ParticleSystemForceField

Description

Script interface for Particle System Force Fields.

Particle System Force Fields can be used to influence groups of particles that enter each field's zone of influence.

The shape of the Force Field can be set to a variety of shapes, and how the particles are affected is controlled by various properties in the Force Field.

As part of choosing the shape, you may define a start and end range. The end range describes the maximum extent of the shape, and the start range can be used to create a hollow shape.

A number of forces can be applied to particles that are within this volume: directional, gravitational, rotational, drag, and a vector field.

The settings for each type of force make use of the MinMaxCurve type, which is also used in the Particle System. This type allows you to set simple uniform values, or more complicated values that vary per-particle, and vary over the lifetime of each particle.

using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using UnityEngine;

[RequireComponent(typeof(ParticleSystem))]
public class ExampleClass : MonoBehaviour
{
    public ParticleSystemForceFieldShape m_Shape = ParticleSystemForceFieldShape.Sphere;
    public float m_StartRange = 0.0f;
    public float m_EndRange = 3.0f;
    public Vector3 m_Direction = Vector3.zero;
    public float m_Gravity = 0.0f;
    public float m_GravityFocus = 0.0f;
    public float m_RotationSpeed = 0.0f;
    public float m_RotationAttraction = 0.0f;
    public Vector2 m_RotationRandomness = Vector2.zero;
    public float m_Drag = 0.0f;
    public bool m_MultiplyDragByParticleSize = false;
    public bool m_MultiplyDragByParticleVelocity = false;

    private ParticleSystemForceField m_ForceField;

    void Start()
    {
        // Create a Force Field
        var go = new GameObject("ForceField", typeof(ParticleSystemForceField));
        go.transform.position = new Vector3(0, 2, 0);
        go.transform.rotation = Quaternion.Euler(new Vector3(90.0f, 0.0f, 0.0f));

        m_ForceField = go.GetComponent<ParticleSystemForceField>();

        // Configure Particle System
        transform.position = new Vector3(0, -4, 0);
        transform.rotation = Quaternion.identity;
        var ps = GetComponent<ParticleSystem>();

        var main = ps.main;
        main.startSize = new ParticleSystem.MinMaxCurve(0.05f, 0.2f);
        main.startSpeed = new ParticleSystem.MinMaxCurve(1.5f, 2.5f);
        main.maxParticles = 100000;

        var emission = ps.emission;
        emission.rateOverTime = 0.0f;
        emission.burstCount = 1;
        emission.SetBurst(0, new ParticleSystem.Burst(0.0f, 200, 200, -1, 0.1f));

        var shape = ps.shape;
        shape.shapeType = ParticleSystemShapeType.SingleSidedEdge;
        shape.radius = 5.0f;
        shape.radiusMode = ParticleSystemShapeMultiModeValue.BurstSpread;
        shape.randomPositionAmount = 0.1f;
        shape.randomDirectionAmount = 0.05f;

        var forces = ps.externalForces;
        forces.enabled = true;
    }

    void Update()
    {
        m_ForceField.shape = m_Shape;
        m_ForceField.startRange = m_StartRange;
        m_ForceField.endRange = m_EndRange;
        m_ForceField.directionX = m_Direction.x;
        m_ForceField.directionY = m_Direction.y;
        m_ForceField.directionZ = m_Direction.z;
        m_ForceField.gravity = m_Gravity;
        m_ForceField.gravityFocus = m_GravityFocus;
        m_ForceField.rotationSpeed = m_RotationSpeed;
        m_ForceField.rotationAttraction = m_RotationAttraction;
        m_ForceField.rotationRandomness = m_RotationRandomness;
        m_ForceField.drag = m_Drag;
        m_ForceField.multiplyDragByParticleSize = m_MultiplyDragByParticleSize;
        m_ForceField.multiplyDragByParticleVelocity = m_MultiplyDragByParticleVelocity;
    }

    void OnGUI()
    {
        GUIContent[] shapeLabels = Enum.GetNames(typeof(ParticleSystemForceFieldShape)).Select(n => new GUIContent(n)).ToArray();
        m_Shape = (ParticleSystemForceFieldShape)GUI.SelectionGrid(new Rect(25, 25, 400, 25), (int)m_Shape, shapeLabels, 4);

        float y = 80.0f;
        float spacing = 40.0f;

        GUI.Label(new Rect(25, y, 140, 30), "Start Range");
        m_StartRange = GUI.HorizontalSlider(new Rect(165, y + 5, 100, 30), m_StartRange, 0.0f, 2.0f);
        y += spacing;

        GUI.Label(new Rect(25, y, 140, 30), "End Range");
        m_EndRange = GUI.HorizontalSlider(new Rect(165, y + 5, 100, 30), m_EndRange, 2.0f, 3.0f);
        y += spacing;

        GUI.Label(new Rect(25, y, 140, 30), "Direction");
        m_Direction.x = GUI.HorizontalSlider(new Rect(165, y + 5, 40, 30), m_Direction.x, -1.0f, 1.0f);
        m_Direction.y = GUI.HorizontalSlider(new Rect(210, y + 5, 40, 30), m_Direction.y, -1.0f, 1.0f);
        m_Direction.z = GUI.HorizontalSlider(new Rect(255, y + 5, 40, 30), m_Direction.z, -1.0f, 1.0f);
        y += spacing;

        GUI.Label(new Rect(25, y, 140, 30), "Gravity");
        m_Gravity = GUI.HorizontalSlider(new Rect(165, y + 5, 100, 30), m_Gravity, -0.05f, 0.05f);
        y += spacing;

        GUI.Label(new Rect(25, y, 140, 30), "Gravity Focus");
        m_GravityFocus = GUI.HorizontalSlider(new Rect(165, y + 5, 100, 30), m_GravityFocus, 0.0f, 1.0f);
        y += spacing;

        GUI.Label(new Rect(25, y, 140, 30), "Rotation Speed");
        m_RotationSpeed = GUI.HorizontalSlider(new Rect(165, y + 5, 100, 30), m_RotationSpeed, -10.0f, 10.0f);
        y += spacing;

        GUI.Label(new Rect(25, y, 140, 30), "Rotation Attraction");
        m_RotationAttraction = GUI.HorizontalSlider(new Rect(165, y + 5, 100, 30), m_RotationAttraction, 0.0f, 0.01f);
        y += spacing;

        GUI.Label(new Rect(25, y, 140, 30), "Rotation Randomness");
        m_RotationRandomness.x = GUI.HorizontalSlider(new Rect(165, y + 5, 60, 30), m_RotationRandomness.x, 0.0f, 1.0f);
        m_RotationRandomness.y = GUI.HorizontalSlider(new Rect(230, y + 5, 60, 30), m_RotationRandomness.y, 0.0f, 1.0f);
        y += spacing;

        GUI.Label(new Rect(25, y, 140, 30), "Drag");
        m_Drag = GUI.HorizontalSlider(new Rect(165, y + 5, 100, 30), m_Drag, 0.0f, 20.0f);
        y += spacing;

        m_MultiplyDragByParticleSize = GUI.Toggle(new Rect(25, y, 220, 30), m_MultiplyDragByParticleSize, "Multiply Drag by Particle Size");
        y += spacing;

        m_MultiplyDragByParticleVelocity = GUI.Toggle(new Rect(25, y, 220, 30), m_MultiplyDragByParticleVelocity, "Multiply Drag by Particle Velocity");
        y += spacing;
    }
}

Properties

Inherited Members