Unity Cookbook. Particle system

Particle system

Two ways to create a particle system

Built-in particle system

Particle system component in Inspector

Particle system modules

  • Shape
    • Shape of the particle emitter
    • Shape (Circle is good for 2D)
    • Radius
    • Arc
    • Position, Rotation
  • Color over lifetime
    • You can add a gradient so the particles change color over time
    • With the handles on top of the gradient, you can also change alpha value (opacity)
  • There’s also modules for changing other properties over lifetime
  • Texture Sheet Animation
    • If you want your particles to have a sprite animation, use this
    • Grid: tell how many cels your sprite sheet has
  • Renderer
    • Material
      • You need to create a new material for your particles (see next slide!)
    • Sorting fudge: Bigger numbers mean particles are more probably in front of ofter GameObjects. Yeah.
    • Order in layer: Tells the draw order of particles in accordance to 2D layers, like tilemaps.

Particle material

  • Create a new material file with Create > Material
  • Set some settings for it.
    • For basic sprite particles:
      • Shader: Particles/Standard Unlit
      • Rendering Mode: Fade or Cutout
      • Drag your particle sprite (or sprite sheet for animated particles!) to Albedo

Control particle system with code

  • How to stop / start emitting particles: 
      public ParticleSystem particles;

  if (!particles.isEmitting && Input.GetButtonDown("Fire1"))
  {
      particles.Play();
  }
  if (particles.isEmitting && Input.GetButtonDown("Fire1"))
  {
      particles.Stop();
  }
  • To emit 20 particles on command: 
      if (particles.isPlaying && Input.GetButtonDown("Fire2"))
  {
      particles.Emit(20);
  }

Change properties with code

  • You can’t change module properties directly like this: 
    dustParticles.shape.rotation = somethingNew
  • You have to assign a new variable for the module first, and change the variables there: 
      var shape = dustParticles.shape;
  shape.rotation = new Vector3 (
      0, 0, Mathf.Atan2(PlayerMove.y, PlayerMove.x) * Mathf.Rad2Deg
  );
  var main = dustParticles.main;
  main.startSpeed = 2 * PlayerMove.magnitude;

Collision modules

  • Collision
    • Type: World
    • Mode: 2D / 3D
    • Lifetime loss: 1 (Die on collision)
    • Collider Force (Bounce on collision)
    • Collide with: You can change the collision layers so the particles only collide with specific layers.
      • (GameObject’s Collision layer does not affect particles!!)
  • To run a script on particle collision:
    • Send Collision Messages has to be checked
    • add callback function OnParticleCollision() (works also in 2D, there is no OnParticleCollision2D)
  • Triggers
    • allows you to access and modify particles based on their interaction with specific colliders
    • Add colliders to the List under the Triggers module
    • Set Inside, Outside, Enter and Exit to preferred value
      • Ignore: does nothing
      • Kill: destroys particle
      • Callback: calls the OnParticleTrigger() callback on attached scripts (again, there is no OnParticleTrigger2D)

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