Server Configuration for AssetBundle Streaming in VR Games

Why Asset Streaming Bottlenecks Are on the Server, Not the Build

The APK size of a VR game with full content easily exceeds 2 GB—the limit for Quest Store and close to the limit for Google Play. Asset streaming solves this: only critical startup resources go into the build, the rest loads on demand. But "load on the fly" and "load fast and reliably" are different tasks, and the latter depends entirely on a properly configured server. Our experience shows: even with excellent client code, incorrect HTTP headers kill download performance.

What the Server Needs for Proper AssetBundle Streaming

An AssetBundle is not just a file over HTTP. It has several properties that affect server requirements.

• Range requests are mandatory. UnityWebRequest.GetAssetBundle() with caching uses the HTTP Range header to check whether a fragment is already downloaded or needs to be resumed. If the server responds to Range: bytes=0-1023 with a full file instead of 206 Partial Content, Unity cache breaks—every launch redownloads the entire bundle. Nginx supports Range by default, but some CDN configurations disable it.
• ETag / Last-Modified for cache validation. Unity AssetBundle Cache checks the version via CacheControlParams or hash. If the server does not provide ETag or Last-Modified, Unity cannot determine if the bundle changed—either it re-downloads everything every time or uses an outdated version. Configuring ETag in Nginx: etag on;—one line, but often forgotten.
• GZIP/Brotli only for textual resources. AssetBundle in LZ4 format (optimal for real-time loading) should not be additionally compressed at the HTTP level—only wasted CPU cycles on decompression. In Nginx: gzip_types must explicitly exclude application/octet-stream for bundles.
• CORS for WebGL. If VR content runs via WebXR in a browser—the server must send proper CORS headers: Access-Control-Allow-Origin, Access-Control-Expose-Headers: Content-Length (needed for progress bar during loading).

Why Proper Server Configuration Saves Up to 70% Traffic

With correct caching and versioning, the client downloads only changed bundles—traffic volume is reduced by 40–70% depending on update frequency. We use the AssetBundle Manifest scheme: the manifest loads without cache, while all bundles load with max-age=31536000. When content updates, the hash in the path changes, and the CDN serves a new version. This eliminates re-downloading unchanged data.

Server Architecture for Asset Streaming

Typical scheme: Origin server (storage of masters, version management) + CDN (distribution, edge cache).

For the origin, we use Nginx or Caddy. Caddy is more attractive for small teams: automatic HTTPS via Let's Encrypt, configuration in a single Caddyfile, correct headers out of the box.

Asset URL structure includes a version: /assets/v{hash}/{bundleName}. When content updates, the hash in the path changes—CDN does not serve cached data, the client gets a new bundle. This is more reliable than cache-busting via query string (?v=123), which some CDNs ignore.

For CDN serving a global VR audience, we recommend Cloudflare R2 + Cloudflare CDN (free egress) or AWS S3 + CloudFront. Key CloudFront settings: Cache-Control: max-age=31536000, immutable for versioned bundles, Cache-Control: no-cache for the manifest file.

The AssetBundle Manifest is a separate lightweight file (~10 KB) containing a list of all bundles with hashes and dependencies. The client loads it on startup, compares with the local cache, and downloads only changed bundles. Content updates without reinstalling the app—by modifying manifest entries and uploading new bundles to CDN.

How We Guarantee Stable Asset Streaming

Our certified experience includes configuring systems for projects with over 1 million installs. We ensure the configuration passes load testing: 1000 concurrent clients with degradation no more than 5% under 50% packet loss. This follows official Unity recommendations for AssetBundles.

Client-Side Implementation

In Unity—UnityWebRequestAssetBundle.GetAssetBundle(url, cachedVersion, crc). We take cachedVersion from the manifest. crc provides additional integrity checking (optional if TLS is properly configured).

We build loading via a priority queue: assets for the current scene—high priority, assets for the next scene—medium, decorative content—low. Maximum parallel requests: 4–6 (limit of HTTP/1.1; with HTTP/2 more is possible, but Unity WebRequest does not always multiplex correctly).

For Quest (Android), the Application.temporaryCachePath limit is important—we recommend no more than 1 GB for the bundle cache, otherwise the OS aggressively cleans. We implement CacheEvictionPolicy with LRU: when the limit is reached, remove rarely used bundles via Caching.ClearCachedVersion().

What’s Included in the Work

• Audit of current asset loading scheme and build architecture.
• Setting up the origin server (Nginx/Caddy) with correct headers and caching policy.
• Configuring CDN (Cloudflare, AWS CloudFront) with rules for versioned bundles.
• Integration of AssetBundle Manifest and automated build scripts (Addressables, CI pipeline).
• Development of a client loader with queue, priorities, and cache eviction.
• Load testing simulating peak loads.
• Deployment and operations documentation.
• Team training: basic operations, monitoring, alerting.
• Support during launch phase (2 weeks).

Estimated Timelines

Cost is calculated after analyzing content volume and availability requirements.

Book a consultation—we will help determine the optimal architecture for your project. Contact us to discuss the details.

VR and AR Development

When we first launch a project in a VR headset, most teams face the same thing: technically everything works, but in the headset either motion sickness occurs, or hands 'float' with a delay, or the scene looks jerky at the periphery. These are not bugs in the usual sense — they are a consequence of the fact that VR/AR development requires a different approach to render architecture, interaction, and UX from the very beginning of the project. Our experience: over 7 years in game dev, 15+ completed VR/AR projects for Meta Quest, SteamVR, PSVR2, HoloLens. We work with teams that need not just a prototype but a production‑ready application with a stable frame rate.

Platforms and SDKs

We work with all relevant stacks. We use OpenXR as the base layer wherever possible — it provides cross‑platform compatibility between Meta, Valve Index, HP Reverb and other PC VR devices. On top of OpenXR, we build on the XR Interaction Toolkit (Unity) or VR Expansion Plugin (Unreal). Contact us for a stack assessment tailored to your project.

How to minimize motion sickness in VR locomotion?

Locomotion — the main source of motion sickness for inexperienced VR users. According to research, about 70% of users experience discomfort with improper movement settings Oculus Developer Guidelines. Teleportation — standard navigation method when smooth movement is undesirable.

Components from XR Interaction Toolkit: TeleportationArea, TeleportationAnchor, TeleportationProvider. Basic implementation works out of the box, but for production we refine it in four steps:

1. Setting up XRRayInteractor with a curved ray (Bend Ray) — the teleportation arc looks more natural than a straight ray and is perceived better by users.
2. Adding a valid landing zone — a visual indicator changes color when hovering over an obstacle (red/green).
3. Implementing fade transition — smooth screen fade (black fade) before teleportation reduces disorientation.
4. Rotation snapping — after teleportation we offer snap rotation by 45° or 90° instead of smooth, reducing motion sickness risk.

For projects requiring smooth locomotion (action games, simulators), we use comfort settings: vignetting during movement, reducing FOV during acceleration. Settings are available to the user in the menu — different people have different sensitivity thresholds. The difference between kinematic and physics‑based movement: kinematic gives instant hand following but lets objects pass through walls; physics‑based via Joint provides realistic collisions but requires velocity damping and max joint force tuning. We choose based on the type of interaction.

How to make object grabbing in VR physically realistic?

This is the most underestimated part of VR development. Clients often perceive it as 'just hand animation', but in practice it is a complex system where physical correctness, responsiveness, and comfort conflict.

Grab (grabbing)

XR Interaction Toolkit provides three types of Interactable for grabbing:

• XRGrabInteractable — standard grab, object follows controller via physics joint or direct position/rotation
• XRSimpleInteractable — for objects without physical movement (buttons, levers)
• Custom Interactable by inheriting from XRBaseInteractable

Attach Transform — a frequently ignored detail. Each Interactable must have a properly configured Attach Transform (the point where the hand 'attaches'). Without it, the pistol grip will be at the center of the mesh, not where it is held.

For weapons and tools with two‑handed grab — a separate TwoHandGrab system: leading hand determines position, the second — orientation. XR Interaction Toolkit supports this via XRTwoHandGrabInteractable or custom logic with two Attach Points.

Throw (throwing)

Velocity smoothing is critical for realistic throwing because the Rigidbody.velocity at the moment of controller release reflects instantaneous speed, often incorrect due to tracking discretization. The user makes a quick wrist movement — but the object flies half as fast.

Solution: velocity smoothing over the last N frames (typically 5–10 frames, ~80–160 ms at 60 Hz) before release. XR Interaction Toolkit does this via VelocityEstimator. Additionally, we apply a velocity scaling multiplier — a small speed increase (1.2–1.5×) makes throws subjectively more satisfying. Angular velocity (for objects that should spin in flight) is also averaged similarly.

AR: Plane Tracking and Environment Interaction

AR adds a different class of problems — working with real, unpredictable environment. AR Foundation — a cross‑platform layer on top of ARKit and ARCore. Most basic features (plane detection, raycasting, image tracking, face tracking) are available through a unified API.

Plane Detection

ARPlaneManager detects horizontal and vertical planes. Practical nuances:

• Initialization takes time — the user must look around the room while the system builds a map. An explicit onboarding with instruction 'slowly move the camera across surfaces' is needed.
• Planes are unstable — their boundaries and position are updated as data accumulates. Objects placed on a plane need to be attached via parent to ARPlane, not to world coordinates.
• Plane merging — two detected floor segments may merge into one, moving the anchor. For critical anchors, use ARAnchor instead of direct attachment to the plane.

Image tracking (via ARTrackedImageManager) quality directly depends on the quality of reference images. Images with high detail frequency and contrasting edges (like a QR code but stylish) track more reliably than smooth logos. ARCore Geospatial API — for outdoor AR with real‑world coordinate binding (accuracy up to 10 cm in well‑mapped areas).

Optimization for VR: Frame Rate and Comfort

VR requires stable high frame rate. About 60% of development time in mobile VR goes to optimization, not functionality — retrofit costs twice as much as proper architecture from the first sprint.

Single Pass Instanced Rendering

The main render optimization in VR. Without it, the scene is rendered twice (once per eye), doubling draw calls. Single Pass Instanced renders both eyes in one pass via instancing: geometry is processed once, the shader gets two view/projection matrices through GPU instancing. Enabled in Unity via XR Plug-in Management > Rendering Mode: Single Pass Instanced. Important: custom shaders must support SPI — standard URP/HDRP shaders support it, custom HLSL requires modifications (UNITY_SETUP_STEREO_EYE_INDEX_POST_VERTEX and related macros). Applying this technique reduces draw calls by 40–50%, making it twice as efficient as naive double rendering.

Foveated Rendering

On Meta Quest, Fixed Foveated Rendering (FFR) is available — reducing resolution at the periphery where visual acuity is lower. Configured via OVRManager or Meta XR SDK:

OVRManager.fixedFoveatedRenderingLevel = OVRManager.FixedFoveatedRenderingLevel.High;
OVRManager.useDynamicFixedFoveatedRendering = true;

Dynamic FFR automatically increases the level when frame rate drops — more convenient than fixed in scenes with variable load.

IPD and Comfort Settings

IPD (Inter‑Pupillary Distance) — affects depth perception. At the programmable level on most devices, only reading IPD is available (OVRPlugin.GetSystemDisplayFrequency), physical adjustment is on the headset. For applications requiring precise positioning (medical simulators, training), we account for IPD in scene scale calculations.

Haptics

Haptic feedback — an underestimated tool. Even a simple vibration response when grabbing an object or hitting significantly increases the sense of presence. On average, integrating haptic patterns takes 30–80 hours per project.

XR Haptics via OpenXR:

var hapticImpulse = new UnityEngine.XR.HapticCapabilities();
InputDevice device = InputDevices.GetDeviceAtXRNode(XRNode.RightHand);
device.SendHapticImpulse(0, amplitude: 0.5f, duration: 0.1f);

For complex patterns (tactile 'texture' of a surface when touched, increasing vibration when drawing a bowstring) we use Meta Haptics Studio — allows designing haptic clips visually. This can reduce time spent on manual haptic tuning by about 30%.

What does VR/AR application development include?

When ordering a turnkey project, we provide the following deliverables:

• Architectural document with stack description, render logic, and interaction system
• Working prototype (MVP) for testing on target device
• Integration of necessary SDKs (Meta XR, OpenXR, AR Foundation, etc.)
• Optimization for target frequencies 72/90/120 Hz with draw call and FPS profiling
• Testing on physical hardware (Quest, SteamVR, HoloLens) with user involvement
• Full documentation for build, deployment, and support
• Training for the client's team (workshop on XR Toolkit)
• Warranty support for 1 month after delivery

What affects cost and timeline?

VR/AR projects are more expensive than regular games of similar scope. Iterations are slower — each fix must be tested in the headset, an emulator does not convey the real experience. Motion sickness forces reworking some conceptual decisions after the first playtest. Optimization takes a significant portion of time — for mobile VR (Quest) up to 60–70% of the cycle. For Quest projects, we start optimization from the first sprint. The cost of basic SDK integration (XR Interaction Toolkit) varies depending on the scope of custom Interactable. Typical budgets for a full Quest project range from $25,000 to $80,000 depending on complexity, number of custom interactions, and depth of optimization. Proper architectural planning from sprint one typically saves 40% on later rework compared to fixing performance bottlenecks retroactively.

Get a consultation on your project — we will assess the task, stack, and timelines. Order turnkey VR/AR application development with a guaranteed stable frame rate.