nParticleShape

Particle Size

Radius: Determines the overall radius of the nParticle object. The Radius setting provides the input value for the Radius Scale ramp.

Radius Scale

The Radius Scale ramp sets per particle radius scale values which are applied to the Radius attribute to compute per particle radius values. The vertical component represents the Radius Scale values from 0 (no radius) to 1 (equal to the Radius attribute value). See Working with nParticle attribute ramps.

If the Radius Scale Input is set to Off, the per particle attributes are deleted. If it is set to any other value, the radius per particle attributes are created if they don’t already exist.

Selected Position: This value indicates the position of the selected Radius Scale value on the ramp (between 0 on the left to 1 on the right).
Selected Value: This value indicates particle radius on the ramp at the selected position.

Interpolation

Controls the way nParticle radius blend between each position on the ramp. The default setting is Linear.

None: The Radius Scale curve is flat between points.
Linear: Radius Scale values are interpolated with a linear curve.
Smooth: Radius Scale values are interpolated along a bell curve, so that each value on the ramp dominates the region around it, then blends quickly to the next radius value.
Spline: Radius Scale values are interpolated with a spline curve, taking neighboring indices into account for greater smoothness.

Radius Scale Input

Specifies which attribute is used to map the radius ramp values.

Off: When off, the per particle radius attributes are deleted. If you want to use an expression with radius, you need to manually add the radius per particle attributes again. See Set attributes on a per particle basis.
Age: Per particle radius is determined by the nParticle’s age, which is based on the particle Lifespan mode. See Lifespan Attributes.
Normalized Age: Per particle radius is determined by the normalized age of the nParticle. To use Normalized Age, the nParticle object must have a defined lifespan. For example, the nParticle object’s Lifespan Mode attribute must be set to Constant or Random range. See Lifespan Mode.

When Normalized Age is used, per particle radius is mapped within the range of the nParticle object’s lifespan.
Speed: Per particle radius is determined by nParticle speed.
Acceleration: Per particle radius is determined by nParticle acceleration.
Particle ID: Per particle radius is determined by the nParticle’s ID. Particle IDs are unique and generated at the beginning of the particle’s lifespan.
Randomizing ID: Per particle radius is determined by a randomized nParticle ID.

Input Max: Sets the maximum value for the range used by the Radius Scale ramp.

Radius Scale Randomize: Sets a random multiplier for the per particle radius scale values.

Collisions

Collide: When on, the current nParticle object collides with passive objects, nCloth objects, and other nParticle objects that share the same Maya Nucleus solver. When off, the current nParticle object does not collide with passive objects, nCloth objects, or other nParticle objects that share the same Maya Nucleus solver.
Self Collide: When on, particles generated by the nParticle object collide with each other. When off, these particles do not collide with each other.
Collision Layer: Assigns the current nParticle object to a specific collision layer. Collision Layers determine how nParticle, nCloth, and passive objects that share the same Maya Nucleus solver interact.

nParticle objects on the same collision layer collide normally. However, when nParticle objects are on different layers, particles on lower value layers will have priority over particles on higher value layers. So an nParticle object on collision layer 0.0 will push an nCloth object or another nParticle object on collision layer 1.0, which in turn will push an nCloth object or another nParticle object on collision layer 2.0. This collision priority occurs in the range set by the Collision Layer Range attribute on the nucleus node.

NotenCloth and Passive objects in collision layers only collide with nParticle objects that are in the same collision layer, or in layers of higher value.

See Collision Layer in the nClothShape node description.
Collide Width Scale: Specifies a collision scale value for collisions between the current nParticle object and other nucleus objects.
Self Collide Width Scale: Specifies a self-collision scale value for the current nParticle object. Self Collide Width Scale allows you to scale the thickness of collisions that occur between particles emitted from the same nParticle object. Setting Self Collide Width Scale improves the smoothness of particle emission of self colliding particles, and speeds up the simulation. Self Collide Width Scale is 1.0 by default.

Solver Display

Specifies what Maya Nucleus solver information is displayed in the scene view for the current nParticle object. Solver Display can help you better diagnose and troubleshoot any problems you may be having with your nParticles.

Off: No Maya Nucleus solver information is displayed in the scene view.
Collision Thickness: When on, the collision volumes for the current nParticle object are displayed in the scene view. Collision Thickness helps you visualize the thickness of colliding nParticles and it is useful when tweaking nParticle collisions with other nParticle objects or nCloth and passive objects.
Self Collision Thickness: When on, the self-collision volumes for the current nParticle object are displayed in the scene view. Self Collision Thickness helps you visualize nParticle self-collision thickness and it is useful when tweaking nParticle self-collisions (collisions between particles emitted from the same nParticle object).

Display Color: Specifies the color of the collision volumes for the current nParticle object. Display Color is only visible when your scene view display mode is set to Shading > Smooth Shade Selected Items or Shading > Flat Shade Selected Items.
Bounce: Specifies the springiness or bounciness of the current nParticle object. Bounce determines the amount of the nParticle’s deflection or rebound on collision with itself, passive objects, nCloth or other nParticles objects that share the same Maya Nucleus solver.

The amount of Bounce an nParticle object should have is determined by the type of nParticle effect. For example, nParticles with a Bounce of 0.0 would not be bouncy (such as steel) and an nParticle with a Bounce of 0.9 would be very bouncy (such as rubber). Bounce is 0.0 by default.

NoteBounce values greater than 1.0 can cause instability and should be avoided.
Friction: Specifies the amount of friction for the current nParticle object. Friction determines how much nParticles resists relative motion on collision with itself, passive objects, nCloth, and other nParticle objects that share the same Maya Nucleus solver.

The amount of Friction an nParticle object should have is determined by the type of nParticle effect. The affect of Friction is influenced by the nParticle object’s Stickiness value. See Stickiness.
Stickiness: Stickiness specifies the tendency of nParticles to stick to other Nucleus objects when nCloth, nParticle, and passive objects collide.

Stickiness and Friction are similar attributes in that Stickiness is an adhesion force in the normal direction, while Friction is a force acting in the tangent direction. As with Friction, the Stickiness value used in a collision is the sum of the two colliding objects. So, for full sticking, the Friction and Stickiness on the colliding objects should be 1.0. Note that if Stickiness and Friction are both set to 2 on an object, this object will stick to other Nucleus objects that have Stickiness set to 0.

For particles from the same nParticle object to stick to each other, Self Collide must be turned on.
Max Self Collide Iterations: Specifies the maximum number of iterations per simulation step for the current nParticle object's dynamic self collisions. Max Self Collide Iterations clamps the number of iterations to prevent high level property values or a large number of steps from locking up the nParticle object.

Dynamic Properties

Forces In World: See Forces In World.
Ignore Solver Gravity: When on, solver Gravity is disabled for the current nParticle object.
Ignore Solver Wind: When on, solver Wind is disabled for the current nParticle object.
Dynamics Weight: See Dynamics Weight.
Conserve: See Conserve.
Drag: Specifies the amount of drag applied to the current nParticle object. Drag is the component of aerodynamic force parallel to the relative wind which causes resistance. Drag is 0.05 by default.
Damp: Specifies the amount the motion of the current nParticles are damped. Damping progressively diminishes the movement and oscillation of nParticles by dissipating energy.
Mass: Specifies the base mass of the current nParticle object. Mass determines the density or the weight of an nParticle object when its Maya Nucleus solver’s Gravity is greater than 0.0.

The Mass an nParticle should have is determined by the type of nParticle effect you want to achieve.

Mass affects behavior in collisions and behavior with Drag. nParticles with high Mass have greater influence on other nParticle or nCloth objects with low Mass, and they are less influenced by Drag.

Mass Scale

The Mass Scale ramp sets per particle mass scale values which are applied to the Mass attribute to compute per particle mass values. The vertical component represents the Mass Scale values from 0 (no mass) to 1 (equal to the Mass attribute value). See Working with nParticle attribute ramps.

Selected Position: This value indicates the position of the selected Mass Scale value on the ramp (between 0 on the left to 1 on the right).
Selected Value: This value indicates nParticle mass on the ramp at the selected position.

Interpolation

Controls the way particle mass blends between each position on the ramp. The default setting is Linear.

None: The Mass Scale curve is flat between points.
Linear: Mass Scale values are interpolated with a linear curve.
Smooth: Mass Scale values are interpolated along a bell curve, so that each value on the ramp dominates the region around it, then blends quickly to the next mass value.
Spline: Mass Scale values are interpolated with a spline curve, taking neighboring indices into account for greater smoothness.

Mass Scale Input

Specifies which attribute is used to map Mass Scale ramp values.

Off: When off, the per particle mass attributes are deleted.
Age: Per particle mass is determined by the particle age, which is based on the particle Lifespan mode. See Lifespan Attributes.
Normalized Age: Per particle mass is determined by the normalized age of the nParticle. To use Normalized Age, the nParticle object must have a defined lifespan. For example, the nParticle object’s Lifespan Mode attribute must be set to Constant or Random range. See Lifespan Mode.

When Normalized Age is used, per particle mass is mapped within the range of the nParticle object’s lifespan.
Speed: Per particle mass is determined by nParticle speed.
Acceleration: Per particle mass is determined by nParticle acceleration.
Particle ID: Per particle mass is determined by the nParticle’s index.
Randomizing ID: Per particle mass is determined by a randomized nParticle ID.
Radius: Per particle mass is determined by the nParticle’s radius.

Max Input: Sets the maximum value for the range used by the Mass Scale ramp.
Mass Scale Randomize: Sets a random multiplier for the per particle mass scale values.

Force Field Generation

Generates a force field that can push (positive fields) nCloth objects and other nParticle objects away from the current nParticles, and pull (negative fields) nCloth objects and other nParticle objects toward the current nParticles. A Point Force Field can only be exerted on Nucleus objects that are assigned to the same Nucleus solver as the nParticle object generating the Point Force Field.

See Force Field Generation.

Point Force Field

Sets the orientation of the Point Force Field.

Off: When turned off, the Point Force Field is not enabled.
World space: Point Force Field is set relative to world space.
Thickness Relative: Point Force Field is relative to the radius of individual nParticles. nParticles with higher Radius values generate stronger Point Force Fields relative to nParticles with low Radius values.

See Radius.

Point Field Magnitude: Sets the strength of the Point Force Field. Positive Point Field Magnitude values push nCloth objects and other nParticle objects away from the current nParticles. Negative Point Field Magnitude values pull nCloth objects and other nParticle objects toward the current nParticles.
Self Attract: Sets the strength of self attractive forces between the points (individual particles) of an nParticle object. Positive Self Attract values pull the points (individual particles) of an nParticle object together. Negative Self Attract values push the points (individual particles) away from each other.
Point Field Distance: Sets the distance (in field units) from the radius of the force generating nParticle that the Point Force Field is active. Outside the Point Field Distance, the Point Force Field does not affect nCloth objects and other nParticle objects.

Point Field Scale

Sets a Point Field Scale ramp that can be used to vary Point Field Magnitude along the Point Field Distance. See Working with nParticle attribute ramps.

Selected Position: This value indicates the position of the Point Field Magnitude on the ramp. The left position on ramp represents Point Field Magnitude at the outside radius of the nParticles. The right position on the curve represents Point Field Magnitude at the edge of the Point Field Distance.
Selected Value: This value indicates Point Field Magnitude at the selected position.

Interpolation

Controls the way Point Field Magnitude blends between each position on the ramp. The default setting is Linear.

None: The Point Field Scale curve is flat between points.
Linear: Point Field Magnitude values are interpolated with a linear curve.
Smooth: Point Field Magnitude values are interpolated along a bell curve, so that each value on the ramp dominates the region around it, then blends quickly to the next magnitude value.
Spline: Point Field Magnitude values are interpolated with a spline curve, taking neighboring indices into account for greater smoothness.

Point Field Scale Input

Specifies which attribute is used to map Point Field Scale ramp values.

Off: When off, the Point Field Scale ramp does not use per particle attributes as the input.
Age: The Point Field Scale input is determined by the nParticle age, which is based on the particle Lifespan mode. See Lifespan Attributes.
Normalized Age: The Point Field Scale input is determined by the normalized age of the nParticle. To use Normalized Age, the nParticle object must have a defined lifespan. For example, the nParticle object’s Lifespan Mode attribute must be set to Constant or Random range. See Lifespan Mode.

When Normalized Age is used, Point Field Scale is mapped within the range of the nParticle object’s lifespan.
Speed: The Point Field Scale input is determined by nParticle speed.
Acceleration: The Point Field Scale input is determined by nParticle acceleration.
Particle ID: The Point Field Scale input is determined by the nParticle’s index.
Randomizing ID: The Point Field Scale input is determined by a randomized nParticle ID.
Radius: The Point Field Scale input is determined by the nParticle’s radius.

Input Max: Sets the maximum value for the range used by the Point Field Scale ramp.

Point Field Dropoff

Sets a ramp that specifies how much the Point Field Magnitude drops off as you move away from the nParticle and toward the edge of the area defined by Point Field Distance. See Working with nParticle attribute ramps.

Selected Position: This value indicates the amount of Point Field Dropoff on the ramp. The left position on ramp represents the amount Point Field Dropoff at the outside radius of the nParticles. The right position on the curve represents Point Field Dropoff at the edge of the Point Field Distance.
Selected Value: This value indicates the magnitude of the Point Force Field at the selected position.

Interpolation

Controls the way Point Field Dropoff blends between positions on the ramp. The default setting is Linear.

None: The Point Field Dropoff curve is flat between points.
Linear: Point Field Dropoff values are interpolated with a linear curve.
Smooth: Point Field Dropoff values are interpolated along a bell curve, so that each value on the ramp dominates the region around it, then blends quickly to the next magnitude value.
Spline: Point Field Dropoff values are interpolated with a spline curve, taking neighboring indices into account for greater smoothness.

Wind Field Generation

Air Push Distance

Specifies the distance over which the wind created by the motion of the current nParticle object affects nCloth objects or other nParticle objects in the same Nucleus system. The motion of the current nParticle object determines the direction of the wind.

When Air Push Distance is 0, no wind is generated by the motion of the current nParticles. When Air Push Distance is greater than 0, the wind created by the motion of the current nParticle object affects nCloth or other nParticle objects in the same Nucleus system. The higher the Air Push Distance, the greater the distance over which the wind created by the motion of the current nParticle object affects nCloth or other nParticle objects in the same Nucleus system.

Note

We recommend that you do not use Wind Shadow Distance and Air Push Distance together.
Air Push Distance is more processor-intensive than Wind Shadow Distance.
The effect of Air Push Distance is relative to the wind velocity, so a stationary object will slow down the wind within the push distance.

Air Push Vorticity

Specifies the amount of circulation or rotation in the flow of air being pushed by the current nParticle object, as well as the amount of curl in the flow of wind created by the motion of the current nParticle object. Air Push Vorticity changes the direction of the wind created by the motion of the current nParticle object.

Air Push Vorticity only affect’s your nParticles when Air Push Distance is greater than 0.

Wind Shadow Distance

Specifies the distance over which the current nParticle object blocks the dynamic wind of its Nucleus system from other nParticle, nCloth, and passive objects in its system.

When Wind Shadow Distance is 0, no wind is blocked by the current nParticle object. When Wind Shadow Distance is greater than 0, the dynamic wind of its Nucleus system is blocked by the current nParticle object. The higher the Wind Shadow Distance, the greater the distance for which the current nParticle object blocks the dynamic wind of its Nucleus system.

Wind Shadow Diffusion

Specifies the amount the dynamic wind curls around the current nParticle object as it blocks the dynamic wind of its Nucleus system.

Wind Self Shadow

When on, the current nParticle object blocks the dynamic wind of its Nucleus system from affecting itself.

Liquid Simulation

Enable Liquid Simulation: When turned on, Liquid Simulation properties are added to the nParticle object. See Liquid Simulation properties.
Incompressibility: Specifies the amount liquid nParticles resist compression. For water-like liquids, use low values. Increasing Substeps on the nucleus node magnifies the affect of Incompressibility.
Viscosity: Viscosity represents the resistance of the liquid to flow, or how thick, and non-liquid the material is. When this value is high, the liquid flows like tar. When this value is small, the liquid flows more like water. For example, a value of 0.01 produces water-like liquids. For more viscous liquids, use a value of 0.1.

Increasing Substeps on the nucleus node magnifies the affect of Viscosity.
Rest Density: Sets the arrangement of nParticles in the liquid when the nParticle object is at rest. A Rest Density of 2 specifies that, when the nParticles are settled, on average, there would be 2 nParticles overlapping at any point. A value of 2.0 provides good results for most liquids.
Liquid Radius Scale: Specifies the amount of overlap of nParticles based on nParticle Radius. Lower values increase overlap between nParticles. A value 0.5 provides good results for most liquids.

Output Mesh

Output Mesh attributes allow you to control the size, smoothness, and dynamic characteristics of Blobby Surface nParticle objects when they are converted to polygon meshes. To see the effects of Output Mesh settings, you must first convert your nParticle object to a polygon mesh by selecting Modify > Convert > nParticles to Polygons. nParticles must be either created or emitted into the scene to be converted to polygons. nParticles emitted after the conversion will continue to add to the size and overall appearance of the nParticle output mesh. Output Mesh attributes are applicable all Particle Render Type nParticles. However the nParticle output mesh always creates an iso-surface, which is based on nParticle Radius and Threshold.

Threshold: Determines the smoothness of the surface created by overlapping Blobby Surface nParticles. Threshold is based on the overall density of overlapping nParticles. Each nParticle has a density of 1 at its center, which then falls off to a value of 0 at the nParticle's edge.
Blobby Radius Scale: Specifies the amount nParticle Radius is scaled to create an appropriately smooth surface on Blobby Surface nParticles. Increasing Blobby Scale Radius does not affect nParticle Radius, meaning that nParticles can overlap due to Blobby Scale Radius without affecting their dynamic behavior. Increasing Blobby Scale Radius and Threshold together create smooth surfaces on nParticle output meshes.
Motion Streak: Motion Streak elongates individual nParticles based on the direction of nParticle motion, as well as the distance the nParticle travels in one time step. When Motion Streak is 0, nParticles are round. When Motion Streak is 1, nParticles are elongated to a length that is equal to the distance travelled in one time step. Motion Streak applies only to nParticles converted to nParticle output meshes. Motion Streak is useful for creating a motion blur type of effect, and for shaping the flow of Liquid Simulation effects.
Mesh Triangle Size: Determines the size of the triangles used to create the nParticle output mesh. Small Mesh Triangle Size produces high resolution nParticle output meshes with smoother surfaces, however small triangles take more computing resources and time to simulate. Mesh Triangle Size can be affected if the particle system bounds are very large relative to the set Mesh Triangle Size. See Max Triangle Resolution.
Max Triangle Resolution: Specifies the grid size that is used to create the nParticle output mesh. Max Triangle Resolution clamps the resolution of the voxel grid used in generating the nParticle output mesh's triangles. If the grid size required to create an nParticle mesh exceed the Max Triangle Resolution value, the output Mesh Triangle Size automatically increases to compensate for increasing size of the nParticle mesh.
Use Gradient Normals: Turn this attribute on to make the normals on an nParticle output mesh smoother. When on, the output mesh normals are created based on the direction of the opacity gradient within the particle density. This can improve the appearance of the nParticle output mesh, particularly in areas of the mesh that have thin triangles. This setting only affects the output nParticle mesh and not volume nParticle renders.

Mesh Method

Specifies the type of polygon mesh used to generate the nParticle output mesh iso-surface. By default, Mesh Method is set to Cubes.

Cubes: Converts nParticles to a cube polygon mesh using the marching cubes method.
Tetrahedra: Converts nParticles to a tetrahedral polygon mesh using the marching tetrahedra method.
Acutetetrahedra: Converts nParticles to tetrahedral polygon mesh using the marching tetrahedra method, and produces a slightly higher resolution mesh than the Tetrahedra Mesh Method.
Quads: Converts nParticles to a quad polygon mesh.

Mesh Smoothing Iterations: Specifies the amount of smoothing applied to the nParticle output mesh. Smooth iterations increase the lengths of the triangle edges, making the topology more uniform, generating a smoother iso-surface. The smoothness of your nParticle output mesh increases with increased Mesh Smoothing Iterations values, however, however, calculation time also increases.

Caching

Specifies the simulation data that will be saved to a server or local hard drive when the current nParticle object is nCached.

Cacheable Attributes

Position: Caches Particle ID, Age, and position.
Position and Velocity: Caches Particle ID, Age, position, velocity, and Lifespan(PP).
Dynamics and Rendering: Caches the following nParticle attribute data: Mass, radiusPP, opacityPP, rgbPP, incandescencePP, spriteNumPP, spriteScaleXPP, and spriteScaleYPP.
All: This caching option is currently not yet supported.

Memory Cache: When turned on, the motion your nParticle object is saved to memory (not to disk). If you cache data in memory for emitted nParticles, and then later change the rate or another attribute of the emitter or emitted nParticles, you must disable the cache to see the effect of the attribute change.

Emission Attributes

Max Count: See Max Count.
Level Of Detail: See Level Of Detail.
Inherit Factor: See Inherit Factor.
Emission In World: See Emission In World.
Die On Emission Volume Exit: See Die on Emission Volume Exit.
Emission Overlap Pruning: Removes newly emitted nParticles before they appear in the simulation based how much they will overlap with existing nParticles. This value scales the collision radius used to determine overlap. A value of 1.0 it guarantees no self collisions with other particles on emission.

Emission Random Stream Seeds

emitter: See Work with emission randomness.

Shading

Particle Render Type: See Particle Render Type.
Depth Sort: See Depth Sort.
Threshold: Determines the smoothness of the surface created by overlapping Blobby Surface nParticles. Threshold is based on the overall density of overlapping nParticles. Each nParticle has a density of 1 at its center, which then falls off to a value of 0 at the nParticle's edge.
Opacity: Sets the overall nParticle opacity.

Opacity Scale

The Opacity Scale ramp sets per particle opacity scale values which are applied to the Opacity attribute to compute per particle opacity values. The vertical component represents the Opacity Scale values from 0 (no opacity) to 1 (equal to the Opacity attribute value). Working with nParticle attribute ramps.

Selected Position: This value indicates the position of the selected opacity on the ramp (between 0 on the left to 1 on the right).
Selected Value: This value indicates per particle opacity on the ramp at the selected position.

Interpolation

Controls the way per particle opacity blends between positions on the ramp. The default setting is Linear.

None: The Opacity Scale curve is flat between points.
Linear: Opacity Scale values are interpolated with a linear curve.
Smooth: Opacity Scale values are interpolated along a bell curve so that each opacity value on the ramp dominates the region around it, and then blends quickly to the next value.
Spline: Opacity Scale values are interpolated with a spline curve, taking neighboring indices into account for greater smoothness.

Opacity Scale Input

Specifies which attribute is used to map Opacity Scale ramp values.

Off: When off, the per particle opacity attributes are deleted. If you want to use an expression with opacity, you need to manually add the opacity per particle attributes again.
Age: Per particle opacity is determined by the particle age, which is based on the particle Lifespan mode. See Lifespan Attributes.
Normalized Age: Per particle opacity is determined by the normalized age of the nParticle. To use Normalized Age, the nParticle object must have a defined lifespan. For example, the nParticle object’s Lifespan Mode attribute must be set to Constant or Random range. See Lifespan Mode.

When Normalized Age is used, per particle opacity is mapped within the range of the nParticle object’s lifespan.
Speed: Per particle opacity is determined by particle speed.
Acceleration: The per particle opacity is determined by particle acceleration.
Particle ID: Per particle opacity is determined by particle ID. Particle IDs are unique and generated at the beginning of the particle's lifespan.
Randomized ID: Per particle opacity is determined by a randomized nParticle ID.
Radius: Per particle opacity is determined by the nParticle’s Radius.

Input Max: Sets the maximum value for the range used by the Opacity Scale ramp.
Opacity Scale Randomize: Sets a random value multiplier for the per particle opacity scale values.

Color

The Color ramp defines a range of color values used for nParticle. The particular colors selected from this range correspond with the values for the selected Color Input. Color Input values of 0 map to the color at the left of the ramp, Color Input values of 1 map to the color at the right of the ramp, and values between 0 and 1 map to the color corresponding with the position on the ramp. Working with nParticle attribute ramps.

Selected Position: This value indicates the position of the selected color on the ramp (between 0 on the left to 1 on the right).
Selected Color: Indicates the color on the ramp at the selected position. To change the color, click the Selected Color box, and then select a new color from Color Chooser.

Interpolation

Controls the way colors blend between positions on the ramp. The default setting is Linear.

None: The color curve is flat between points.
Linear: Color values are interpolated with a linear curve.
Smooth: Color values are interpolated along a bell curve so that each color on the ramp dominates the region around it, then blends quickly to the next color.
Spline: Color values are interpolated with a spline curve, taking the colors at neighboring position markers into account for a smoother transition.

Color Input

Specifies which attribute is used to map the ramp's color values.

Constant: Per particle color is set to a single color value determined by the currently selected ramp position.
Age: Per particle color is determined by the particle age, which is based on the nParticle Lifespan mode. See Lifespan Attributes.
Normalized Age: Per particle color is determined by the normalized age of the nParticle. To use Normalized Age, the nParticle object must have a defined lifespan. For example, the nParticle object’s Lifespan Mode attribute must be set to Constant or Random range. See Lifespan Mode.

When Normalized Age is used, per particle color is mapped within the range of the nParticle object’s lifespan.
Speed: Per particle color is determined by nParticle speed.
Acceleration: Per particle color is determined by nParticle acceleration.
Particle ID: Per particle color is determined by nParticle ID. Particle IDs are unique and generated at the beginning of the particle's lifespan.
Randomized ID: Per particle color is determined by a randomized particle ID.
Radius: Per particle color is determined by the nParticle's radius.

Input Max: Sets a maximum multiplier for the range of RGB color values used by the Color ramp.
Color Randomize: Sets a random value multiplier for the per particle color values.

Incandescence

Incandescence controls the amount and color of light emitted from the nParticles due to self illumination. The particular colors selected from this range correspond with the values for the selected Incandescence Input. Incandescent emission is not affected by illumination or shadowing. If the Incandescence Input is set to Off, the per particle attributes are deleted. If it is set to any other value, the incandescence per particle attributes are created if they don't already exist. Working with nParticle attribute ramps.

Selected Position: This value indicates the position of the selected color on the ramp (between 0 on the left to 1 on the right).
Selected Color: Indicates the color on the ramp at the selected position. To change the color, click the Selected Color box, and then select a new color from Color Chooser.

Interpolation

Controls the way colors blend between each position on the ramp. The default setting is Linear.

None: The color curve is flat between points.
Linear: The color values are interpolated with a linear curve.
Smooth: Color values are interpolated along a bell curve so that each color on the ramp dominates the region around it, then blends quickly to the next color.
Spline: Color values are interpolated with a spline curve, taking the colors at neighboring position markers into account for a smoother transition.

Incandescence Input

Specifies which attribute is used to map the ramp's color values.

Off: When off, the per particle incandescence attributes are deleted. If you want to use an expression with incandescence, you need to manually add the incandescence per particle attributes again.
Age: Per particle incandescent color is determined by the particle age, which is based on the particle Lifespan mode. See Lifespan Attributes.
Normalized Age: Per particle incandescent color is determined by the normalized age of the nParticle. To use Normalized Age, the nParticle object must have a defined lifespan. For example, the nParticle object’s Lifespan Mode attribute must be set to Constant or Random range. See Lifespan Mode.

When Normalized Age is used, per particle incandescent color is mapped within the range of the nParticle object’s lifespan.
Speed: Per particle incandescent color is determined by nParticle speed.
Acceleration: Per particle incandescent color is determined by nParticle acceleration.
Particle ID: Per particle incandescent color is determined by nParticle ID. Particle IDs are unique and generated at the beginning of the particle's lifespan.
Randomized ID: Per particle incandescent color is determined by a randomized particle ID.
Radius: Per particle incandescent color is determined by the nParticle's radius.

Input Max: Sets a maximum multiplier for the range of RGB color values used by the Incandescence ramp.
Incandescence Randomize: Sets a random value multiplier for the per particle incandescence values.

Per Particle Attributes

See Set attributes on a per particle basisand Per particle and per object attributes.

Details on particle expressions can be found in the MEL and Expressions book.

Add Dynamic Attributes

See Add custom attributes.

Goal Weights and Objects

See Goal Weights and Objects.

Instancer (Geometry Replacement)

See Instancer (Geometry Replacement).

Render Attributes

See Render Attributes.

Render Stats

See Render Stats.

mental ray

See mental ray in the Rendering guide for more information.