IJobParticleSystem.Execute

参数

描述

实现此方法可访问和修改粒子属性。

下面的脚本示例可用于将粒子吸引到提供的位置。

using System;
using Unity.Collections;
using UnityEngine;
using UnityEngine.ParticleSystemJobs;

public class ParticleJob : MonoBehaviour
{
    public float effectRange = 2.0f;
    public float effectStrength = 1.0f;
    public float oscillationSpeed = 12.0f;
    public bool useJobSystem = false;

    private float oscillationPhase;

    private ParticleSystem ps;
    private UpdateParticlesJob job = new UpdateParticlesJob();
    private ParticleSystem.Particle[] mainThreadParticles;

    private static float Remap(float x, float x1, float x2, float y1, float y2)
    {
        var m = (y2 - y1) / (x2 - x1);
        var c = y1 - m * x1;

        return m * x + c;
    }

    private static Vector3 CalculateVelocity(ref UpdateParticlesJob job, Vector3 delta)
    {
        float attraction = job.effectStrength / job.effectRangeSqr;
        return delta.normalized * attraction;
    }

    private static Color32 CalculateColor(ref UpdateParticlesJob job, Vector3 delta, Color32 srcColor, UInt32 seed)
    {
        var targetColor = new Color32((byte)(seed >> 24), (byte)(seed >> 16), (byte)(seed >> 8), srcColor.a);
        float lerpAmount = delta.magnitude * job.inverseEffectRange;
        lerpAmount = lerpAmount * 0.25f + 0.75f;
        return Color32.Lerp(targetColor, srcColor, lerpAmount);
    }

    void Start()
    {
        ps = GetComponent<ParticleSystem>();
        oscillationPhase = UnityEngine.Random.Range(0.0f, Mathf.PI * 2.0f);
    }

    void Update()
    {
        Vector2 mouse = Input.mousePosition;
        job.effectPosition = Camera.main.ScreenToWorldPoint(new Vector3(mouse.x, mouse.y, -Camera.main.transform.position.z));
        job.effectRangeSqr = effectRange * effectRange;
        job.effectStrength = effectStrength * Remap(Mathf.Sin(oscillationPhase + Time.time * oscillationSpeed), -1, 1, -1, 0.5f);
        job.inverseEffectRange = (1.0f / effectRange);

        if (!useJobSystem)
        {
            if (mainThreadParticles == null)
                mainThreadParticles = new ParticleSystem.Particle[ps.main.maxParticles];

            var count = ps.GetParticles(mainThreadParticles);
            for (int i = 0; i < count; i++)
            {
                Vector3 position = mainThreadParticles[i].position;
                Vector3 delta = position - job.effectPosition;
                if (delta.sqrMagnitude < job.effectRangeSqr)
                {
                    mainThreadParticles[i].velocity += CalculateVelocity(ref job, delta);
                    mainThreadParticles[i].startColor = CalculateColor(ref job, delta, mainThreadParticles[i].startColor, mainThreadParticles[i].randomSeed);
                }
            }
            ps.SetParticles(mainThreadParticles, count);
        }
    }

    void OnParticleUpdateJobScheduled()
    {
        if (useJobSystem)
            job.Schedule(ps);
    }

    struct UpdateParticlesJob : IJobParticleSystem
    {
        [ReadOnly]
        public Vector3 effectPosition;

        [ReadOnly]
        public float effectRangeSqr;

        [ReadOnly]
        public float effectStrength;

        [ReadOnly]
        public float inverseEffectRange;

        public void Execute(ParticleSystemJobData particles)
        {
            var positionsX = particles.positions.x;
            var positionsY = particles.positions.y;
            var positionsZ = particles.positions.z;

            var velocitiesX = particles.velocities.x;
            var velocitiesY = particles.velocities.y;
            var velocitiesZ = particles.velocities.z;

            var colors = particles.startColors;

            var randomSeeds = particles.randomSeeds;

            for (int i = 0; i < particles.count; i++)
            {
                Vector3 position = new Vector3(positionsX[i], positionsY[i], positionsZ[i]);
                Vector3 delta = (position - effectPosition);
                if (delta.sqrMagnitude < effectRangeSqr)
                {
                    Vector3 velocity = CalculateVelocity(ref this, delta);

                    velocitiesX[i] += velocity.x;
                    velocitiesY[i] += velocity.y;
                    velocitiesZ[i] += velocity.z;

                    colors[i] = CalculateColor(ref this, delta, colors[i], randomSeeds[i]);
                }
            }
        }
    }
}

将此处的脚本与上面的示例结合使用可提供鼠标位置作为吸引粒子的点。

using UnityEditor;
using UnityEngine;

public class ParticleSpawner : MonoBehaviour
{
    public ParticleSystem prefab;
    public int systemCount = 128;
    public int particleEmissionRatePerSystem = 400;
    public float particleSystemShapeRadius = 1.0f;
    public float totalRadius = 5.0f;
    public float effectRange = 3.0f;
    public float effectStrength = 1.0f;
    public float oscillationSpeed = 10.0f;
    public bool hasTrails = true;
    public bool useJobSystem = false;

    void Start()
    {
        var material = new Material(Shader.Find("Legacy Shaders/Particles/Additive"));
        material.SetTexture("_MainTex", AssetDatabase.GetBuiltinExtraResource<Texture2D>("Default-Particle.psd"));

        for (int i = 0; i < systemCount; i++)
        {
            var go = GameObject.Instantiate(prefab);
            var ps = go.GetComponent<ParticleSystem>();

            go.GetComponent<ParticleSystemRenderer>().sharedMaterial = material;

            float x = (float)i / systemCount;
            float theta = x * Mathf.PI * 2;

            var transform = go.GetComponent<Transform>();
            transform.position = new Vector3(Mathf.Sin(theta), Mathf.Cos(theta), 0.0f) * totalRadius;

            var main = ps.main;
            main.startColor = Color.HSVToRGB(x, Random.Range(0.5f, 1.0f), Random.Range(0.5f, 1.0f));

            var emission = ps.emission;
            emission.rateOverTime = particleEmissionRatePerSystem;

            var shape = ps.shape;
            shape.radius = particleSystemShapeRadius;

            var trails = ps.trails;
            trails.enabled = hasTrails;

            var updateJob = go.GetComponent<ParticleJob>();
            updateJob.effectRange = effectRange;
            updateJob.effectStrength = effectStrength;
            updateJob.oscillationSpeed = oscillationSpeed;
            updateJob.useJobSystem = useJobSystem;
        }
    }

    // UI
    void OnGUI()
    {
        float x = 25.0f;
        float y = 60.0f;
        float spacing = 40.0f;

        EditorGUI.BeginChangeCheck();

        GUIStyle backgroundStyle = new GUIStyle(GUI.skin.box);
        backgroundStyle.normal.background = Texture2D.whiteTexture;
        var oldColor = GUI.backgroundColor;
        GUI.backgroundColor = new Color(0.5f, 0.5f, 0.5f, 0.5f);
        GUI.Box(new Rect(x - 10, y - 35, 260, 230), "Options", backgroundStyle);
        GUI.backgroundColor = oldColor;

        GUI.Label(new Rect(x, y, 140, 30), "Effect Range");
        effectRange = GUI.HorizontalSlider(new Rect(x + 140, y + 5, 100, 30), effectRange, 0.0f, 10.0f);
        y += spacing;

        GUI.Label(new Rect(x, y, 140, 30), "Effect Strength");
        effectStrength = GUI.HorizontalSlider(new Rect(x + 140, y + 5, 100, 30), effectStrength, 0.0f, 10.0f);
        y += spacing;

        GUI.Label(new Rect(x, y, 140, 30), "Oscillation Speed");
        oscillationSpeed = GUI.HorizontalSlider(new Rect(x + 140, y + 5, 100, 30), oscillationSpeed, 0.0f, 20.0f);
        y += spacing;

        hasTrails = GUI.Toggle(new Rect(x, y + 5, 140, 30), hasTrails, "Trails");
        y += spacing;

        useJobSystem = GUI.Toggle(new Rect(x, y + 5, 140, 30), useJobSystem, "Use C# Job System");
        y += spacing;

        if (EditorGUI.EndChangeCheck())
        {
            ParticleJob[] updateJobs = GameObject.FindObjectsOfType<ParticleJob>();
            for (int i = 0; i < updateJobs.Length; i++)
            {
                var updateJob = updateJobs[i];
                updateJob.effectRange = effectRange;
                updateJob.effectStrength = effectStrength;
                updateJob.oscillationSpeed = oscillationSpeed;
                updateJob.useJobSystem = useJobSystem;

                var ps = updateJob.GetComponent<ParticleSystem>();

                var trails = ps.trails;
                trails.enabled = hasTrails;
            }
        }
    }
}