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Now, in the last lesson, we've prepared all of our assets, so that we can drag and drop them into our ARKit
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app.
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So you should have a video called Harry Potter in the MP4 format.
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You should have a main image that you're gonna be using to recognize in your newspaper and you should
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have your newspaper printed and ready for use.
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Now, let's go ahead and Create a New Xcode Project and make sure you select Augmented Reality app.
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And I'm just gonna call this MagicPaper and, again, make sure you're using SceneKit, and go ahead and
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click Next.
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Then feel free to save it any way you like, but I'm just going to leave it on my desktop for now.
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So, now that we've got our brand-new ARKit app, first things first, I'm going to delete the ship.scn
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file and the texture.
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So let's just hit backspace and move that to trash.
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Next, we need to add our resources to our project.
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So the video I'm simply going to drag and drop into my main folder, the yellow one here, and make sure
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that when you drag and drop it in that you check this part where it says. "Add to targets," namely that
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the video should be accessible by our app called MagicPaper.
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Make sure that this box is ticked.
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This is really important.
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And it will cause you a lot of headache later on trying to fix this if you didn't tick it.
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Now, if you forgot to do it, just simply delete the aasset and drag it back on and make sure that box is
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checked.
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Now, the next step is to incorporate our images for ARImageRecognition.
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So you did this in the last module,
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so I'm going to leave it to you as a challenge and see if you can incorporate the main image that we're
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going to detect.
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All right.
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So this shouldn't be too hard.
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All we need to do is head into assets.xcassets and we're going to right-click in this white area
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here,
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and we're going to create a new AR Resources group.
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And then, I'm going to rename this AR Resources group to our NewsPaperImages. And this is the area
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where we need to drag in our image which is this one. It's called harrypotter, remember?
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And when we drag it in, it will always complain because it doesn't have a physical dimension.
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Now, the physical dimension depends on the size of the paper that you've printed out the newspaper on.
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So once you've printed out the newspaper, you can use a ruler to measure the size of this image.
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So mine turns out to be about 7.6 centimeters in height.
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So let's put 0.076 and it'll calculate the width automatically.
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And now that warning goes away and we've successfully incorporated the image that we want to detect.
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Now, next we can head into our ViewController and we can start writing some code.
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But before we do that, let's make sure we delete all of this part that relates to that ship.scn which
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we deleted earlier on
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and that's the rocket ship that gets included automatically in all the new ARKit templates.
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Here's another challenge, because I know you've done it before and it's always good to practice, write
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some code to make our image recognizable so that when you run the app you should be able to print something
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into the debug console that says, "The image of Harry Potter inside the Assets.xcassets was recognized."
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So, again, we've done this in the previous module.
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So if you need to refresh yourself by looking at the previous lessons, then go ahead and do that.
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But if you really get stuck, then come back and I'll walk you through the solution. Okay.
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So first things first,
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we are now tracking an image, so we need to change this to ARImageTrackingConfiguration.
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And in between creating the configuration and running the configuration, we need to do a few more things.
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We need to tell it which images to track.
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So we need to create a object called trackedImages.
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And this is going to be equal to ARReferenceImage.referenceImages and inGroup Named, so the
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String that we put in here has to match the name of this folder.
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So we called it NewsPaperImages, and that all the words are capitalized.
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"NewsPaperImages." And the bundle is, of course, the main bundle,
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so the current location of this app. This is, again, if you remember, going to be an optional, because this
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might not exist,
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so it might be nil.
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So we need to either unwrap this or use optional binding to keep ourselves safe. Once we are certain
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that there definitely are tracked images, then we're going to set our configuration to tell it that the
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image as it should be tracking are the ones that we specified above. And finally, we need to say that
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our configuration currently only takes a maximum of 1 images to be tracked simultaneously.
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And now, we can check to make sure that these NewsPaperImages definitely do exist and they can be used
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as reference images for tracking. And we're going to do that inside the "if let,"
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and we're gonna say "Images found," and let's go ahead and hit run.
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But before we do that, let's make sure that we select a team so that we can successfully sideload our
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app. And, remember, sideloading all ARKit apps requires a physical device.
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So down here image is found.
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That means that this "if let" statement was true and it was able to locate this NewsPaperImages group.
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So, now that's done, we can delete that.
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And the next step is we need to write some more code to create a plane to put our ARV content onto
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the main image.
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So, again, we've done this before.
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We just need to generate a white rectangle that shows up on the location of the tracked image.
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So, again, I'm going to encourage you to pause the video and try to complete this as a challenge.
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All right.
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So in order to receive the events from our scene when it detects a new image, we need to add a delegate
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method,
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and we're going to add it down here which are the ARSCNViewDelegate. And the one that we need
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is the same as the one that we used before which is renderer nodeFor anchor.
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So the anchor is the image that it found or recognized and we need to return a node to be displayed
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in our scene.
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So here is where we're going to be writing our code.
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And first and foremost, we're going to create a new node which is a SCNNode, and then we're going to
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check to see if this anchor is actually of the data type of ARImageAnchor, rather than just a generic
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ARAnchor.
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Let's go ahead and do an "if let" statement to check, if let imageAnchor equals the anchor that was
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found as,
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so casting its data type as a ARImageAnchor.
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If that is true, then we can do some stuff using this imageAnchor.
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And after all of that stuff is done, we're going to return on node.
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So up here, we've created our brand SceneKit node, and then we're going to use the imageAnchor which
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recognized the image on the scene to add our plane and our rectangle. And then inside here, we're going
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to add some 3D content to our node.
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And once all of that is done, we're going to return the node and render it onto the scene.
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So, now inside this "if let" statement, we need to create our plane. Let's create a plane that is, of course,
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of type SCNPlane, and we need to give it some dimensions.
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So we're going to use the anchor's physical dimensions.
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So we're going to say that the width is equal to imageAnchor.referenceImage.physicalSize.width.
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And the same thing for the height,
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so imageAnchor.referenceImage.physicalSize.height. Okay.
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So, now we have our plane created and we're going to set its material diffuse.content to a new
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UIColor, and it's just going to be a white square.
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So we're going to say 1.0 for white, completely white, and then the alpha will just put
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0.5 to give it a little bit of transparency.
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And now, that we've created are SCNPlane, let's create a planeNode.
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This is going to be of data type SCNNode and it has a geometry of the plane that we just created.
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And now, remember, that our plane always gets rendered at 90 degrees to the image that was recognized.
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So as we did in the last lesson, we need to change or rather rotate it by tapping into the eulerAngle
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property, and we're going to change its x dimension to minus pi divided by 2. And that just rotates
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at anticlockwise by half pi which is by 90 degrees.
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And so that it's flat and flush with the image that was recognized.
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And now, finally, we're going to tap into this node that we created right at the top.
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We're going to say addChildNode and that is going to be this plane node that we created. And now, we're
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ready to test our app and see if we managed to complete that challenge.
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So as soon as we load up the newspaper, you can see that our white rectangle gets rendered onto the newspaper
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and it's pretty much flush and matching the dimensions of that image.
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And even if I sort of moved around and bend it around it's still able to keep track of the location.
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So pretty neat, right?
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Well done
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if you managed to do this all by yourself.
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Don't worry if you've forgotten how to do it and you have to look back at the previous lessons.
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It's the repetition and the reminders that will really help you to turn this into your own.
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And so that in the future when you need to build this feature into your apps, you'll be reminded of this
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tutorial and of this challenge.
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Now, up till now, we haven't really done anything new that we haven't done in the last module. But in the
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next lesson is where we're going to start incorporating SpriteKits in order to render some video onto
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that plane that we just created based off the dimensions of the image that we detected.
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So all of that and more, I'll see you on the next lesson.