Cinema - Maxwell Particles Tag

The Maxwell Particles tag determines how Cinema Particle Emitter and Particle Geometry objects are exported. Depending how options are set, they result in the creation of a MaxwellParticles Extension object, or a mesh with a MaxwellCloner (modifier) Extension.

Particle Emitter objects will only be exported using this tag if they do not contain geometry; otherwise, they will be exported the same as in previous versions of the plugin. Particle Geometry objects are not specifically considered in the export, unless they have (or inherit) a Maxwell Particles tag, meaning that they may also produce real geometry, depending on how the particles are set up; addition of a Particles tag will not prevent export of this geometry.

Export of particles can be disabled temporarily using this switch (a Maxwell Particles tag must be present for particles to be rendered at all).

Geometry

Parameters in this section determine the nature of each exported particle.

Particle Radius

By default, Cinema particles are exported as analytical spheres using the MaxwellParticles Extension. For Particle Emitters, exported spheres are one export unit in radius, modulated by the object's End Scale and Scale Variation values, with the tag's Particle Radius value being used to scale the particle cloud globally (this uses the MaxwellParticles Radius Factor parameter). For Particle Geometry objects, the size of each sphere is determined by the Size value of each individual particle (the Size parameter in PStorm, for example), where 1.0 means 1.0 export unit. The entire group will then be scaled using the Particle Radius value.

Clone Object & Use Clone

If a Polygon Object has been specified in the Clone Object link, and Use Clone has been checked, particles will be exported as clones of that polygon object, using the MaxwellCloner Extension, rather than as spheres. When this is the case, some other parameters in the tag (Particle Radius, Particle Age, and Particle Mass) will have no effect, since they relate only to MaxwellParticles export.

Scale Factor

This value will be used to scale the geometry specified in the Clone Object link.

Scale with radius

If this is enabled, each clone will also be scaled according to information contained in its Cinema particle data. For Particle Emitters, the radius does not change, but for Particle Geometries, it is also necessary to make sure that the Particle Radius array is exported.

Align to velocity

If this is checked, each clone will be oriented such that its Y axis aligns with its particle's velocity vector.

Motion Blur

These parameters simply enable and scale motion blur for the exported particles. The initial amount of blur depends on the velocity of each particle, and on the shutter speed of the camera.

Array Loading

Several different arrays of data may be involved in rendering particles. Since it is desirable to keep memory usage to a minimum, the following options are provided, for the purpose of loading the various arrays of data selectively. Several of the arrays also have a related Channel ID; if during export, an array is enabled, then custom UVs will be generated for the particle cloud, on the specified texture channel.

Particle Radius

Since Particle Emitters do not output particles of differing size, this option will have no effect on them. Particle Geometries may export differing particle size, though, so if you want this information to be reflected in the export, be sure to enable this option. When exporting clones, be aware that the Scale with radius option will have no effect, unless Particle Radius loading is enabled.

Particle ID

Each particle can have a unique (integer) identifier. This is used to establish coherency of particles between frames, so it is important for things like Object ID color, and for the creation of extra particles (i.e. the export of Extra Particles per Particle). In the case of Particle Geometries, this ID is assigned by the Thinking Particles system. No such ID is provided by a Particle Emitter, so in that case, the particle's index in its array is used as an ID.

Particle Age & Mass

When exporting a Particle Geometry object, per-particle Age and Mass values may be generated by Thinking Particles. Enabling these options will cause these values to be written into the particle cloud.

Extra Particles per Particle

The Maxwell particles system can optionally generate extra particles for each particle defined in Cinema. The Quantity value simply specifies how many extra particles to generate. The Dispersion and Deformation parameters control how the cloud of extra particles is generated. Dispersion sets the size of the cloud of extra particles, around each exported particle. Deformation sets the amount of deformation of the new particles cloud along the speed vector of the original particle. Note that in order to achieve good results, the Particle ID array needs to be exported when using this feature.