I have an app where users can scale and position images in a number of ways. They can drag an entire layer of images around, scale that layer, drag around individual images inside the layer, and scale those individual images.
For some unrelated functionality, I need to generate the image coordinates that a user is pointing to on a given image (ie (0,0) for the top left & (width,height) for the bottom right), independent of how much it has been moved around and scaled. Is there a built in method for tranforming an absolute mouse position to it's relative position on an image (and vice versa) that takes into account any scaling/panning? I have started building my own methods for this tranformation but before I got too deep I wanted to see if it was already built in somewhere that I'm not seeing.
Konva doesn't have such methods yet. You have to implement them manually.
You can subscribe to this related issue: https://github.com/konvajs/konva/issues/303
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I'm working on an app with AR feature. I want to be able to place a 3D model that I have on a horizontal plane that has been detected. So inside the renderer(didAdd) delegate function, I added a node for my 3D model, and set its position to the center of the plane anchor. However, when I run the app to test it, my model is floating on top of the plane instead of standing directly on top of it. My guess is that there is some translation that needs to be done with the coordinates, but don't know about the details. Can somebody give me some pointers?
I am developing horizontal plane detection application using ARKit. It seems to be working fine. Once floor is detected I am trying to place SCNPlane 2meter Hight and 2meter width horizontally from the centre point(detected floor). It is also working fine when floor is empty. If floor has some objects(obstacles like furniture) then SCNPlane is being placed over the object instead of the floor(under the object). How to detect only Horizontal floor excluding the objects. please guide me. thanks
When you are searching and have found the floor the ARKit will put out a grid, normally people use some kind of grid image to display this, but some don't want to show it. Once the grid has placed you place a SCNPlane, which i assume has an physical body as you say it falls towards the floor / furniture?
You can do this in 3 ways:
You can to stop the worldTrackingConfiguration once the floor has
been found.
You can once the floor has been found, fetch that Y-position and bind every object to fall towards that Y-position.
I guess you could check if the Y-position of the new detection overlaps with the floor detection, then it's fine else it's not. (I have not tested this one)
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'd like to build a menu of 'tiles' using SpriteKit. For simplicity, the tiles are SKSpriteNodes of all the same size, and are housed in a larger 'container' SKSpriteNode. The container node is a mask node, so only a subset of the menu tiles are shown at a given time. Dragging up or down on a tile should scroll the list of tiles up or down, respectively.
Right now, when a drag is detected over a tile, I just reposition all tiles up or down--easy. There are two other constraints on the problem, though. The top tile should never scroll below the top of the mask/container node. And, the bottom tile should never scroll above the bottom of the mask/container node. Taken together, this keeps the list of tiles from ever being completely dragged to a place where they are hidden/unreachable.
This problem seemed like it would be elegantly solved with either SKConstraints or SKPhysicsJoints. I've tried a lot of combinations, but nothing seems to give me the desired effect.
For instance, I've used an SKPhysicsJointFixed to pin each pair of neighboring tiles together. This has two problems--first, the tiles are 'sluggish' when dragged, so the finger drags more quickly than the tile to the point that it is no longer over the tile, and the drag stops being recognized as on the node. Second, this pin allows the tiles to rotate freely about the anchor point. I added an SKConstraint to restrict the z-rotation of every tile, but now the tiles can barely be dragged at all.
I tried implementing everything with just SKConstraints, so I wouldn't have to fuss with setting masses correctly, etc., in order to make the physics approach feel more usable. I added a constraint on the x position of every tile so that they could only be dragged vertically. Then, I added another with SKConstraint.distance(_:toNode:) on every pair of tiles to keep them separated by the correct vertical distance. The problem with this is, given two tiles, if I add this distance constraint on each, only the last tile to be given the constraint is allowed to move. It moves and the other tile follows this tile correctly. That other tile can't be moved at all, though.
Then there comes the problem of keeping at least some part of the set of tiles 'in bounds', so that they never are dragged completely outside of the mask node, and thus not visible/unreachable. A constraint/joint seemed like it might work here--add some constraint/joint to the bottom tile keeping it above the bottom of the mask node, and similarly for the top tile. But now, how do I use a constraint/joint to keep the bottom tile above the bottom of the bottom of the mask node but let it move below this point, and vice versa for the top tile?
Am I going about this all wrong? Is using constraints/joints not the correct approach? Obviously, I can hand code all of these restrictions, but it seems like constraints/joints would solve this problem so much more elegantly, while also letting me rely on the physics world for some springiness, flicking, etc. If there's a good way to do what I'm trying to do, would someone please provide a suggestion?
Many thanks!
I have been searching from last two days on internet, I have checked many source codes on net but none of them has provided the result I want.
The image rotation would have perspective but still there would be no changes in the heights of both left and right sides of an image.
I want to set image inside the laptop screen
Please help me out, Thanks.
So you want to 2D pespective drawing of a laptop screen (on an iOS device?) and put a 2D image on that screen, but with the image transformed so its perspective looks correct on the laptop screen, right?
What you need to do is to add an image view on top of your laptop image view. Lets call it laptopScreenImageView.
Then apply a CATransform3D to that the laptopScreenImageView's layer.
The trick to get 3D perspective out of a CALayer is to modify the .m34 value of the transform. Typically you set the .m34 value to a very small negative number, somewhere around -1/200 to -1/500 (the denominator in the fraction is the z coordinate of the "eye position" for viewing the perspective image, in pixels, or how many pixels "above" the image the viewer's eye should seem to be. I don't fully understand it, to be honest. I fiddle with the .m34 value until I get something that looks right.)
Alternately you could try adding a CATransformLayer to your laptop image view's layer, and then adding a CALayer containing your image as a sublayer of the CATransformLayer. I haven't used CATransformLayers before, but the docs say they are supposed to support layers with 3D perspective, giving you the same effect as modifying the .m34 component of a layer's transform.