ParticleSystemRenderer.sortMode

Description

Specifies how to sort particles within a system.

using UnityEngine;
using UnityEditor;
using System.Collections;

public class ExampleClass : MonoBehaviour {

    private ParticleSystem ps;
    private ParticleSystemRenderer psr;
    public ParticleSystemSortMode sortMode;

    void Start() {

        ps = GetComponent<ParticleSystem>();
        psr = GetComponent<ParticleSystemRenderer>();

        // set a slow start speed and high emission rate, to cause more overlap, to show sorting
        var main = ps.main;
        main.startSpeedMultiplier = 0.2f;
        var emission = ps.emission;
        emission.rateOverTimeMultiplier = 100.0f;

        // set color over life, so we can see the sorting more easily
        var colorOverLifetime = ps.colorOverLifetime;
        colorOverLifetime.enabled = true;

        Gradient gradient = new Gradient();
        gradient.SetKeys(
            new GradientColorKey[] { new GradientColorKey(Color.green, 0.0f), new GradientColorKey(Color.red, 1.0f) },
            new GradientAlphaKey[] { new GradientAlphaKey(1.0f, 0.0f), new GradientAlphaKey(1.0f, 1.0f) }
            );

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

    void Update() {

        psr.sortMode = sortMode;
    }

    void OnGUI() {

        sortMode = (ParticleSystemSortMode)GUI.SelectionGrid(new Rect(25, 25, 900, 30), (int)sortMode, new GUIContent[] { new GUIContent("None"), new GUIContent("Distance"), new GUIContent("OldestInFront"), new GUIContent("YoungestInFront") }, 4);
    }
}