Particle Flow provides three operators for applying materials to particles. To give the same appearance to all particles throughout an event, use Material Static Operator. If you're using a compound material such as Multi/Sub-Object, you can assign different sub-materials to different particles with the Material Frequency operator. And to assign materials that change in appearance over time, use the Material Dynamic operator.
Related to this is the Mapping operator, which lets you give the same mapping coordinates to the entire surface of each particle in an event, thus using a single pixel from a material to color the particles. By animating the mapping coordinates, you can cause the particles to change color over time. This is particularly effective with a gradient material.
The Bitmap map, used in conjunction with Material Dynamic, lets you assign different frames from an image sequence to particles based on the particle age, among other effects.
Following are some items to keep in mind when using materials with Particle Flow:
- A material is a static property of an event. It does not travel along with the particles from one event to the next. A particle's material ID does, but its material does not. If you want particles always to use the same material, define the material in the global event with a Material operator or a Shape Instance operator. Otherwise, you need to define it in each local event.
- The primitive particle shapes available with the Shape operator do not have mapping coordinates. The Mapping operator applies the same mapping coordinates to each particle's entire surface, so it's not suitable in this situation. If you want to apply image-based materials to particles, use Shape Instance instead.
- If you use a Material operator with Shape Instance, be sure to apply mapping coordinates to the reference object(s). You can do this by making sure the object's Generate Mapping Coords option is on (if available), or applying a UVW Map modifier or Unwrap UVW modifier. If you don't apply mapping coordinates, the system generates a Missing Map Coordinates warning when you render the scene.
- If you use an object with a material already applied as a reference object for instanced particles, you don't need a Material operator in the same event. However, the material appears only in the event containing the Shape Instance operator; it does not persist from event to event.
- If you use the Cache operator with Update set to Always, toggling the Material Editor
Show Map In Viewport switch causes Particle Flow to recalculate the cache. - You can drag a material from the Material Editor to a Particle Flow source icon, but the material will not have any effect on the system. You must use a Material operator or Shape Instance to apply materials to particles in Particle Flow.
- Once you've assigned a material to a Material operator, the material shows up in the Material Editor as “hot”; that is, triangles appear in the corners of its sample slot. However, because of the nature of the Particle Flow data structure, the Material Editor functions Select By Material and Get Material Browse From Selected do not work correctly with Particle Flow systems. You can, however, use Get Material Browse From Scene.