Particle Systems

Manually keyframing ten falling snowflakes is possible. Keyframing ten thousand falling snowflakes is impossible. For simulating massive crowds of autonomous objects (snow, rain, sparks, dust motes, swarms of bees), Oraphim provides a dedicated Particle System.

The Particle engine in Oraphim operates in a true 3D environment and relies on a specific sequence of nodes to function.

The Core Particle Nodes

Every particle system requires at least three nodes in a very specific order:

  1. pEmitter: Generates the particles. It defines where they spawn, how many spawn per frame, their velocity, their lifespan, and what they look like (their style).
  2. pRender: Particles are just mathematical points in 3D space. The pRender node converts that 3D mathematical data back into 2D visible pixels so they can be merged over your background.
  3. Merge: You must pipe the output of the pRender node into a standard Merge node to place the particles over your footage.

Building a Basic Snow System

  1. Open the Compositor on an empty sequence or a clip.
  2. Press Shift + Spacebar and add a pEmitter node.
  3. Connect the output of pEmitter1 to a new pRender node.
  4. Connect the output of pRender1 to a Merge node (with your background footage in the Yellow input).
  5. If you play your timeline, you will see generic white dots spawning in the center of the screen.

Configuring the Emitter

Select the pEmitter node and open the Inspector to customize the system:

  • Controls Tab > Number: Increase this to spawn more particles per frame.
  • Controls Tab > Lifespan: How many frames a particle exists before disappearing.
  • Region Tab > Region: Change this from "Sphere" to "Rectangle", and expand the Width and Height to cover the entire top edge of your screen. Now the snow will spawn across the whole sky.
  • Style Tab > Style: Change this from "Point" to "Blob" or "Bitmap". If you select "Bitmap", a new input arrow will appear on the pEmitter node, allowing you to pipe in a custom image (like a picture of a snowflake or a leaf) that the system will multiply.

Adding Physical Forces

Particles are boring if they just travel in a straight line. You can add "Forces" between the pEmitter and the pRender to simulate physics.

  • Add a pDirectionalForce node between them and set the force to pull down (-Y) to simulate gravity.
  • Add a pTurbulence node to make the falling snow swirl and dance chaotically in the wind.
  • Add a pBounce node, set the region to a flat plane at the bottom of the screen, and the snowflakes will physically bounce off the floor.