Raining at Night – Shader-Based Rain Simulation in Unity

Objective:

This project focuses on creating a stylized but believable rain effect using Shader Graph and Unity’s particle system. The goal was to simulate how raindrops interact with surfaces, adding depth and atmosphere to a night-time street scene without relying on costly visual effects.

Rainfall Particle System

Overview:
A custom particle system was built to simulate rain falling across the environment, with adjustable parameters for different weather intensities.

What it does:

  • Controls particle speed, direction, gravity, and wind to simulate anything from light rain to a storm

  • Integrates naturally into night-time lighting and reflections

  • Easily adaptable across different scenes or level settings

Best suited for:
Dynamic weather systems, moody cinematic scenes, atmospheric environments

Raindrop Impact Shader

Overview:
To enhance the sense of interaction between the rain and the environment, a shader was developed to simulate raindrops hitting and bouncing off surfaces. The challenge was to create the illusion of impact without using real-time physics or heavy simulations.

What it does:

  • Generates randomized splash effects on surfaces as rain “hits” them

  • Varies drop size and speed to avoid visual repetition

  • Maintains performance by faking interaction rather than calculating collisions

Performance Consideration:
While the effect isn’t physically accurate at close range, it reads well from a gameplay or cinematic camera distance — striking a balance between visual quality and GPU efficiency.

Best suited for:
Low-cost environmental FX, large outdoor scenes, background weather visuals

Summary

Both the rain particles and the impact shader were developed using Unity Shader Graph and the built-in particle system. The solution focuses on being visually expressive and resource-efficient, making it ideal for stylized games or levels where atmosphere matters. The system is modular and reusable, allowing for quick adjustments based on scene requirements, camera behavior, or overall art direction.