GPU Particles - A GPU-based particle simulation in Unity

Engine: Unity

Other Tech: compute shaders, geometry shaders

An implementation of particle systems in Unity on the GPU. This does not use Unity's built-in particle systems at all. Rather, it stores a list of all particles on the GPU, and uses a compute shader to update them one or more times per frame. The particles are rendered using a geometry shader to expand a point into a quad facing the camera, then a basic vertex/fragment shader.

Since the GPU is much more suited than the CPU to parallel operations on large amounts of data, our system enabled far more particles than a CPU-implemented solution. In our demo, we had over 1 million particles simulating at 60 FPS on a mid-to-high-end GPU.

There are several properties that can be controlled for each particle system:

• Emitter shape: box, sphere, cylinder, and arbitrary mesh
• Start color range and linear color animation
• Start size range and linear size animation
• Start velocity and linear speed animation
• Animate color based on speed
• Lifetime range
• Particle count
• Point gravity
• Local or world space simulation
• Sprite and sprite animation

This was my final project for the class Computer Animation, along with my teammate, Eric Cerini. I was responsible for most of the shader work in the compute and geometry shaders.