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ofxARKit

openFrameworks + ARKit

A Basic toolkit for an IOS app with ARKit support.

This is an openFrameworks addon that provides some helper classes for working within ARKit.

Installation and project setup

First

then

  • Download openFrameworks here
  • clone this repo into your addons folder
  • start a new project with the project generator.

After you've opened up the project file

  • add a permission setting in your ofxIOS-Info.plist file. See Permissions below.
  • set the project target for IOS 11 / 12 / 13 / 14
  • you may need to do two things with the Shader.metal file
    • Add it to the list of compiled sources
    • You will also likely need to make sure to set the file designation back to it's default(for some reason it's marked as "Data" in the projectGenerator generated project)

Note that you may have to repeat these steps if you make any changes to your project via the generator.

Possible Device limitations

Note that with recent versions of ARKit, there are some advanced features that only work on more recent devices like human occlusion. According to Apple People Occlusion and the use of motion capture, simultaneous front and back camera, and multiple face tracking are supported on devices with A12/A12X Bionic chips, ANE, and TrueDepth Camera.

Initializing ARKit

To get started, you need to initialize the ARKit framework. This can be done a couple of different ways. ofxARKit provides a helper api to quickly initialize a session without too much fuss.

SessionSetup

    ofxARKit::core::SessionFormat format;
    format.enablePlaneTracking().enableLighting();
    auto session = ARCore::generateNewSession(format);

The SessionFormat object is a way to enable various features of ARKit in a more straightforward manner. Passing an instance of an SessionFormat object to ARCore::generateNewSession will automatically generate a new ARSession object, while ensuring the specified features are useable on your device.

You can of course, write things by hand which isn't too difficult either.

Raw Objective-C

@interface <your view controller name>()
@property (nonatomic, strong) ARSession *session;
@end


// then somewhere in your implementation block...
// official example shows you ought to declare the session in viewWillLoad and initialize in viewWillAppear but it probably doesn't matter.

self.session = [ARSession new];

// World tracking is used for 6DOF, there are other tracking configurations as well, see
// https://developer.apple.com/documentation/arkit/arconfiguration
ARWorldTrackingConfiguration *configuration = [ARWorldTrackingConfiguration new];

// setup horizontal plane detection - note that this is optional
configuration.planeDetection = ARPlaneDetectionHorizontal;

// start the session
[self.session runWithConfiguration:configuration];

As to where to initialize, it really doesn't matter all that much, if your project setup is more in the form of a traditional IOS objective-c app, you can set things up in your view controller, or if your app is more like a normal oF app, you should be able to just as easily set things up in your setup function.

Potential Hurdles in setup of ARKit

Though ARKit is supported on all devices with an A9 chip(6s onwards I believe) - it is helpful to have a fairly recent device or you may experience near immediate degradation of tracking performance. That being said - ARKit is helpful in that manner by warning you of when you're loosing performance by spitting out a message to the effect of ...tracking performance reduced due to resource constraints...

FPS appears to be minimally affected, but like the message says, things might not work as well.

If you see the message pop up, the ARKit api offers a limited function set to see what the reason might be in the degredation of tracking quality. You can log the current tracking status by

  • calling logTrackingState in ARCam. Will log to the console a basic string describing the status.
  • you can also call getTrackingState in either class to get the raw tracking state from ARKit.
  • ARProcessor provides a debugInfo object which is an instance of ARDebugInfo which can be used as well. Using this will also provide information about FPS, etc.

Note that in order for those functions to work, you'll need to call the setup function of either of ARCam or ARProcessor and pass in the boolean true

Permissions

For ARKit and iOS in general,a there are several permissions you may need to request from the user depending on the kinds of features you're looking to utilize. At a minimum you'll have to enable the Privacy - Camera Usage Description in your ofxiOS-Info.plist file. The value for this field is just the string you want to show users when you ask for camera permissions. If you've never touched a plist file before, no worries! Its very easy to change.

For example in the screenshot below screen shot 2017-09-02 at 2 12 39 pm

You'll see I added it to the very end. If the permission isn't there, all you need to do is over over one of the items already in the list and click on the plus sign. This will add a new field and you can just start typing Privacy - Camera Usage Description. Xcode will attempt to autocomplete as well.
If you are trying to use the AirPod Motion with it, you must add an other field : NSMotionUsageDescription.

Deploying to the App Store

By default #AR_FACE_TRACKING is turned on, allowing you to try out examples such as example-face-tracking (if you have an iPhone X). We keep this variable on by default in order to make the plugin easy to experiment with, but if you're not using the TrueDepth API for face tracking in your app then you'll get issues trying to publish to th Apple App Store:

"We noticed your app contains the TrueDepth APIs but we were unable to locate these features in your app. Please provide information about how your app uses the TrueDepth APIs."

To avoid this if you're not using TrueDepth & going to publish to the App Store change the macro defined in ARFaceTrackingBool.h in your OpenFrameworks plugins directory to false:

// Line 2 of ARFaceTrackingBool.h
-  #define AR_FACE_TRACKING true
+  #define AR_FACE_TRACKING false

This will remove the code from compilation so you don't get flagged by Apple for including code you're not using.

Contributing

For me, time is unfortunately a luxury as creative coding is sadly not my day job; I can only hunt and peck at small things here and there. All that as well as a general lack of knowledge on topics required to work effectively with AR all contribute to making it difficult to keep this up to date as I ought to; sooo, if there's something you feel you can contribute, by all means, feel free to make PR's!

As long as it doesn't break anything I'll most likely accept it.

First and formost, please work from the develop branch. This is usually the most up-to-date branch and is intended to be a staging ground for any new features or changes. Once you are done with the feature you would like to add, please make all PRs against the develop branch

A big thank you to all contributors thus far!