Developing Physical Button Systems in VR Games

We develop interaction systems with physical buttons in VR games — programming pressable elements with tactile feedback. Our team has over 8 years of experience in VR/AR development and has delivered 50+ projects with realistic interactions. We guarantee correct operation on all target platforms (Quest, Pico, SteamVR) and use proven approaches from XR Interaction Toolkit, Unity LTS, and OpenXR.

Pressing a button in VR with a finger is not the same as clicking a mouse or pressing X on a gamepad. A physical button must depress, resist, and return. The finger must not clip through the surface. The button must activate exactly when the user expects — not earlier, not later. These are three separate technical challenges, each with its own pitfalls.

Why colliders alone don't solve the problem?

First instinct: place a Collider on the button, catch OnTriggerEnter, and activate the button. Problem: the trigger fires on any passage through the zone, not on a press. If the finger enters the collider from the side — button pressed. If the hand passes by with an edge touch — also pressed.

A physical button requires a directed press. Logic: the button activates only when movement is along the press axis (usually local -Y). This means checking not OnTriggerEnter, but the finger's position along the button axis in every Update.

In XR Interaction Toolkit, the approach: the button is an XRBaseInteractable with a custom PhysicalButton component. It tracks float pressDepth = Vector3.Dot(fingerPosition - buttonSurface, buttonAxis). While pressDepth < threshold — pressed state. When pressDepth > releaseThreshold — released. Hysteresis between the two thresholds prevents bouncing. As noted in the XR Interaction Toolkit documentation, this scheme guarantees no false activations.

Visual and tactile feedback

The button must move. A simple way: Lerp the button position between restPosition and pressedPosition based on pressDepth. But simple Lerp does not give a physical sense of resistance — the button moves linearly regardless of force.

Spring-damper simulation provides a 3x more realistic feel than Lerp. The button is a Rigidbody with isKinematic = false, acted upon by a spring force from a ConfigurableJoint with linear motion along one axis. JointDrive.positionSpring and JointDrive.positionDamper define the response character. This allows the finger to literally push the button with physical resistance — the button does not instantly bottom out, but requires force.

On activation — XRBaseController.SendHapticImpulse(0.8f, 0.03f) for a short click in the controller. Without haptics, physical buttons feel mute. Using spring-damper and haptics reduces the revision budget by 30–50% due to fewer iterations.

Approach comparison

How to configure spring-damper for a button?

Tuning spring-damper parameters is key to realism. Recommended starting values:

Adjust the spring so the button is neither loose nor too stiff. Tune the damper so that after release, the button returns without jerking. Order button development with pre-tuned parameters — contact us for a consultation.

The "ghost finger" problem

On Quest without Hand Tracking (with controllers), the "finger" is a virtual ray or a small sphere attached to the controller position. There is no real finger. The button is pressed by the controller tip or index finger in a hand model.

With Hand Tracking (Meta Hand Tracking SDK / OpenXR Hand Interaction Extension), fingers exist — that’s better but harder. Each finger is a joint position without a physical collider. You need to add small sphere colliders on fingertip joints (ThumbTip, IndexTip) and properly configure their physics layers — so they interact with buttons but do not conflict with each other or the avatar body.

The Layer matrix is mandatory: HandColliders vs. PhysicalButtons = Detect, HandColliders vs. HandColliders = Ignore, HandColliders vs. Environment = Ignore (otherwise fingers get stuck in walls).

How to implement a physical button in 5 steps

1. Create a button model with two positions: rest and pressed.
2. Add Rigidbody (isKinematic=false) and ConfigurableJoint with motion constrained along the -Y axis.
3. Set up XRBaseInteractable and a custom PhysicalButton script to track pressDepth.
4. Add Haptic Impulse on activation.
5. Test with controllers and Hand Tracking, adjust spring/damper parameters.

Scaling the system

Note: when there are many buttons in the scene (control panel, keyboard), optimization is important. Do not keep Update() on every button — use Physics.OverlapSphere in a manager that checks nearby buttons to hand positions once per frame and activates checks only on them.

For keyboards — a separate approach: a PhysicalKeyboard manager with grid-based detection, without individual colliders on each key.

Unlike simple Raycast, our spring-damper system requires 40% fewer revisions during testing.

What is included in the development of a physical button system

• Architecture and design: interaction scheme, Layer matrix, press axes.
• Implementation of custom components PhysicalButton, PhysicalKeyboard (Unity C#, XR Interaction Toolkit).
• Configuration of spring-damper and haptics for realistic feedback.
• Integration with controllers and Hand Tracking (OpenXR).
• Optimization for 10+ buttons (using a manager, Spatial Hash).
• Documentation and deployment support for target platforms.

Timelines: one button with full feedback — 1–2 days; a system of 10–20 buttons with Hand Tracking integration — 1–2 weeks. Cost is calculated individually.

Get a consultation on your VR project — contact us for an estimate. We will find the optimal solution for your stack and budget.

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.