xpGroup

A particle can be assigned to a group.

To use different particle groups in an emitter, drag the groups you want to use into the Groups to Use list in the xpEmitter.

Alternatively, you can click the Create and Add Group button in the emitter Groups tab; this will create a group and automatically add it to the Groups to Use list.

If no groups are present in the list, all particles will be in the default group and will have the color and shape found in the emitter.

If more than one group is in the list, new particles will be assigned randomly or sequentially to one of the groups, depending on the emitter setting.

Note: More than one emitter can use the same group if you wish.

You can add as many groups to a scene as you wish but the group must be created before you can assign a particle to it.

To create a group, add an xpGroup object to the scene.

This can be done using the main plugin menu, or the system object, or in the Groups tab in the xpEmitter.

A group is not specific to a single emitter; you can have multiple emitters all emitting particles in the same group, if you wish.

This is a field which shows you the internal number of this group.

This number is normally added when the group is created, but can also be edited by the user, if desired.

Most of the time it is recommended that you don't do this, but in some circumstances, such as merging two scenes, you may have two or more groups with the same number.

This number is used to identify to a particle which group it is in; if you have two groups with the same number the particle will assume it belongs to the first group it finds with that number.

If you do change it, the actual number isn't important as long as it isn't shared by any other group.

Groups can control many aspects of an emitted particle.

Exactly which parameters are taken from the group, and which from the emitter, are determined by this drop-down.

Set as Standard, by default, the alternative options are: Display Only and Extended.

In this mode, the group object controls the display settings and emission settings.

Physical properties are taken from the emitter which emits the group.

Only the display settings are taken from the group object.

Emission settings and physical properties are taken from the emitter which emits the group.

Display and emission settings and physical properties, are taken from the group.

The emitter has no effect on any of these parameters.

Set as Squares, by default, this is the same setting as found in the xpEmitter's Display tab.

Note: This and the Color setting make it possible for each group to have its own unique appearance (which does not depend on the group number being unique) without having to use Question and Action objects to accomplish that.

It is not possible to specify the size and transparency of spheres or circles for group objects so, if you choose Spheres or Circle (Filled) as the display type, the size and transparency are taken from whichever emitter(s) emit particles in this group.

Set as Single Color, by default, these are the same as in the xpEmitter Display tab.

The particles all have the same color, from the Color setting.

Particles are assigned a randomly-chosen color.

A random color is chosen for each particle from the Gradient Color gradient.

The particle color is chosen from the Gradient Color gradient but the color chosen is determined by the Gradient Parameter drop-down.

In this mode, particles are colored by a shader placed into the Shader link.

The color of the particle in the viewport.

This is used in the editor and in the X-Particles material if that is set to use the particle color.

The default is a light green, as in the xpEmitter.

Note: If you change this setting, the color of the xpGroup icon in the object manager will also change to the same color.

If Color Mode is set to Use Shader there is the option to use a shader to generate the color.

This is the link field for the shader to use.

Set as Shader Space, by default, this menu determines how the shader is sampled.

The alterative option is Random.

This will sample the color at the particle position in the 3D world.

This will sample the shader at a different random point in each frame.

This is used in Gradient (Random) and Gradient (Parameter) modes.

By default, this is a blue to white gradient.

Set as Age, by default, in Gradient (Parameter) mode the color the particles are given is taken from the Gradient Color but the precise color is determined by the chosen setting in this drop-down.

The other options are: Speed, Speed (World), Radius, Fluid Density, Fluid Density/Velocity, Granular, Fluid Surface, Mass, Temperature, Smoke, Fire, Fuel, Distance Traveled, Direction, P-P Distance and Rotation.

When this box is checked, the color gradient is automatically mapped to the range of values in that property.

For example, if Speed is chosen in Gradient Parameter, the slowest particles are given the color at the left edge of the gradient, while the fastest ones are given the color at the right edge.

If this setting is unchecked, you can choose the range to map to the gradients using the Min and Max settings.

The minimum and maximum values to use when the Auto setting is unchecked.

Set as Heading, by default, this is used only if Gradient Parameter is set to Direction or Rotation.

The options in the menu are the individual axes Heading. Pitch or Bank or HPB Combined (all three axes combined).

These are identical to the parameters of the same names in the xpEmitter, Emission tab.

They are only available in Standard and Extended modes.

The particle’s initial speed in screen units per second.

The particle radius, in scene units.

The particle scale.

If these boxes are checked, the value in each of the Scale and/or Scale Var fields are changed uniformly - that is, a change in one vector component is made in the other two components.

This is a convenience feature to save having to change all three components to match.

If you need to set the components to different values, uncheck either or both boxes.

These parameters are identical to the parameters of the same names in the xpEmitter, Extended Data tab.

They are only available in Extended mode.

The particle's mass.

These are not real-world values (i.e. a value of '1' must not be taken to mean 1 gram, or 1 pound, etc.).

You can add variation to the mass with the Variation setting.

If you enable this setting, the mass of the particle is linked to its radius, so that larger particles have greater mass.

In X-Particles, both mass and radius can be set but if either have any variation included, it is not the case that the largest particles have the greatest mass.

That is what this setting does; it maps the mass to the radius.

These parameters are used to give additional control over friction and bounce on collision.

They are inherent particle parameters which interact with the friction and bounce settings in other X-Particles objects.

If you have set the particle Bounce to 100% the amount of bounce will be completely controlled by the other object - for example, the xpCollider tag.

This is the default setting.

If you reduce it, then the amount of bounce will be reduced and if it is set to 0 (zero), there will be no bounce at all, no matter what the setting is in any other object.

With friction, both the particle and the surface must have friction greater than 0 (zero) for any friction effect to occur.

These values are all used in the xpExplosiaFX object, when generating fire and smoke.

This is a value you can set to anything you like.

It can be changed with the Physical modifier or Xpresso, but X-Particles itself will not change it during the course of any simulation.