ParticleSystem.TrailModule.sizeAffectsWidth

Description

Set whether the particle size will act as a multiplier on top of the trail width.

Useful for making larger particles have wider trails.

using UnityEngine;
using System.Collections;

public class ExampleClass : MonoBehaviour
{
    private ParticleSystem ps;
    public bool sizeAffectsWidth = true;

    void Start()
    {
        ps = GetComponent<ParticleSystem>();

        var main = ps.main;
        main.startColor = new ParticleSystem.MinMaxGradient(Color.red, Color.yellow);
        main.startSize = new ParticleSystem.MinMaxCurve(0.01f, 1.0f);
        main.startLifetime = 1.5f;

        var trails = ps.trails;
        trails.enabled = true;

        var psr = GetComponent<ParticleSystemRenderer>();
        psr.trailMaterial = new Material(Shader.Find("Sprites/Default"));
    }

    void Update()
    {
        var trails = ps.trails;
        trails.sizeAffectsWidth = sizeAffectsWidth;
    }

    void OnGUI()
    {
        sizeAffectsWidth = GUI.Toggle(new Rect(25, 25, 200, 30), sizeAffectsWidth, "Size affects width");
    }
}