Design

Ray casting specs

Updated: May 6, 2026

This guide provides detailed specs behind ray casting interactions. These technical parameters control how the laser beam appears, how the cursor behaves at distance, when the ray auto-hides, and how the system picks the right target. Understanding these values helps you tune and replicate familiar ray behaviors in your app.

Ray length

The system uses two different lengths for ray casting. The hit-test ray is an invisible line that extends far from the user’s hand or controller to detect interactable surfaces. The visible laser beam is much shorter, extending only partway from the hand to the hit point. This separation lets the system detect targets at range without drawing a long beam across the entire scene.

Key details

Parameter	Value	Description
Hit-test ray length	10.0 m	The invisible ray that detects interactable surfaces. Targets beyond this distance are not detected.
Visual beam length (hands)	0.25 m	The visible laser extends 25 cm from the hand toward the target
Visual beam length (controllers)	0.35 m	The visible laser extends 35 cm from the controller toward the target

The visual beam extends from the hand or controller to the hit point, or to the maximum visual length, whichever is shorter. If the ray hits a surface 15 cm away, the beam stops there.

Designing for the length difference

Because the hit-test ray extends much farther than the visible beam, the user can target objects without seeing a laser connecting them. The cursor on the target surface is the primary visual indicator for distant interactions, not the beam itself.

Laser appearance

The laser beam provides visual feedback about the current interaction state. It changes color when the user selects a target and has different widths depending on the display context.

Key details

Parameter	Value	Description
Beam color (hovering)	White (#FFFFFF)	Default beam color when pointing at an interactable surface
Beam color (selecting)	Dark blue (#001E78)	Beam color when the user is pinching or holding the trigger
Beam width (Home)	0.0005 m	The beam is 0.5 mm wide in the Home environment
Beam width (Overlay)	0.001 m	The beam is 1 mm wide in Overlay mode, slightly thicker for visibility
Beam Z offset	0.1 m	A 10 cm gap between the hand and the start of the beam prevents visual clipping

Near-surface fade

When the user’s hand approaches a surface, the laser fades to transition smoothly to direct touch. For hands, the beam fades out over the last 5 cm before the surface. Controllers do not fade near surfaces.

Parameter	Value
Hand panel Z fade	0.05 m
Controller panel Z fade	0.0 m

Cursor

The cursor appears at the point where the ray intersects an interactable surface. It uses depth-compensated scaling so it maintains a consistent apparent size regardless of distance. The cursor also changes size and color to indicate interaction state.

Key details

Parameter	Value	Description
Apparent size	Constant angular size	The cursor uses depth-compensated scaling, so it appears the same size to the user regardless of how far the targeted surface is.
State-based scaling	Hovering ring is the baseline; selecting ring shrinks to roughly 83% of the hovering size	The ring contracts when the user pinches or pulls the trigger, providing a clear visual signal of engagement.
Color (hovering)	White (#FFFFFF)	Matches the laser beam color in the hovering state
Color (selecting)	Dark blue (#001E78)	Matches the laser beam color in the selecting state

For hand input, the cursor radius interpolates linearly with pinch strength. As the user brings their index finger and thumb closer together, the cursor smoothly transitions from the hovering radius to the selecting radius.

Transition timings

The cursor uses different transition durations for different state changes. Faster transitions for press and release give the interaction a responsive feel, while slower transitions for hover and removal avoid jarring visual changes.

Transition	Duration
Hover highlight (color change)	0.3 s
Press (pinch or trigger)	0.08 s
Release (pinch or trigger)	0.1 s
Cursor removal fade	0.5 s
Poke activation fade	0.1 s

Disambiguation

When the user’s ray passes near multiple interactable surfaces, the system needs to pick the right one. It uses a distance threshold and a priority score to avoid flickering between adjacent targets.

Key details

Parameter	Value	Description
Equal distance threshold	0.01 m	When two surfaces are within 1 cm of each other along the ray, the system treats them as equally close
Tiebreaker score	0 (default)	When surfaces are equally close, the higher tiebreaker score wins. Set per interactable.

The system always selects the closest hit along the ray. The equal distance threshold and tiebreaker score only apply when two surfaces are nearly the same distance away. This prevents the cursor from flickering between overlapping elements.

Using tiebreaker scores

Assign higher tiebreaker scores to interactive elements that should take priority when they overlap with other surfaces. For example, a button rendered on top of a scrollable panel should have a higher score than the panel itself.

Ray auto-hide and disable

The ray is disabled (and the laser fades from view) in situations where it would conflict with another interaction or has nothing to act on. While the ray is disabled the user cannot select with it, even if the laser is mid-fade. The ray reactivates automatically when the conflict clears or a valid target is back in range.

When the ray disables

Poke active on the same hand. The poke takes over interaction. The fade uses an asymmetric curve that starts at 60% of the poke timeline and completes before contact.

Direct grab active. The direct grab owns the interaction. The laser hides so it does not obscure the grabbed object.

Pointing away from surfaces. When the ray is not aimed at any interactable, the beam fades to avoid drawing a floating laser into empty space. The fade begins at 50 cm from the nearest surface.

Teleporting. Teleport locomotion takes over input.

Device disconnected. The laser fades out over 0.25 seconds rather than disappearing instantly.

Head ray visibility

The head ray (fallback mode) shows only a cursor on the target surface. The laser beam is not drawn for head ray interactions.

Fade timing

Parameter	Value
Default fade duration	0.25 s
Disconnect fade	0.25 s
Length fade threshold	0.1 m (beam fades below 10 cm length)

Head ray timing

When the headset has no external input available (no hands detected, no controller connected), the system falls back to the head ray. The head ray uses the center of the user’s field of view for targeting and the headset buttons for selection. There is a delay before the head ray activates to avoid false activation during brief hand tracking interruptions.

Key details

Parameter	Value	Description
Activation delay	20.0 s	The system waits 20 seconds after losing all external input before activating the head ray
Recently active window	30.0 s	Once the head ray has been used, it stays available for 30 seconds after the last interaction
Suppression timeout	0.5 s	Brief suppression window during input mode transitions to prevent accidental activation

Designing for head ray

If your app supports headset-only input, plan for the 20-second activation delay. Consider providing visual feedback that tells the user the head ray is about to become available. The delay prevents false activations but may confuse users who expect immediate input.

Affordances

The system provides haptic and audio feedback at key moments during ray interactions. These affordances are automatic and help the user confirm that their targeting and selection registered.

State	Affordances
Hover	Haptic: System hover effect. No audio.
Select	Haptic: System press effect. Audio: 3D-positioned click sound at the hit point.
Release	No dedicated haptic or audio feedback.