Particle Collisions

Checked with version: 5.5

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Difficulty: Intermediate

In this live training session you will learn how to control particle systems at runtime via script, how to use collision messages from particles to drive gameplay and how to render decal style effects using particles.

Particle Collisions

Intermediate Scripting

Download the assets used in this training here

ParticleLauncher

Code snippet

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

public class ParticleLauncher : MonoBehaviour {

    public ParticleSystem particleLauncher;
    public ParticleSystem splatterParticles;
    public Gradient particleColorGradient;
    public ParticleDecalPool splatDecalPool;

    List<ParticleCollisionEvent> collisionEvents;

    void Start () 
    {
        collisionEvents = new List<ParticleCollisionEvent> ();
    }

    void OnParticleCollision(GameObject other)
    {
        ParticlePhysicsExtensions.GetCollisionEvents (particleLauncher, other, collisionEvents);

        for (int i = 0; i < collisionEvents.Count; i++) 
        {
            splatDecalPool.ParticleHit (collisionEvents [i], particleColorGradient);
            EmitAtLocation (collisionEvents[i]);
        }

    }

    void EmitAtLocation(ParticleCollisionEvent particleCollisionEvent)
    {
        splatterParticles.transform.position = particleCollisionEvent.intersection;
        splatterParticles.transform.rotation = Quaternion.LookRotation (particleCollisionEvent.normal);
        ParticleSystem.MainModule psMain = splatterParticles.main;
        psMain.startColor = particleColorGradient.Evaluate (Random.Range (0f, 1f));

        splatterParticles.Emit (1);
    }
        
    void Update () 
    {
        if (Input.GetButton ("Fire1")) 
        {
            ParticleSystem.MainModule psMain = particleLauncher.main;
            psMain.startColor = particleColorGradient.Evaluate (Random.Range (0f, 1f));
            particleLauncher.Emit (1);
        }

    }
}

ParticleDecalData

Code snippet

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

public class ParticleDecalData 
{
    public Vector3 position;
    public float size;
    public Vector3 rotation;
    public Color color;

}

ParticleDecalPool

Code snippet

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

public class ParticleDecalPool : MonoBehaviour {

    public int maxDecals = 100;
    public float decalSizeMin = .5f;
    public float decalSizeMax = 1.5f;

    private ParticleSystem decalParticleSystem;
    private int particleDecalDataIndex;
    private ParticleDecalData[] particleData;
    private ParticleSystem.Particle[] particles;

    void Start () 
    {
        decalParticleSystem = GetComponent<ParticleSystem> ();
        particles = new ParticleSystem.Particle[maxDecals];
        particleData = new ParticleDecalData[maxDecals];
        for (int i = 0; i < maxDecals; i++) 
        {
            particleData [i] = new ParticleDecalData ();    
        }
    }

    public void ParticleHit(ParticleCollisionEvent particleCollisionEvent, Gradient colorGradient)
    {
        SetParticleData (particleCollisionEvent, colorGradient);
        DisplayParticles ();
    }

    void SetParticleData(ParticleCollisionEvent particleCollisionEvent, Gradient colorGradient)
    {
        if (particleDecalDataIndex >= maxDecals) 
        {
            particleDecalDataIndex = 0;
        }
            
        particleData [particleDecalDataIndex].position = particleCollisionEvent.intersection;
        Vector3 particleRotationEuler = Quaternion.LookRotation (particleCollisionEvent.normal).eulerAngles;
        particleRotationEuler.z = Random.Range (0, 360);
        particleData [particleDecalDataIndex].rotation = particleRotationEuler;
        particleData [particleDecalDataIndex].size = Random.Range (decalSizeMin, decalSizeMax);
        particleData [particleDecalDataIndex].color = colorGradient.Evaluate (Random.Range (0f, 1f));

        particleDecalDataIndex++;
    }

    void DisplayParticles()
    {
        for (int i = 0; i < particleData.Length; i++) 
        {
            particles [i].position = particleData [i].position;
            particles [i].rotation3D = particleData [i].rotation;
            particles [i].startSize = particleData [i].size;
            particles [i].startColor = particleData [i].color;
        }

        decalParticleSystem.SetParticles (particles, particles.Length);
    }
}

SplatOnCollision

Code snippet

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

public class SplatOnCollision : MonoBehaviour {

    public ParticleSystem particleLauncher;
    public Gradient particleColorGradient;
    public ParticleDecalPool dropletDecalPool;

    List<ParticleCollisionEvent> collisionEvents;


    void Start () 
    {
        collisionEvents = new List<ParticleCollisionEvent> ();
    }

    void OnParticleCollision(GameObject other)
    {
        int numCollisionEvents = ParticlePhysicsExtensions.GetCollisionEvents (particleLauncher, other, collisionEvents);

        int i = 0;
        while (i < numCollisionEvents) 
        {
            dropletDecalPool.ParticleHit(collisionEvents[i], particleColorGradient);
            i++;
        }

    }

}

Scripting

  1. Scripts as Behaviour Components
  2. Variables and Functions
  3. Conventions and Syntax
  4. C# vs JS syntax
  5. IF Statements
  6. Loops
  7. Scope and Access Modifiers
  8. Awake and Start
  9. Update and FixedUpdate
  10. Vector Maths
  11. Enabling and Disabling Components
  12. Activating GameObjects
  13. Translate and Rotate
  14. Look At
  15. Linear Interpolation
  16. Destroy
  17. GetButton and GetKey
  18. GetAxis
  19. OnMouseDown
  20. GetComponent
  21. Delta Time
  22. Data Types
  23. Classes
  24. Instantiate
  25. Arrays
  26. Invoke
  27. Enumerations
  28. Switch Statements
  1. Properties
  2. Ternary Operator
  3. Statics
  4. Method Overloading
  5. Generics
  6. Inheritance
  7. Polymorphism
  8. Member Hiding
  9. Overriding
  10. Interfaces
  11. Extension Methods
  12. Namespaces
  13. Lists and Dictionaries
  14. Coroutines
  15. Quaternions
  16. Delegates
  17. Attributes
  18. Events
  1. Building a Custom Inspector
  2. The DrawDefaultInspector Function
  3. Adding Buttons to a Custom Inspector
  1. MonoDevelop's Debugger
  2. Good Coding Practices in Unity
  3. Unity Editor Extensions – Menu Items
  4. Creating Meshes
  1. AssetBundles and the AssetBundle Manager
  2. Mastering Unity Project Folder Structure - Version Control Systems
  1. Installing Tools for Unity Development
  2. Building your first Unity Game with Visual Studio
  3. Editing Unity games in Visual Studio
  4. Debugging Unity games in Visual Studio
  5. Graphics debugging Unity games in Visual Studio
  6. Taking Unity games to Universal Windows Platform
  7. Testing Unity games on Android in Visual Studio
  1. Scripting Primer and Q&A
  2. Scripting Primer and Q&A - Continued
  3. Scripting Primer and Q&A - Continued (Again)
  4. Persistence - Saving and Loading Data
  5. Object Pooling
  6. Introduction to Scriptable Objects
  7. How to communicate between Scripts and GameObjects
  8. Coding in Unity for the Absolute Beginner
  9. Sound Effects & Scripting
  10. Editor Scripting Intro
  11. Writing Plugins
  12. Property Drawers & Custom Inspectors
  13. Events: Creating a simple messaging system
  14. Ability System with Scriptable Objects
  15. Character Select System with Scriptable Objects
  1. Intro and Setup
  2. Data Classes
  3. Menu Screen
  4. Game UI
  5. Answer Button
  6. Displaying Questions
  7. Click To Answer
  8. Ending The Game and Q&A
  1. Intro To Part Two
  2. High Score with PlayerPrefs
  3. Serialization and Game Data
  4. Loading Game Data via JSON
  5. Loading and Saving via Editor Script
  6. Game Data Editor GUI
  7. Question and Answer
  1. Overview and Goals
  2. Localization Data
  3. Dictionary, JSON and Streaming Assets
  4. Localization Manager
  5. Startup Manager
  6. Localized Text Component
  7. Localized Text Editor Script
  8. Localization Q&A
  1. Introduction and Session Goals
  2. Particle Launcher
  3. Particle Collisions
  4. ParticleLauncher Script
  5. Particle Collisions and Scripting
  6. Random Particle Colors
  7. Drawing Decals with Particles
  8. Collecting Particle Information For Display
  9. Displaying Particles Via Script
  10. Droplet Decals
  11. Questions and Answers