UE5 - Niagara

Sprite Smoke

A prechewed run-through of the sprite smoke tutorial.

Sprite Smoke
- Note:
  This example uses the M_smoke_subUV Material, which can be found with the Starter Content.
- Create the System and Emitter
  - Create a folder, name it “Niagara_fx” (or something else) and step into it.
  - Create a Niagara System, RMB click > FX > Niagara System (or choose from create basic assets at the top of the popup menu)
  - Select New system from selected emitters. Then click Next.
  - Under Template, select Simple Sprite Burst. Click the Plus sign icon (+) to add the emitter to the list of emitters to add to the system. Then click Finish
  - Name the new system “NS_smoke”. Double-click to open it in the Niagara Editor.
  - We can rename the emitter instance by selecting it and pressing F2 (or slow LMB double click) name it “FX_Smoke”
- Change Renderer Settings
  - Setup Material
    - On the emitter node select *Render > Sprite Renderer to open it in the Selection panel
    - Set Material : “M_smoke_subUV” material
    - Set Sub Image Size : 8 (x) and 8 (y)
      - Since we use a Spritesheet / SubUV material we nede to set the num row & colums (u & v)
    - Set Sub UV Blending Enabled : Checked
    - Drag the SmokeSystem into your Level.
      - Note When you make a particle effect, it is always a good idea to drag your system into your Level. This gives you a chance to see every change and edit in context. Any changes you make to the system automatically propagate to the instance of the system in your Level.
- Edit the Emitter Update Group Settings
  - Note First you will edit the modules in the Emitter Update group. These are behaviors that apply to the emitter, and that update each frame
  - Remove Instantaneous module
    - In the System Overview, click the Emitter Update group to open it in the Selection panel.
    - You want to create a constant column of smoke, not a burst of smoke. Click the Trashcan icon to delete the Spawn Burst Instantaneous module.
  - Add Spawn Rate
    - Add the Spawn Rate module to the Emitter Update group.
      - Clicking the + icon (at the top-right of the Emitter update in the selection panel)
      - Start typing “spa…” select Spawn Rate
      - Set the Spawn Rate to 50.
  - Set Infinite loop
    - Note We set the sim to run on an inifinite loop while building the effect. This gives us more time to evaluate how the settings are affecting the effect.
    - In the Emitter State module click the dropdown for Life Cycle Mode and select Self.
    - Click the dropdown for Loop Behavior and select Infinite.
- Particle Spawn Group Settings
  - Note These modules contain behaviors that apply to particles when they first spawn.
  - Life span
    - On the emitter overview select Particle Spwan
    - In the Selection panel expand Particle Spawn > Initialize Particle > Point Attributes
    - If we wanrt some more random life we can set:
      - Lifetime Mode : Random
      - Lifetime Min : 2
      - Lifetime Max : 3
  - Sprite Size
    - Whith the Particle spawn still in the selection panel expand the Sprite Attributes section.
    - Sprite Size Mode : Random Uniform
    - Uniform Sprite Size Min : 75
    - Uniform Sprite Size Max : 200
  - Sprite Rotation
    - In the Sprite attributes section set:
      - Sprite Rotation Mode : Direct Normalized Angle (0-1)
        
        This means the rotation angle is calculated as a number between 0 and 1 instead of degrees
      - Sprite Rotation Angle click on the down arrow on the right side and start typing ‘rand…’ click on Random Range Float (General > Dynamic Inputs > Random Range Float)
        
        Minimum : 0.25
        
        Maximum : 0.5
  - Initial Velocity
    - Click on the + icon on the right side of the Particle Spawn (in the selection panel, tip you can also click on the emitter node in the system overview)
    - In the popup dialog start typing ‘vel…’ select “Add Velocity”
    - Click the dropdown arrow on the right side of the Velocity attributes (the three xyz floats) and start typing ‘rand…’ select Random Range Vector
      - Minimum : X: 0, Y: 0, Z: 50
      - Maximum : X: 1, Y: 1, Z: 200
  - Shape Location
    - This controls the shape & origin where particles are spawned.
    - Add a shape location.
      - Click on the + icon on the right side of the Particle Spawn, start typing “sha…”” select Shape Location
    - Set Properties
      - Shape Primitive : Sphere
      - Sphere Radius : 64
      - Sphere Distribution : Random
  - SubUV Animation
    - Note
      - According to the epic tutorial this was added in the section Particle Spawn. When doing this I did not get the sub uv sampling to work, I guess since the uv coord is sampled once during the spawn and does not update over time. To get this to work I added it to the Particle Update section instead.
      - Since we use a spritesheet, we want to control which section of the spritesheets gets sampled in order to give the illusion of movement.
    - Click on the + icon and start typing “sub…” select Sub UV Animation
    - Set the Range
      - Make sure that the Sub UV Animation Mode is set to linear.
      - Set the Start Frame Range Override to 0
      - Set the End Frame Range Override to 63
        
        We do this since 8 x 8 = 64 frames
    - Set the Sprite Renderer
      - This was not set in the tutorial, but in order to not get any warnings I needed to do the ollowing.
      - In the tab Sub UV Animation > Spritre Renderer > source > Sprite Renderer I needed to set which sprite renderer to use. I set this to the same renderer we used under the tab Render. Note that it is possible to rename the renderer.
- Particle Update Group Settings
  - Here we add modules that apply behaviors to particles, and update each frame.
  - Note that I added the Sub UV Animation module here instead of the Particle Spawn
  - We can add curl noise, drag, acceleration and so on
- Note
  - If you want to be able to reuse the smoke emitter in your system, you can save it as a separate asset. Click the Gear icon to open the Emitter Settings menu, and select Create Assset From This. The result is an independent Niagara Emitter asset.
  - Sprite Smoke epic tutorial

Sequencer

Custom Parameter

Here is a way to add a user parameter that you can animate in sequencer

Add user parameter
- Open up the niagara system
- Click the User Parameters tab on the left side of UI
- Lets add a float parameter
  - Click the plus icon on the right side of the User Parameters UI
  - Make New > Common > Float
  - Give it a descriptive name, like Particle Amount
  - Note that you can delete parmeters by RMB clicking them in the User Parameters panel > delete
Connect the parameter to emitter
- Lets connect the user parm to the spawn rate of the emitter
- Select the Spawn Rate module of the Emitter Update section.
  - If you do not have one add it
- In the selection Panel, click on the down arrow on the right side of the spwan rate parameter
  - Start typing “Part…” select Particle Amount (Link Inputs > User > Particle Amount)
Animate parm in sequencer
- Drag and drop NS (niagara system) to the viewport
- Create a level Sequence
- Add the niagara system to the sequencer
- Add Niagara Component track
  - Click the + icon to the right on the NS track Components > NiagaraComponent0
- Add a Niagara System Life Cycle Track
  - Click the + icon to the right on the Niagara Component track Tracks > Niagara System Life Cycle Track
- Add the User Parameter
  - Click the + icon to the right on the Niagara Component track Tracks > Particle Amount Parameter Track

Cache

Niagara Cache Track
- Add the niagara Cach plugin
- Add Niagara Cach Track
  - Click the + icon to the right on the Niagara Component track Tracks > Niagara Cache
  - Note that the life cycle track needs to start on the same frame (or earlier) than the cahce track
- Click on the red dot to cahce
- Note
  - I needed to remove the Cache berfore rendering with the MRQ, if I did not do this I got really weird results.