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 learning Spritekit right now and I want to detect a collision between two images.
Just a fun picture as an example :
The image is still a rectangle. How can I fit it that this rectangle will fit to the original face? I don't want the collision early when it hits the rectangle of the Image, I want it to collide when it actually hits the black lines of the face.
I hope you can understand my problem.
Thanks for any help.
EDIT:
There are two issues here:
You probably want to set up your SKPhysicsBody to be a path around your SKSpriteNode. For example, something like the following is close:
UIBezierPath *path = [UIBezierPath bezierPathWithOvalInRect:CGRectMake(-40, -22, 80, 39)];
node.physicsBody = [SKPhysicsBody bodyWithPolygonFromPath:path.CGPath];
That's probably not quite right, so feel free to tweak those values, but hopefully it illustrates the idea: Come up with a path that defines your boundary, and then set the physicsBody accordingly.
If you want to see the physics outlines, set showsPhysics on the SKView.
You probably want to mask your image so that the corners of the image are transparent (i.e. have an alpha of zero):
So, when that's on a colored background it looks like:
By masking the corners, you don't have to worry about the white corner covering up something else on the scene.
If its an image thats got white borders all around it, u can edit it in Preview and use Alpha to get rid of all of the white around it.
I think in that case, the sprite's collision method will collide with the black lines.
Although I am quite experienced with most frameworks in iOS, I have no clue when it comes to 3D modelling. I even worked with SpriteKit, but never with something like SceneKit.
Now a customer wants a very ambitious menu involving a 3D object, an 'icosahedron' to be exact. I want it to look something like this:
So I just want to draw the lines, and grey out the 'see-through' lines on the back. Eventually I want the user to be able to freely rotate the object in 3D.
I already found this question with an example project attached, but this just draws a simple cube: Stroke Width with a SceneKit line primitive type
I have no clue how to approach a more complex shape.
Any help in the right direction would be appreciated! I don't even need to use SceneKit, but it seemed like the best approach to me. Any other suggestions are welcome.
to build an icosahedron you can use SCNSphere and set its geodesic property to YES.
Using shader modifiers to draw the wireframe (as described in Stroke Width with a SceneKit line primitive type) is a good idea.
But in your case lines are not always plain or dotted — it depends on the orientation of the icosahedron. To solve that you can rely on gl_FrontFacing to determine whether the edge belongs to a front-facing or back-facing triangle.
so I'm making a game and pretty much when the player (which is a triangular shaped rocket) hits an object flying at you (a rock) the game ends. I have everything working well but my problem is the rocket is a triangle yet the image view its in is a rectangle. So if the edge of the image view touches the rock the game will end even though the actual rocket didn't touch the object. So basically how can I make the rock image view not recognize the parts of the rocket image view which are empty? Basically a triangular shaped image view.
Thank you for your help. Let me know if you need more info or want to see the code I have for them to collide.
You analytically present the triangle with 3 points and a rock with a center and radius then find and implement an algorithm checking a hit test between those 2 shapes. Or draw the two shapes onto some graphics context using an appropriate blending and check for overlapping pixels (for instance draw one as red and another as green and look if a pixel that is both red and green exists) you could actually do that with 2 image views having those colors and .5f alpha added on the 3rd invisible view but you would need to get the image from the view and then iterate through all the pixels. In any of the cases do this check only after the corresponding view frames overlap.
I am drawing, or should I say "stamping", an image using the CGContextDrawImage method in Objective C. The image gets drawn to points that are determined by touch movements. Basically I'm stamping an image to create a "brush" effect. Looks something like this:
I am happy with the results, however when the touch moment slows down the image gets drawn on top of its self and ruins the alpha value I want. Is there a blend technique in which the opacity of the image would not stack on top of each other? Or should I just look at changing my points such that they are not so close together when the movement slows down?
Thanks in advance.