner grid.
You can start with UIBezierPath and its method containsPoint:, although this method "does not take into account the line width used to stroke the path." (link), it is also true for UIBezierPath.
Refer further to this article.
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.
I am looking into making an iOS app that has little creatures. I plan on having these creatures grow and change shapes based on user interaction. So the creatures could end up looking very different based off what the user does.
My problem is animating these creatures. I have dealt with simple animations in the past with cocos2d, but nothing like this.
How can I animate these creatures being different sizes and shapes without having my graphic designer draw every possible image that could be used. In the game spore a user can create an animal of whatever shape or size they want and these animals animate. My question is how can I do something similar in 2d? I know this can't be a simple answer, but a point in the right direction is all I am looking for.
You could use some CGAffineTransforms to scale your drawing and custom filters with Core Image maybe to change the color.