Rain simulates and renders realistic precipitation within the 3D stage volume. Raindrops naturally stretch along their motion vector into angled streaks based on falling speed and wind direction, producing realistic splashes upon hitting the avatar, props, or the floor before recycling back to the top.
Rain and Snow are rendered as genuine 3D particles in space, possessing authentic depth and occlusion rather than acting as a flat screen overlay.
OriginalEffectControls
| Control | Range | Default | Description |
|---|---|---|---|
| Amount | 100 – 10000 | 4000 | Total raindrops simulated in the stage |
| Speed | ×0.2 – ×3 | ×1 | Downward fall speed multiplier |
| Wind | −6 – 6 m/s | 0 m/s | Lateral wind speed blowing across the stage |
| Drop Length | 0.2 – 3 | 1 | Length multiplier stretching raindrops along their path |
| Drop Width | 0.4 – 3 | 1 | Thickness of rain streaks |
| Splashes | 0 – 1 | 0.7 | Intensity of impact splashes (0 immediately removes on impact) |
| Opacity | 0.05 – 1 | 0.4 | Overall rendering opacity of streaks and splashes |
The baseline speed of ×1 provides a natural fall rate. Setting speed too high may cause streaks to flash across the screen too quickly to discern clearly.
Wind and Streak Dynamics
Wind causes raindrops to drift laterally and tilts their angle organically. The angle of the rain naturally aligns with both gravity and wind, creating convincing slanting rain curtains as wind increases.
Wind speed is measured in meters per second (m/s) independently of vertical Speed. To simulate a stormy downpour, increase Wind past 4 m/s, lengthen Drop Length, and lower Opacity slightly to produce a dense angled rain veil.
Raindrops that exit the viewport wrap around and re-enter from the opposite side, keeping rain density uniform even under heavy winds.
Collision and Splashes
Rain features automatic collision detection, sensing the avatar, stage props, and the ground plane. When a raindrop hits a surface, it stops and spreads an outward splash ring conforming to the surface before dissipating after about one-third of a second.
Splashes lie flat against the contacted surface rather than facing the camera. From low camera angles, splashes on an avatar's head or shoulders compress realistically in perspective.
Setting Splashes to 0 recycles raindrops immediately upon contact without generating splash geometry, saving rendering performance.
3D Stage Integration
Because rain is rendered as true 3D elements within the stage:
- Self-Illumination: Rain uses a transmissive emissive material unaffected by dark scene lighting shadows, staying visible even in night scenes.
- Spatial Depth: Drops occupy real 3D coordinates, blurring correctly when Depth of Field is active and properly occluding behind or in front of the avatar.
- Post-Processing Support: The entire Effect Chain (such as bloom and color grading) naturally applies to rain.
Performance
Rain is simulated by an efficient GPU particle system. Collision detection is shared with Snow, so enabling both incurs no duplicate overhead.
Amount is the primary performance factor. Adjusting raindrop count via the slider is smooth, though higher particle counts require more graphics processing power.
When toggled on or off, rain smoothly fades in and out over roughly 0.4 seconds to prevent visual pop-in.
Rain requires GPU compute capability and is only available on the 3D stage. On unsupported fallback environments, rain safely disables itself to keep the stage running stably.
Last updated on November 3, 2026