New user to the site, but I have used it in the past so I felt it best to ask my question here, for the best chance of getting a response.
What I'm dealing with is one object, this being the sprite for my latest app, which I need to check for when it comes in to contact with another object, in this case, a tunnel which will curve.
Now, I'm aware of CGRectIntersectsRect, however I can't see that being helpful, as if I've got 2 UIImages, that being the top and bottom of a "mountain", and said pieces curving, there's no doubt that the sprite would touch the "rectangle".
What I need is something to trigger when the sprite hits the actual wall, however my limited knowledge of Objective-C isn't helping my case.
I imagine someone out there will know what I can do to resolve this, as for all I know it could be a simple solution.
Thank you in advance everyone!
First, I'd probably not build these basic pieces yourself. For iOS 7, you can use SpriteKit, which is built-in. If you want to support older versions of iOS, look at cocos2d (it's good for iOS 7, too).
But to the question, one approach for detecting arbitrary overlaps is to draw both objects into a buffer and check if there are any overlapping pixels (for instance, by drawing one in in pure red, and another in pure green, and then looking for pixels that have both). For a discussion of how to do this kind of thing in Core Graphics, see Clipping a CGRect to a CGPath, which provides sample code for the simplest version (checking for the intersection of a rectangle and curve), but the same approach can be used more generally. Note that this drawing can get expensive if you're doing it constantly, so usually you first check whether the bounding rectangles overlap. That tells you whether it's even worth the trouble to look closer.
But first I'd look at SpriteKit.
Related
I'm making a tile-based adventure game in iOS. Currently my level data is stored in a 100x100 array. I'm considering two approaches for displaying my level data. The easiest approach would be to make an SKSpriteNode for each tile. However, I'm wondering if an iOS device has enough memory for 10,000 nodes. If not I can always create and delete nodes from the level data as needed.
I know this is meant to work with Tiled, but the code in there might help you optimize what you are looking to do. I have done my best to optimize for big maps like the one you are making. The big thing to look at is more so how you are creating textures I know that has been a big killer in the past.
Swift
https://github.com/SpriteKitAlliance/SKATiledMap
Object-C
https://github.com/SpriteKitAlliance/SKAToolKit
Both are designed to load in a JSON string too so there is a chance you could still generate random maps without having to use the Tiled Editor as long as you match the expected format.
Also you may want to consider looking at how culling works in the Objective-C version as we found more recently removing nodes from the parent has really optimized performance on iOS 9.
Hopefully you find some of that helpful and if you have any questions feel free to email me.
Edit
Another option would be to look at Object Pooling. The core concept is to create only sprites you need to display and when you are done store them in a collection of sorts. When you need a new sprite you ask the collection for one and if it doesn't have one you create a new one.
For example you need a grass tile and you ask for one and it doesn't have one that has been already created that is waiting to be used so it creates one. You may do this to fill a 9 x 7 grid to fill up your screen. As you move away grass that gets moved off screen gets tossed into the collection to be used again when the new row comes in and needs grass. This works really well if all you are doing is displaying tiles. Not so great if tiles have dynamic properties that need to be updated and are unique in nature.
Here is a great link even if it is for Unity =)
https://unity3d.com/learn/tutorials/modules/beginner/live-training-archive/object-pooling
I'm working on making a new app in xcode and have run into two problems that always seem to be a problem when I program large projects.
Basically, I want the user of this app to be able to input specifics like size, position, color, and possibly speed and/or direction.
These inputs will create a square of specific size, position, and color which will move around the screen and interact with other squares the user has created.
Now here are my problems:
First: I have absolutely no idea how to create something in code. I know I almost certainly have to do this in a class, but I've never figured out how to do this in a single programming language.
Second: Interaction between the squares. How do I detect collisions between the possibly dozens or hundreds of squares the user creates.
I'd really like to figure out how to do this, especially because I'm sure it'll be helpful in not only this, but many other future projects.
Thanks
I would recommend using sprite kit for the collision detection and creation of the squares. You'll probably want to subclass SKSpriteNode to define the properties for your squares.
https://developer.apple.com/library/ios/documentation/GraphicsAnimation/Conceptual/SpriteKit_PG/Introduction/Introduction.html
I need to add typical finger drawing to an app.
(The usual.... choose colors, erase, thickness - just the usual you see in every app made.)
It's hard to believe I have to program this from scratch, in this day and age?
It's hard to believe there is not a common solution for this?
All I could find is...
https://github.com/levinunnink/Smooth-Line-View
Review: that is a (beautifully written) example fragment of a few lines of code being how to draw with a path, with a good smooth result. It works perfectly, but it's just for drawing one "path." For example, you can't make a drawing with more than one color. there is no undo or anything like that. (See also note on the fourth review item here regarding path-math.)
https://github.com/sumanthk2006/Smooth-Line-View-1 (variation of above, but does not run under ARC, unfortunately demo does not properly launch etc)
Review: this is "abandonedware" or maybe "frustrationware" :) It does not run and is not ARC-ready. It is a seemingly well-written class that claims to do undo, colors, erase, etc. It even has a proper delegate to track your button states. But it doesn't work.
UPDATE Regarding this paackage. As a matter of fact, if you massage it it works well. Suggest (i) throw away the example app files. (ii) using modern Xcode, use the "convert to ARC project" feature on the two main files. There are a coupe little problems like it should use awakeFromNib. If you get it working it actually does everything, really well.
THERE ARE SERIOUS BUGS in SmoothLineView1. just to be clear, it suffers some serious bugs - you'll see there's a "streaking" effect when you draw.
http://www.cdframeworks.com/product/brushengine
Review: This commercial package (under $100) is well made and email support is fast. Unfortunately it does not have undo so it's not suitable for many situations. (Also does not have erase.)
Mentioned below is this popular article:
http://mobile.tutsplus.com/tutorials/iphone/ios-sdk_freehand-drawing/
Review: this is a good article on the actual TECHNOLOGY of drawing curves, on the let's say "path-math". Unfortunately it's no help at all if you need a working, ready to use, drawing package (with the obvious features, undo, erase, colors etc) to use in an iOS app. Thus for example, whatever actual solution you were using, you may, perhaps, want to apply the math concepts in this article.
I appreciate that the basic concepts are very simple, it's easy enough to "start from scratch". But it's just - ridiculous - to have to do from scratch for something so commonplace. Is there a solid package I'm missing?
It's fairly amazing that the four scratchy references above are the only things out there.
Any ideas? What's the best package today (late 2013) for adding drawing to an iOS app? THANKS.
As of 2017, I use https://github.com/acerbetti/ACEDrawingView/.
It can be used through cocoa pods, and provide full functionality over integrating a drawing feature in your app (color, brush, size, eraser, undo/redo/, etc).
http://mobile.tutsplus.com/tutorials/iphone/ios-sdk_freehand-drawing/ has a good, clear tutorial on smooth freehand drawing on the ios. If you just follow the tutorial, you can implement it easily into whatever app you are trying to make. It has stuff about increasing line quality and smoothness, and stroke quality.http://www.raywenderlich.com/18840/ is another tutorial on a simple drawing app, self-contained. You can combine aspects of both to get what you want.
edit: https://developer.apple.com/library/ios/samplecode/GLPaint/Introduction/Intro.html is the GLPaint sample provided by apple, which includes detecting shake. I thought it seemed more official, since it's from apple
to answer your question, there is no package for drawing directly, but there is a UIKit class, UIBezierPath, that lets you draw shapes made of straight lines or some curves.
What I basically need to achieve is a Fruit Ninja - style "slash" effect, where the "slash" trails the user's touch and follows the shape of the user's gesture, and is thinner the longer the distance the user has swiped.
The simplest way to achieve this seemed to be to collect all the points the user passes through in a UIBezierPath, and "stretch" an image through the length of the BezierPath. This would achieve the kind of "trailing" effect I was looking for and also ensure that the line is thinner if the distance travelled is longer.
However I can't seem to find a way to actually implement this. Is this even possible?
Alternatives? Thanks.
P.S: This is for a low-medium priority section of a regular app and not a game, so I would like to avoid having go down to OpenGL and spend a lot of time to achieve this (with completely custom drawing, etc). Something at the SDK level would be preferred, and if that's not possible at all, we'll just figure out a different UI.
Thanks!
For pretty easy-to-use stretching teqhniques of images/views you could look into
https://github.com/hfossli/AGGeometryKit/
I recommend trying to draw using CoreGraphics. See this link
http://www.effectiveui.com/blog/2011/12/02/how-to-build-a-simple-painting-app-for-ios/
Okay. Maybe you can use this.
https://github.com/hfossli/AGDraw
Just something I wrote a while ago. Hit clear and try to draw something (clear will toggle between two types of strokes). You'll see the width of the penstroke will increase with the velocity you use.. I guess that fits your need. If you fix some bugs, please make a pull request. You are free to use the code, but I will add a MIT license later.
Right now I have coded about 80% of my game and the remaining 20% is the actual game part of it. I need to know how I should go upon actually making the game part.
Pretty much it will be somewhat similar to Doodle Jump. There will be gravity, the accelerometer, and a spawn system for platforms. I need to know if I should use UIKit or Cocos2D for this.
I know I can do gravity and use the accelerometer easily using UIKit but I am worried about the platform part. My 'Doodle Jump character' is not a regular square or rectangle so should I just crop it as best I can? The reason I am worried is because say the character falls on a platform, so his body could be a little off since CGRectIntersectsRect does not have pixel collision detection, so do you think it is fine the way it is?
If you need more info or aren't sure what I am trying to do, just let me know. In the end I just need to know if I should use Cocos2D or UIKit.
Please let me know your thoughts.
Thanks!
My answer would be that, while you may be able to develop the game in UIKit, my suspiction is that it will be better in the long run to do it in Cocos2D. Not only will you have tools which are better for doing stuff like collision detection, you can also use a Physics Engine to handle the gravity and things like that. Basically, Cocos2d was made to do exactly the kinds of things you want to do, and UIKit wasn't...it was made for user interfaces.
Still, the collision detection you do will, mostly likely, not need to be down the level of individual pixels. One rectangle might be enough, or perhaps you can use several to get more accuracy. So can you pull it off in UIKit...maybe, but I bet your game will turnout better overall if you use Cocos2d.