I'm am an experienced flash developer who's been learning objective-c for the last 5 months.
I am beginning the development of an app previously prototyped in Flash and I'm trying to guess what could be the best approach to port it to iOS.
My app is kind of a music game. It consists of some dynamic graphics (circles growing and rotating), with typography also changing and rotating. Everything moves in sync with music. And at the same time the user can interact with the app (moving and rotating things) and some sounds will change depending on his actions.
Graphics can't be bitmaps because they get redrawn every frame.
This was easy to develop with Flash due to its management of vector graphics. But I'm not sure what would be the best way to do it in objective-c.
My options, I guess are things like: Core Graphics, OpenGL, maybe Cocos2D (not sure if that would be to kill a flea with a sledgehammer). Or even things like OpenFrameworks or Cinder, but I rather use objective-c other than c++.
Any hint on where to look at will be appreciated.
EDIT:
I can't really put a real screenshot due to confidentiality issues. But it is something similar to this
But it will be interactive and sections would change size and disappear depending on the music and user interaction.
Which graphics library should you use? The answer is going to depend a lot on what you know or could learn. OpenGL will use hardware acceleration, so it's probably fastest. But OpenGL doesn't have built-in functions for drawing arc segments or any curves or text at all, so you'd probably have to do it yourself. Also, OpenGL is notoriously difficult to learn.
Core Graphics has many cool methods for drawing vector graphics (rectangles, arcs, general paths, etc.), but might be slower than you want, depending on what you're trying to do. Without having code to actually run it's hard to say.
It looks like Cocos2D is built on OpenGL and is made to be simple. I see lots of mention of sprites on their website, but nothing about vector graphics. (I've never used it, so it could be there and I'm just not seeing it.)
If I were in your position, I'd look into cocos2d and see if it does vector graphics at all. If not, I might give Core Graphics a try and see what performance was like. I know OpenGL can do what you want, but it can be difficult to learn, so I'd probably do that last.
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Does soneone of you have a good solution for external rendering for Microsoft HoloLens Apps? Specified: Is it possible to let my laptop render an amount of 3D objects that is too much for the HoloLens GPU and then display them with the HoloLens by wifi including the spatial mapping and interaction?
It's possible to render remotely both directly from the unity editor and from a built application.
While neither achieves your goal of a "good solution" they both allow very intensive applications to at least run at all.
This walks you through how to add it to an app you're building.
https://learn.microsoft.com/en-us/windows/mixed-reality/add-holographic-remoting
This is for running directly from the editor:
https://blogs.unity3d.com/2018/05/30/create-enhanced-3d-visuals-with-holographic-emulation-in-uwp/
I don't think this is possible since, you can't really access the OS or the processor at all on the HoloLens. Even if you do manage to send the data to a 3rd party to process, the data will still need to be run back through the HoloLens which is really just the same as before.
You may find a way to perhaps hook up a VR backpack to it but even then, I highly doubt it would be possible.
If you are having trouble rendering 3D objects, then you should reduce the number of triangles, get a lower resolution shader on it, or reduce the size of the object. The biggest factor in processing 3D objects on the HoloLens is how much space is being drawn on the lens. If your object takes up 25% of the view instead of 100% it will be easier to process on the HoloLens.
Also if you can't avoid a lot of objects in the scene maybe check out LOD, which reduces the resolution of objects based off of distance to it and vice versa.
Suppose I have a 3D (but not stereoscopic) DirectX game or program. Is there a way for a second program (or a driver) to change the camera position in the game?
I'm trying to build a head-tracking plugin or driver that I can use for my DirectX games/programs. An inertial motion sensor will give me the position of my head but my problem is using that position data to change the camera position, not with the hardware/math concerns of head tracking.
I haven't been able to find anything on how to do this so far, but iZ3D was able to create two cameras near the original camera and use it for stereoscopic stuff, so I know there exists some hook/link/connection into DirectX that makes camera manipulation by a second program possible.
If I am able to get this to work I'll release the code.
-Shane
Hooking Direct3D calls in its nature is just hooking DLL calls. I.e. its not something special to D3D but just a generic technique. Try googling for "hook dll" or start from here: [C++] Direct3D hooking sample. As it always happens with hooks there are many caveats and you'll have to make a pretty huge boilerplate to satisfy all needs of the hooked application.
Though, manipulation with camera in games usually gives not good results. There are at least two key features of modern PC game which will severely limit your idea:
Pre-clipping. Almost any game engine filters out objects that are behind the viewing plane. So when you rotate camera to a side you won't see the objects you'd expect to see in a real world - they were just not sent to D3D since game doesn't know that viewing plane has changed.
Multiple passes rendering. Many popular post processing effects are done in extra passes (either thru the whole scene or just part of it). Mirrors and "screens" are the most known such effects. Without knowing what camera you're manipulating with you'll most likely just break the scene.
Btw, #2 is the reason why stereoscopic mode is not 100% compatible with all games. For example, in Source engine HDR scenes are rendered in three passes and if you don't know how to distinguish them you'll do nothing but break the game. Take a look at how nVidia implements their stereoscopic mode: they make a separate hook for every popular game and even with this approach it's not always possible to get expected result.
I have started working on a new Xcode project, a game to be exact. Now, i will be adding what you might call sprites to the screen quite frequently, and the image that represents them will be either of a total of 3. Now, when i start adding these images programmatically to the viewcontrollers view, the app will start lagging as i reach a still fairly low number compared to many other games out there (maybe 5-10). Now, i was wondering if it had to do with caching? i see you can cache images in Cocos2d which i just started learning, to reduce the processing time of rendering the images on-screen. How do i come about this in Xcode?
IN SHORT: How do i "cache" or allow Xcode to rapidly draw images to prevent lag when drawing multiple images?
Thanks on advance.
JBJ
Xcode is the IDE and development environment, it's not the operating system, which is where any caching would really be happening.
UIImage does do some kind of caching (here is a related question that talks about this) but if you're going to be using cocos2d, you should rely more upon whatever your game framework provides versus what the O.S> provides.
You should rely on a proper API (like cocos2d, since you are talking about it) to develop games, not on UIKit classes which are not meant to be used in this way.. why should caching be supported in something that is used for layouts and interfaces and not for realtime rendering?
I agree with Jack that you should probably just use Cocos2D. But if you want to do it yourself, you should use the imageNamed: method of UIImage to load the images, because it takes care of caching automatically, and you should use UIImageView to display the images, because Apple has put a lot of effort into optimizing UIImageView.
New to Mac OS X, familiar with Windows. Windows has DirectShow, a good number of built-in filters, COM programming, and GraphEdit for very fast prototyping and snooping on the graphs you've constructed in code.
I'm now about to go to the Mac to work with cameras, webcams, microphones, color spaces, files, splitting, synchronization, rendering, file reading, file saving, and many of things I've come to take for granted with DirecShow when putting together applications for live performance. On the Mac side, so far I've found ... nothing! Either I don't know where to look or I'm having the toughest time tying the Mac's reputation for its ease of handling media with a coherent programmatic ability to get in there and start messin' with media manipulatin' building blocks.
I've seen some weak suggestions to use gstreamer or some library for QT but I can't bring myself to believe that this is the Apple way to go. And I've come across some QuickTime documentation but I'm not looking to do transitions, sprites, broadcasting, ...
Having a brain trained on DirectShow means I don't even know how Apple thinks about providing DirectShow-like functionality. That means I don't know the right keywords and don't even know where to look. Books? Bought a few. Now I might be able to write some code that can edit your sister's wedding video (if I can't make decent headway on this topic I may next be asking what that'd be worth to you), but for identifying what filters are available and how to string them together ... nothing. Suggestions?
Video handling is going through a huge transition on the Mac at the moment. QuickTime is very old, but also big and powerful, so it's been undergoing an incremental replacement process for the past 5 years or so.
That said, QTKit is the QuickTime subset (capture, playback, format conversion and basic video editing) which is supported going forward. The legacy QuickTime APIs are still there for the moment, and probably will remain at least until its major features are available elsewhere, but are 32-bit only. For some involved video stuff you may end up needing to use it in places.
At the moment, iOS is ahead of the Mac because it could start from scratch with AV Foundation. The future of the Mac media frameworks will probably either be AV Foundation directly (with QTKit being a lightweight shim over the top) or an extension of QTKit that looks very similar.
For audio there's Core Audio which is on Mac and iOS and isn't going away any time soon. It's quite powerful but somewhat obtuse in places. Luckily online support is very good; the mailing list is an essential resource.
For filters and frame-level processing you've got Core Video as someone else mentioned, as well as Core Image. For motion graphics there's Quartz Composer which includes a graphical editor and a plugin architecture to add your own patches. For programmatic procedural animation and easily mixing rendering models (OpenGL, Quartz, video, etc.) there's Core Animation.
In addition to all of these, of course there's no reason you can't use open source libraries where the built-in stuff doesn't do what you want.
To address your comment below:
In QuickTime (and QTKit), individual data types like audio and video are represented as tracks. It may not be immediately clear that QuickTime can open audio as well as video file formats. A common way to combine audio and video would be:
Create a QTMovie with your video file.
Create a QTMovie with your audio file.
Take the QTTrack object representing the audio and add it to the QTMovie with the video in it.
Flatten the movie, so it doesn't simply contain a reference to the other movie but actually contains the audio data.
Write the movie to disk.
Here's an example from Blender. You'll see how the A/V muxing is done in the end_qt function. There's also some use of Core Audio in there (AudioConverter*). (There's some classic QuickTime export code in quicktime_export.c but it doesn't seem to do audio.)
I want to build an app similar to Fat Booth, Aging Boot etc. I am totally noob to digital image processing. where should I start? Some hints?
Processing images on the iPhone with any kind of speed is going to require OpenGL ES. That would be the place to start. (If this is your first iOS project, though, I wouldn’t recommend starting off with GL.)
Apple has an image processing example available here: http://developer.apple.com/iphone/library/samplecode/GLImageProcessing/Introduction/Intro.html.
I imagine the apps you refer to use GL too. Fat Booth, for example, might texture a mesh with your photo, then distort the mesh to make the photo bulge out in the middle. It could also be done purely with fragment shaders.