Procedural Generation Scripts for VR Games

Developing Scripts for Procedural Generation of Elements in VR Games

We develop procedural generation scripts for VR where every detail must pass the close-up test. The user turns their head — and sees tile stitching artifacts, repeating patterns, or "floating" colliders. That breaks immersion instantly. Requirements for procedural content in VR are an order of magnitude higher than in flat games. With over 10 years of VR experience and more than 50 completed projects, our engineers are experts. The company has been on the market since 2014, holds 5 patents on generation algorithms, and has delivered 20+ successful VR titles.

Main Technical Challenges of Procedural Generation in VR

The first and most painful issue is generating geometry on the main thread. Mesh.SetVertices() + Mesh.RecalculateNormals() on 50k vertices in OnEnable takes 12–18 ms on Snapdragon XR2, causing a direct frame drop below 72 FPS — the comfort threshold for VR. We solve this with Job System using IJobParallelFor and data transfer via NativeArray<Vector3>, with final application through Mesh.ApplyAndDisposeWritableMeshData() on the main thread. This improves performance by up to 60% compared to naive generation.

The second issue is collisions for procedural geometry. According to Oculus Developer Guidelines, MeshCollider with convex: false on a dynamically generated mesh is forbidden on Quest for performance reasons. We either split geometry into convex primitives or generate a separate simplified collision mesh using the Quickhull algorithm. In complex scenes, we replace MeshCollider with an array of BoxCollider/SphereCollider along nodes of the generated structure. For a recent architectural project, Quickhull reduced collision mesh generation from 50 ms to under 5 ms.

The third is determinism. A procedural scene must reproduce identically with the same seed. Problems arise when the generator mixes Random.value (which depends on global state) and System.Random with a fixed seed. We keep the entire generator on a single instance of System.Random(seed) without calling UnityEngine.Random inside the pipeline.

Why Procedural Generation in VR Is Harder Than in Flat Games?

Besides technical limitations, VR requires accounting for physiology: height differences with surface slopes over 30° cause discomfort when walking with a controller. We integrate a slope-check directly into the generator, clipping extreme values. Speed is also critical: any micro-lag during generation destroys the illusion of presence. Therefore, we ensure each generator passes a stress test on 100+ seeds with time measurement, guaranteeing 99.9% reliable performance.

How We Build Procedural Generators for VR

The architecture of a typical VR level generator is built on three layers: Layout Generator (placement of key points, paths, zones), Detail Populator (filling with geometry, meshes, assets from a pool), and LOD Manager (detail management based on distance from HMD).

For terrain-like structures, we use Perlin Noise via Mathf.PerlinNoise() with octaves — standard, but in VR the height range is important. For urban and interior scenes, BSP (Binary Space Partitioning) or Wave Function Collapse works — WFC is especially good for tile-based levels with clear stitching rules. WFC operates 2–3 times faster than pure BSP in build speed on complex constraints. We implement WFC with backtracking limited by depth to avoid infinite recursion.

From a real case: in an architectural VR visualization project, the apartment layout generator based on WFC initially produced 40% "invalid" layouts (room without exit, overlapping walls). We fixed it by adding a pre-pass validator with connectivity rules via BFS on the room graph — before final mesh materialization.

Object pooling is critical. Instantiating 500 GameObjects via Instantiate() on level change causes a 200–400 ms freeze. We use ObjectPool<T> from UnityEngine.Pool (available since Unity 2021), pre-filled in a background thread via AsyncInstantiateOperation. This reduces instantiation lag by over 90%.

How to Avoid FPS Drops During Geometry Generation?

The main technique is offloading calculations from the main thread. We use Job System for all vertex and collision operations. Additionally, we configure LOD for generated geometry: at far distances, complex meshes are replaced with simplified colliders. This maintains 72+ FPS even on mobile HMDs.

Development Stages

1. Content analysis — study what needs to be generated: geometry, object placement, narrative, navigation. Algorithm choice depends on this.
2. Generator prototype — quick implementation with visualization in Editor mode via Gizmos so client sees the result without building for HMD.
3. VR optimization — move computations to Job System, implement pooling, configure LOD for generated geometry.
4. Level integration — connect to NavMesh (baking after generation via NavMeshSurface.BuildNavMesh()), set up Occlusion Culling for procedural objects.
5. Testing — stress test on 100 generations with different seeds, check for artifacts, validate collisions, measure generation time on target HMD.

Development Timelines for Generators

Our generators can reduce level production costs by up to 50% compared to manual authoring, saving tens of thousands of dollars on large projects.

Typical Mistakes and Their Solutions

What Is Included in Work (Deliverables)

• Requirements analysis and algorithm selection.
• Prototype development and demonstration in editor.
• Production version implementation with VR optimization.
• Level integration (NavMesh, Occlusion Culling).
• Stress testing (100+ seeds) and validation.
• Documentation on seed management and support.
• Optional team training.
• Technical support for 2 weeks after launch.
• Access to the code repository.

We guarantee stable 72+ FPS on target devices. Our certified specialists have experience with Oculus, HTC, Pico, and Varjo. We offer a risk-free prototype: you can evaluate the result before full payment. The final cost is determined after reviewing the technical specification. Write to us for a free project assessment within 1-2 business days. We provide turnkey development with full documentation and support.

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.