Color and size over lifetime in Unity

Introduction

Changing color and size over lifetime helps make effects look alive and natural. It adds smooth changes as things grow or fade.

When making a fire particle that changes from bright yellow to dark smoke

When creating a magic spell that grows bigger and changes color as it fades

When animating a bubble that grows and becomes transparent before popping

When designing rain drops that shrink and disappear as they fall

Syntax

Unity

ParticleSystem.MainModule main = particleSystem.main;
main.startColor = new ParticleSystem.MinMaxGradient(Color.white, Color.red);
main.startSize = new ParticleSystem.MinMaxCurve(1f, 3f);

ParticleSystem.ColorOverLifetimeModule colorOverLifetime = particleSystem.colorOverLifetime;
colorOverLifetime.enabled = true;
colorOverLifetime.color = new ParticleSystem.MinMaxGradient(
    new Gradient() {
        colorKeys = new GradientColorKey[] {
            new GradientColorKey(Color.white, 0f),
            new GradientColorKey(Color.red, 1f)
        },
        alphaKeys = new GradientAlphaKey[] {
            new GradientAlphaKey(1f, 0f),
            new GradientAlphaKey(0f, 1f)
        }
    }
);

ParticleSystem.SizeOverLifetimeModule sizeOverLifetime = particleSystem.sizeOverLifetime;
sizeOverLifetime.enabled = true;
sizeOverLifetime.size = new ParticleSystem.MinMaxCurve(1f, AnimationCurve.Linear(0f, 1f, 1f, 0f));

Use colorOverLifetime.enabled = true to activate color changes over time.

Gradients define how color and transparency change from start (0) to end (1) of particle life.

Examples

This sets all particles to stay red during their lifetime.

Unity

var colorOverLifetime = particleSystem.colorOverLifetime;
colorOverLifetime.enabled = true;
colorOverLifetime.color = Color.red;

This makes particles grow from half size to double size over their life.

Unity

var sizeOverLifetime = particleSystem.sizeOverLifetime;
sizeOverLifetime.enabled = true;
sizeOverLifetime.size = AnimationCurve.Linear(0f, 0.5f, 1f, 2f);

This smoothly changes particle color from yellow to black and fades out transparency.

Unity

Gradient gradient = new Gradient();
gradient.colorKeys = new GradientColorKey[] {
    new GradientColorKey(Color.yellow, 0f),
    new GradientColorKey(Color.black, 1f)
};
gradient.alphaKeys = new GradientAlphaKey[] {
    new GradientAlphaKey(1f, 0f),
    new GradientAlphaKey(0f, 1f)
};

var colorOverLifetime = particleSystem.colorOverLifetime;
colorOverLifetime.enabled = true;
colorOverLifetime.color = new ParticleSystem.MinMaxGradient(gradient);

Sample Program

This script changes particles from white to blue and shrinks them to zero size as they live.

Unity

using UnityEngine;

public class ColorSizeOverLifetime : MonoBehaviour
{
    public ParticleSystem particleSystem;

    void Start()
    {
        var main = particleSystem.main;
        main.startColor = Color.white;
        main.startSize = 1f;

        var colorOverLifetime = particleSystem.colorOverLifetime;
        colorOverLifetime.enabled = true;

        Gradient gradient = new Gradient();
        gradient.colorKeys = new GradientColorKey[] {
            new GradientColorKey(Color.white, 0f),
            new GradientColorKey(Color.blue, 1f)
        };
        gradient.alphaKeys = new GradientAlphaKey[] {
            new GradientAlphaKey(1f, 0f),
            new GradientAlphaKey(0f, 1f)
        };

        colorOverLifetime.color = new ParticleSystem.MinMaxGradient(gradient);

        var sizeOverLifetime = particleSystem.sizeOverLifetime;
        sizeOverLifetime.enabled = true;
        sizeOverLifetime.size = new ParticleSystem.MinMaxCurve(1f, AnimationCurve.Linear(0f, 1f, 1f, 0f));
    }
}

Important Notes

Always enable the colorOverLifetime and sizeOverLifetime modules to see changes.

Use gradients to control smooth color and transparency changes.

Animation curves let you customize size changes over time easily.

Summary

Color and size over lifetime make particles look natural and dynamic.

Enable and set gradients or curves to control these changes.

Use this to create effects like fading, growing, or color shifting.