I want to determinate the intersection's Rect / Polygon of 2 overlapping SkNodes in Sprite-kit.
The method :
SKNode.intersectsNode(<#T##SKNode#>)
returns only true or false if there is an intersection, but i want to know also the intersection's area.
Can somebody help me? (I want to determinate the green triangle)
Googling "area of intersection of two rectangles" shows this has been addressed multiple times on SO, like here, and here.
As far as Sprite Kit specific: you are going to have to implement some logic (to test for intersection, containment, etc...) and math (to calculate the area of the intersection,) AFAIK there is nothing built into SK to do it for you.
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.
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.
I am newbie in IOS Gaming, and i need to create a game using Sprite Kit framework for functionality similar to angry bird pulley system, and also wants to find the distance the object is travelled from the pulley to its landing.
Can anyone help me out with this, i would be thankfull for it.
Thanks in advance.
One way you could code a slingshot effect would to use a starting point on the screen at let's say (x=100,y=100). You would display a SpriteNode of a slingshot with the Y centered at the (100,100).
The next step would be to use touchesBegan:withEvent: in the area of the slingshot to let your code know the player is looking to shoot the slingshot.
You would use touchesMoved:withEvent: to track how far back (how much tension) the player is pulling back from the slingshot.
The release would be triggtouchesEnded:withEvent. Based on how far the touch began (x=100) and how far back is was released (for example x=30), you can apply force like this:
float forceUsed = startTouchX - endTouchX;
[_projectile.physicsBody applyForce:CGVectorMake(forceUsed, 0)];
If you are looking to angle the shot you would also have to track Y and use that variable instead of the 0 above.
As for calculating distance between 2 points on the screen, it boils down to x and y coordinates. Subtract objectA.position.x from objectB.position.x
Things can get a lot more complex of course but that all depends on what you want to do in your code. Hope this helps.
P.S. The touches above are all part of the UIResponder Class.
Below is a screenshot from a famous structure building game.
As you can see rods are attached together with ball joints. I'm trying to achieve something similar with Cosos2d on iPhone. I've got two questions here:
Should I draw those ball joints or should I just add them as sprites?
I guess the rods are not drawn bur are rather images. But considering that the length of the rods will change depending on need, how do I make rods with different lengths from just one image?
I am not sure what would be the best approach for one. I would imagine that either way would be fine, but it would be harder to achieve whatever visual affect you want through drawing them. I think the hardest part would be making sure that they are anchored to vertices in a grid system that has the dimension that you want.
As for (2) you can always scale your image.
CCSprite *rod = [CCSprite spriteWithFile:#"rod.png"];
rod.scaleY = 2.0; //or scaleX
Then rotate and change its anchor points as needed.
Again I imagine the most difficult part would be anchoring them and positioning them correctly, so that align properly with the vertices.
I feel stupid asking this question, but I can not find a clear answer anywhere (or much of an answer at all) so I feel I must ask. Is there anyone out there who can explain clearly how the parallaxRatio of CCParallaxNode works?
I have checked the source of CCParallaxNode and it does not explain it at all. I have searched the internet and stackOverflow extensively. I have tried to do good old trial and error. I'm still confused.
[parallaxLayer addChild:backgroundEffect_subtleRed z:100 parallaxRatio:ccp(0.5, 0.5) positionOffset:backgroundEffect_subtleRed.position];
In this piece of code I am trying to add a particle emitter to a parallaxLayer and have it move somewhat like you would expect an object on a parallax layer to move. Unfortunately I do not see the particles at all. I have had this problem anytime I try to add anything to a parallaxNode when I want it to move. I have been using CCParallaxNode to create static UI layers, but have not been able to use them for what they were built to do.
In summary:
parallaxRatio takes a CGPoint. What do the floats in the CGPoint apply to? Are they ratios of x and y in relation to the window? Are they (parallaxLayerMovementInRelationTo, parentNode)? A working piece of example code would be very helpful.
Thank you.
To quote from a cocos2d book I own:
[paraNode addChild:para1 z:1 parallaxRatio:CGPointMake(0.5f, 0) positionOffset:topOffset];
[paraNode addChild:para2 z:2 parallaxRatio:CGPointMake(1, 0) positionOffset:topOffset];
[paraNode addChild:para3 z:4 parallaxRatio:CGPointMake(2, 0) positionOffset:midOffset];
[paraNode addChild:para4 z:3 parallaxRatio:CGPointMake(3, 0) positionOffset:downOffset];
"The CCParallaxNode is created like any other node, but its children are added using a special initializer. With it you specify the parallax ratio, which is a CGPoint used as a multiplier for any movement of the CCParallaxNode In this case, para1 would move at half the speed, para2 at the normal speed, para3 at double the speed of the CCParallaxNode, and so on"
So basically, its the ratio that the individual layers are moved in the relation to the movement of the whole CCParallaxNode.