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GameKit Configuration File - Apple Documentation out of Date
This is the first time I have tried adding achievements to my games. The online documentation says: "Before you can access achievements in your code, you can configure them in Xcode and sync the configuration updates you make with App Store Connect. Begin configuring achievements by creating a GameKit configuration file. In Xcode, choose File > New > File from Template. Select GameKit File, and click Next. In the sheet that appears, enter a name for the configuration and click Create." Sounds easy - except Xcode 16.2 does not have a GameKit File as one of the Templates. Please advise on how to proceed and it would be nice if the documentation were updated.
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120
May ’25
Can you delete a MTLLibrary once shaders are placed into pipeline?
Hello, I am quite new to using the metal API and was wondering if it was common (or even possible) if you knew that, when a pipeline was created, you never needed to make another one with the same shaders again, if it is safe to release the library the was used to reference the shaders? Only asking because this is possible in other apis, but apple never mentions (as far as I have found) if this is safe or not safe to do.
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374
Oct ’25
How to verify with the appropriate signing authority that Apple signed the public key
Hello I trying to implement authentication via apple services in unity game with server made as another unity app On client side I succesfully got teamPlayerID signature salt timestamp publicKeyUrl According to this documentation https://developer.apple.com/documentation/gamekit/gklocalplayer/fetchitems(foridentityverificationsignature:)?language=objc I have to Verify with the appropriate signing authority that Apple signed the public key. As I said my server is special build of unity project So now I have this kind of C# programm to check apple authority over public certificate i got from publicKeyUrl TextAsset textAsset; byte[] bytes; textAsset = Resources.Load<TextAsset>("AppleRootCA-G3"); bytes = textAsset.bytes; rootCert.ChainPolicy.ExtraStore.Add(new X509Certificate2(bytes)); textAsset = Resources.Load<TextAsset>("AppleRootCA-G2"); bytes = textAsset.bytes; rootCert.ChainPolicy.ExtraStore.Add(new X509Certificate2(bytes)); textAsset = Resources.Load<TextAsset>("AppleIncRootCertificate"); bytes = textAsset.bytes; rootCert.ChainPolicy.ExtraStore.Add(new X509Certificate2(bytes)); rootCert.Build(cert); Where cert is X509Certificate2 object I ge from publicKeyUrl AppleIncRootCertificate AppleRootCA-G2 AppleRootCA-G3 is certificates I got from https://www.apple.com/certificateauthority/ But it is not work Anytime rootCert.Build(cert); return false Why it is not work? May be I build keychain using wrong root CA cert? Or whole approach incorrect? Please help
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116
Jun ’25
Metal fails to create PSO on AMD based GPUs
Hello, Shaders in our application is written using HLSL and we rely on Metal Shader Converter to convert DXIL to Metal IR. We ran into an issue that causes metal pipeline state creation to fail when vertex stage-in function is used on AMD GPUs. Here's the error reported by Metal in Xcode output: Compiler failed with XPC_ERROR_CONNECTION_INTERRUPTED XPC_ERROR_CONNECTION_INTERRUPTED MTLCompiler: Compilation failed with XPC_ERROR_CONNECTION_INTERRUPTED on 4 try. This error suggests an unexpected interruption in the connection. Possible reasons: a crash in the compiler service, termination by the OS due to resource constraints (e.g., jetsam), a timeout in the service, or an issue with IPC. Verify system stability and check the logs for more details. Compiler failed with XPC_ERROR_CONNECTION_INVALID XPC_ERROR_CONNECTION_INVALID MTLCompiler: Compiler encountered XPC_ERROR_CONNECTION_INVALID: failed to check-in, peer may have been unloaded: mach_error=10000003 (is the OS shutting down or process jetsammed?) Compilation failed due to an interrupted connection: XPC_ERROR_CONNECTION_INTERRUPTED. This error occurred after multiple retries. which seems to indicate a internal compiler error. I have a minimal repro here: https://github.com/kcloudy0717/metal_pso_fail/tree/main, simply follow the instructions in README.
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130
Sep ’25
GKLeaderboard.LoadLeaderboards() return empty when testing on Xcode with local gamekit file (Unity)
var allLeaderboards = await GKLeaderboard.LoadLeaderboards(); Log(allLeaderboards.Count); // returns 0 What am I missing?? What doesn’t work: await GKGameActivityDefinition.LoadGameActivityDefinitions() → count = 0 await GKLeaderboard.LoadLeaderboards() (no args) → 0 leaderboards await GKLeaderboard.LoadLeaderboards("MY ID") → returns 0 GkGameActivity.SetScoreOnLeaderboard(Leaderboard, score, context); returns an error since my Leaderboard is null. Activities and leaderboards are defined in GameCenterResources.gamekit in Xcode. Achievements that I add locally in the .gamekit file do not appear at runtime either; only ASC live ones show. ** What works:** xcode- debug- Gamekit- Manage Game progress- I can submit new scores with the plus button and see the notification on my device. await GKLocalPlayer.Authenticate() succeeds. await GKAchievement.LoadAchievements() returns the list of achievements configured in App Store Connect- but not any new local achievements created in Xcode in GameCenterResources.gamekit Environment Device/OS: iPhone on iOS 26.0 beta (Game Center sandbox) Xcode: 26.0 beta 6 Unity: 2022.3.21 Apple GameKit Unity plugin: 2025-beta1 (GameKit package) Signing: Game Center capability enabled; using development provisioning profile GameKit resources: GameCenterResources.gamekit in project (Target: Unity-iPhone), appears under Build Phases → Copy Bundle Resources
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723
Sep ’25
Subject: Handling Z-Up Blender USDZ Models in RealityKit (visionOS) for Transform Updates
Hello everyone, I'm working on a visionOS application using RealityKit and am encountering a common coordinate system challenge when integrating 3D models created in Blender. My goal is to display and dynamically update the Transform (position, rotation, scale) of models created in Blender within RealityKit. The issue arises because Blender's default coordinate system is Z-up, and while exporting to USD/USDZ, I don't have a reliable "Y-up" export option that correctly reorients the model and its transform data for RealityKit's Y-up convention. This means I'm essentially exporting models with their "up" direction along the Z-axis. When I load these Z-up exported models into RealityKit, they are often oriented incorrectly. To then programmatically update their Transform (e.g., move them, rotate them based on game logic, or apply physics), I need to ensure that the Transform values I set align with RealityKit's Y-up system, even though the original model data was authored in a Z-up context. My questions are: What is the recommended transformation process (e.g., using simd_quatf or simd_float4x4) to convert a Transform that was conceptually defined in a Z-up coordinate system to RealityKit's Y-up coordinate system? Specifically, when I have a Transform (or its translation, rotation, scale components) from a Z-up context, how should I apply this to a RealityKit Entity so it appears and behaves correctly in a Y-up world? Are there any existing convenience APIs or helper functions within RealityKit, simd, or other Apple frameworks that simplify this Z-up to Y-up Transform conversion process? Or is a manual application of a transformation quaternion (e.g., simd_quatf(angle: -.pi / 2, axis: [1, 0, 0])) the standard approach? Any guidance, code examples, or best practices from those who have faced similar challenges would be greatly appreciated! Thank you.
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360
Jul ’25
How can I simultaneously apply the drag gesture to multiple entities?
I wanted to drag EntityA while also dragging EntityB independently. I've tried to separate them by entity but it only recognizes the latest drag gesture RealityView { content, attachments in ... } .gesture( DragGesture() .targetedToEntity(EntityA) .onChanged { value in ... } ) .gesture( DragGesture() .targetedToEntity(EntityB) .onChanged { value in ... } ) also tried using the simultaneously but didn't work too, maybe i'm missing something .gesture( DragGesture() .targetedToEntity(EntityA) .onChanged { value in ... } .simultaneously(with: DragGesture() .targetedToEntity(EntityB) .onChanged { value in ... } )
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678
Mar ’25
Testing Gamecenter Accounts
HI all, I'm in the early stages of testing a game that will have real-time device-to-device communication using GameCenter. I've read something about setting up GameCenter "sandbox" accounts to test prior to the game's release, but I can't find anything reliable about how to do so. I've found lots of web pages which purport to describe how to do this task, but what they describe seems to be outdated, as the steps don't appear to be available in modern versions of iOS. I'm testing on iOS 18 and 26. Document search isn't helping--I mostly find information on how to set up StoreKit sandbox accounts, which I assume are different things altogether--so if you could point me towards an article that allows me to test a new, unreleased GameKit app between devices, I'd appreciate it. People are developing GameCenter apps, so I know it's possible... advTHANKSance
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365
Sep ’25
RealityKit and Reality Composer Pro aren't forward or backward compatible with each other
TL;DR: RealityKit and Reality Composer Pro aren't forward or backward compatible with each other, and the resulting error message is terse and unhelpful. (FB14828873) So far, I've been sticking with Xcode 16.4 for development and only using Xcode 26.0 beta experimentally. Yesterday, I used xcode-select to switch to Xcode 26.0 beta 3 to test it, but I forgot to switch back. Consequently, this morning I unintentionally used the future Reality Composer Pro (the version included with Xcode 26) to make a small change to a USD file. Now I realize that if I'm unlucky, it's possible Reality Composer Pro may have silently introduced a small change into the USD file that may make RealityKit fail to read the file on iOS 18 and visionOS 2, which in the past has resulted in hours of debugging to track down the source of the failure, often a single line in the USD file that RealityKit can't communicate to me other than with the error "the operation couldn't be completed". As an analogy, this situation is as if, during regular development (not involving Reality Composer Pro), Xcode didn't warn you about specific API version conflicts, but instead failed with a generic error message, without highlighting the line in your Swift file that was the source of the error.
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439
Jul ’25
Can you reduce drawcalls with FlattenedClone() and PNGs with transparency?
Hello, I want to use flattenedClone() node for the trees in my landscape and reduce the draw call. If my texture uses a jpg file the result is good. If I use a PNG with transparency there is no draw call reduction. Can I use PNGs with transparency with the flattenedClone() ? Below is the structure I'm using: for child in scene_temp.rootNode.childNodes { let newtree = tree.clone() sum_tree.addChildNode(newtree) } let sum_tree_flat = sum_tree.flattenedClone() scene.rootNode.addChildNode(sum_tree_flat) If the tree texture contains a JPG file (diffuse) I get a draw call reduction (< 200 for my complete map) as expected (but no transparency with my leaves). If I use a PNG file, my draw calls are not reduced (> 2000) but I do have my trees with my leaves in transparency. I've tried replacing tree.clone() with tree.flattenedClone() with no results. Thanks for your help. Translated with DeepL.com (free version)
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696
Dec ’24
Game Center achievements global players percent is 0%.
Hello, I’m the developer of the “stepsquad” app. Our app uses the Game Center achievement feature, but we’ve been encountering a problem: the “Global Players” always shows 0%, even though there are friends who have already achieved these achievements. Initially, I thought it might be because the app was newly launched. However, it’s now been over two months since release, and it’s still showing 0%. If anyone has any insight into this issue, please leave a comment.
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570
Jan ’25
RealityKit - How to change camera target in response of a touch event?
Hello, I’m porting my UIKit/SceneKit app to SwiftUI/RealityKit and I’m wondering how to change the camera target programmatically. I created a simple scene in Reality Composer Pro with two spheres. My goal is straightforward: when the user taps a sphere, the camera should look at it as the main target. Following Apple’s videos, I implemented the .gesture modifier and it is printing the tapped sphere correctly, but updating my targetEntity state doesn’t change anything, so the camera won't update its target. Is there a way to access the scene content at that level? Or what else should I do? Here’s my current code implementation: Thanks!
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226
Sep ’25
BillboardComponent causing Model Entity tap recognition issues on iOS 18
Hi, When I attach BillboardComponent to anchor entities, I am no longer able to retrieve the tapped entity anymore because the collision shapes of the entity are messed up due to always orienting it towards the camera. And it does not updated the collision shapes because if I try pressing everywhere that is not my model entity, I get a hit out of nowhere. I tried updating the collision shapes of the entity every frame: for child in existingPassport.mainEntity!.children { child.generateCollisionShapes(recursive: true) } However, nothing comes of it, and it is not a smart solution in the first places because it is too heavy to recreate the shapes every frame. I am using the usual AR View Controller that works when I comment out the BillboardComponent line just fine: private func setupTapRecognizer() { let tapRecognizer = UITapGestureRecognizer(target: self, action: #selector(handleTap)) arView.addGestureRecognizer(tapRecognizer) } @objc func handleTap(_ recognizer: UITapGestureRecognizer) { print("handle tap URL 1") let location = recognizer.location(in: arView) if let entity = arView.entity(at: location) { print("handle tap URL 2") // Assuming each entity has a URL stored in a component if let urlComponent = entity.components[URLComponent.self] { webViewPresenter?.presentFullScreenWebView(url: urlComponent.url) print("handle tap URL: \(urlComponent.url)") } } } How should we tackle this issue on iOS 18? Thanks!
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703
Dec ’24
How to add and remove child entities to a rigged entity in RealityKit?
I am currently using RealityKit (perspective camera) to render a character in my swiftUI app. The character has customization such as clothing items and hair and all objects are properly weighted to the rig. The way the model is setup in Blender is like so: Groups of objects that will be swapped (ex: Shoes -> Shoes objects) and an armature. I then export it to usdc with all objects active. This is the resulting hierarchy: Before exporting for the animation (armature modifier applied), I simply had to store the Model entities and swap them in but now when I export with the Armature Modifier applied, so that animations get exported, the ModelComponent gets flattened to the armature and swapping entities and applying new materials to them is no longer as simple. Here's a demo blend file and usdc export with a setup like mine, having an animated bone to swing a cube and sphere, to be swapped so that only one is visible https://www.dropbox.com/scl/fo/be2q6qcztc83z7c4gj1w0/AMapxWc_ip2KZ8oTOYDUMv8?rlkey=rcdaggcxq06dyen09mw5mqmem&st=bnc0d7j0&dl=0 This is how I'm loading the entity and removing a part, with the demo files import SwiftUI import RealityKit struct SwapDemoView: View { var body: some View { RealityView { content in let camera = PerspectiveCamera() camera.transform.translation = SIMD3(x: 0, y: 0.1, z: 3) guard let root = try? await Entity(named: "simpleSwapDemo") else { fatalError("simpleSwapDemo.usdc is not present") } print(root) // Get initial hierarchy guard let cube = root.findEntity(named: "Cube") else { fatalError("Entity cube doesn't exist") } cube.removeFromParent() // <-- Cube is still visible after removal print(root) // Get hierarchy to confirm removal of cube let resource = root.availableAnimations[0] root.playAnimation(resource.repeat()) content.add(root) content.add(camera) } .background(.white) } } And this is what the entity hierarchy looks like in RealityKit before cube removal ▿ 'root' : Entity, children: 1 ⟐ SynchronizationComponent ⟐ AnimationLibraryComponent ⟐ Transform ▿ 'Armature' : ModelEntity, children: 2 ⟐ SynchronizationComponent ⟐ ModelComponent ⟐ SkeletalPosesComponent ⟐ AnimationLibraryComponent ⟐ Transform ▿ 'Armature' : Entity ⟐ SynchronizationComponent ⟐ Transform ▿ 'Primitives' : Entity, children: 2 ⟐ SynchronizationComponent ⟐ Transform ▿ 'Sphere' : Entity, children: 1 ⟐ SynchronizationComponent ⟐ Transform ▿ 'Sphere' : Entity ⟐ SynchronizationComponent ⟐ Transform ▿ 'Cube' : Entity, children: 1 ⟐ SynchronizationComponent ⟐ Transform ▿ 'Cube' : Entity ⟐ SynchronizationComponent ⟐ Transform And here's the hierarchy after removal ▿ 'root' : Entity, children: 1 ⟐ SynchronizationComponent ⟐ AnimationLibraryComponent ⟐ Transform ▿ 'Armature' : ModelEntity, children: 2 ⟐ SynchronizationComponent ⟐ ModelComponent ⟐ SkeletalPosesComponent ⟐ AnimationLibraryComponent ⟐ Transform ▿ 'Armature' : Entity ⟐ SynchronizationComponent ⟐ Transform ▿ 'Primitives' : Entity, children: 1 ⟐ SynchronizationComponent ⟐ Transform ▿ 'Sphere' : Entity, children: 1 ⟐ SynchronizationComponent ⟐ Transform ▿ 'Sphere' : Entity ⟐ SynchronizationComponent ⟐ Transform And this is the result: What's the best practice here? Should animation be exported separately and then applied to the skeleton? If so, how is that achieved? I'm not really sure how to proceed here.
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131
May ’25
How to implement c for vision ?
I want to use reality to create a custom material that can use my own shader and support Mesh instancing (for rendering 3D Gaussian splating), but I found that CustomMaterial does not support VisionOS. Is there any other interface that can achieve my needs? Where can I find examples?
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81
Jul ’25
How to convert `DragGesture().onEnded`'s velocity CGSize to the SIMD3<Float> required in `PhysicsMotionComponent(linearVelocity, angularVelocity)`?
So if I drag an entity in RealityView I have to disable the PhysicsBodyComponent to make sure nothing fights dragging the entity around. This makes sense. When I finish a drag, this closure gets executed: .gesture( DragGesture() .targetedToAnyEntity() .onChanged { e in // ... } .onEnded { e in let velocity: CGSize = e.gestureValue.velocity } If I now re-add PhysicsBodyComponent to the component I just dragged, and I make it mode: .dynamic it will loose all velocity and drop straight down through gravity. Instead the solution is to apply mode: .kinematic and also apply a PhysicsMotionComponent component to the entity. This should retain velocity after letting go of the object. However, I need to instatiate it with PhysicsMotionComponent(linearVelocity: SIMD3<Float>, angularVelocity: SIMD3<Float>). How can I calculate the linearVelocity and angularVelocity when the e.gestureValue.velocity I get is just a CGSize? Is there another prop of gestureValue I should be looking at?
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824
Jan ’25
RealityView session not terminating when leaving view on iOS
Everything works fine, except when tapping the navigation Back link and returning to the previous view, the AR session inside RealityView does not terminate. The green dot camera indicator stays on, it is still scanning the environment, and if the package has audio in it, the audio will still play, albeit extremely panned on the right channel. I have no issues terminating QuickLook or ARSCNView. I have a simple NavigationLink opening the RealityView... NavigationLink(destination: MyRealityView()) { Text("Open AR") } struct MyRealityView : View { var body: some View { RealityView { content in // Create horizontal plane anchor for the content let anchor = AnchorEntity(.plane(.horizontal, classification: .floor, minimumBounds: [0.5,0.5])) let scene = await loadEntity(named: "Scene") // Add model to anchor anchor.addChild(scene!) content.add(anchor) // View Settings content.camera = .spatialTracking } placeholder: { ProgressView() } .onDisappear { //print("RealityView is disappearing. Cleanup actions here.") } .edgesIgnoringSafeArea(.all) // Activate onTap from Reality Composer Pro .gesture(TapGesture().targetedToAnyEntity().onEnded { value in _ = value.entity.applyTapForBehaviors() }) }} I have experimented with several ways of trying to close it, and I can't figure it out. I have tried State variables and custom Back buttons. I was also trying to working with pause(), but I can't seem to get that to function either. Anyone else have this issue or know of a solution? What am I missing?
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554
Jan ’25