Rain effects add dynamic weather elements to 3D scenes. This page explores techniques for creating realistic and performant rain visualizations.

Overview

Rain visualization involves creating thousands of falling particles that create the illusion of precipitation. The challenge is maintaining performance while creating a convincing effect.

Implementation Techniques

Particle System

Rain uses a particle system with:

• Vertical motion: Particles fall downward with gravity
• Randomized speeds: Each particle falls at slightly different rates
• Trail effects: Optional trails create streaks of rain
• Splash effects: Particles can create splashes on surfaces

Performance Optimization

Rain systems require careful optimization:

• Instanced rendering: Render many particles efficiently
• LOD system: Reduce particle count at distance
• Culling: Only render particles in view
• GPU acceleration: Use compute shaders when available

Visual Effects

Rain visualization can include:

• Streaks: Long vertical lines representing falling rain
• Splashes: Particle effects when rain hits surfaces
• Mist: Fog-like effects from heavy rain
• Reflections: Water reflections on surfaces

Shader Techniques

Rain shaders typically use:

• Alpha blending: For transparency
• Motion blur: For streak effects
• Depth testing: To ensure proper layering
• Billboarding: To face the camera

Related Articles

• 3d Background - Atmospheric Effects - Main atmospheric effects page
• 3d Background - Atmospheric Effects - Fog Visualization - Fog effects
• 3d Background - Atmospheric Effects - Snow Visualization - Snow effects
• The 3d background - Overview of the 3D background system