ParticleSystem.LightsModule.useParticleColor

Description

Toggle whether the particle lights multiply their color by the particle color.

Remember to also set your light color to white, if you want the lights to have the exact same color as the particles.

using UnityEngine;
using System.Collections;

// For best results, use Deferred Rendering (see Camera settings)
public class ExampleClass : MonoBehaviour
{
    private ParticleSystem ps;
    public Light lightPrefab;     // Provide a light Prefab in the inspector
    public float hSliderValueR = 1.0f;
    public float hSliderValueG = 1.0f;
    public float hSliderValueB = 1.0f;
    public float hSliderValueA = 1.0f;
    public bool useParticleColor = true;

    void Start()
    {
        ps = GetComponent<ParticleSystem>();
        ps.transform.localRotation = Quaternion.Euler(0.0f, 0.0f, 45.0f);

        var shape = ps.shape;
        shape.shapeType = ParticleSystemShapeType.Circle;

        var lights = ps.lights;
        lights.enabled = true;
        lights.light = lightPrefab;
        lights.ratio = 1.0f;
        lights.maxLights = 1000;

        // plane to receive lights
        var plane = GameObject.CreatePrimitive(PrimitiveType.Plane);
        plane.transform.parent = ps.transform;
        plane.transform.localPosition = new Vector3(0.0f, 0.0f, 3.0f);
        plane.transform.localScale = new Vector3(20.0f, 20.0f, 20.0f);
        plane.transform.localRotation = Quaternion.Euler(-90.0f, 0.0f, 0.0f);

        var material = new Material(Shader.Find("Standard"));
        material.color = new Color(0.1f, 0.1f, 0.1f, 1.0f);
        plane.GetComponent<MeshRenderer>().material = material;
    }

    void Update()
    {
        var lights = ps.lights;
        lights.useParticleColor = useParticleColor;

        var main = ps.main;
        main.startColor = new Color(hSliderValueR, hSliderValueG, hSliderValueB, hSliderValueA);
    }

    void OnGUI()
    {
        GUI.Label(new Rect(25, 40, 100, 30), "Red");
        GUI.Label(new Rect(25, 70, 100, 30), "Green");
        GUI.Label(new Rect(25, 100, 100, 30), "Blue");
        GUI.Label(new Rect(25, 130, 100, 30), "Alpha");

        hSliderValueR = GUI.HorizontalSlider(new Rect(95, 45, 100, 30), hSliderValueR, 0.0f, 1.0f);
        hSliderValueG = GUI.HorizontalSlider(new Rect(95, 75, 100, 30), hSliderValueG, 0.0f, 1.0f);
        hSliderValueB = GUI.HorizontalSlider(new Rect(95, 105, 100, 30), hSliderValueB, 0.0f, 1.0f);
        hSliderValueA = GUI.HorizontalSlider(new Rect(95, 135, 100, 30), hSliderValueA, 0.0f, 1.0f);

        useParticleColor = GUI.Toggle(new Rect(25, 175, 200, 30), useParticleColor, "Use Particle Color for Light Color");
    }
}