nParticle Collision attributes

By default, nParticles collide with passive collision, nCloth, nHair, other nParticle objects, as well, with itself (self collisions). For collisions to take place between nParticles and other Nucleus objects, the objects must be assigned to the same Nucleus solver, and the Collide attribute on their respective nodes must be turned on.

By default, nParticle objects can collide with nCloth objects, passive collision objects, other nParticle objects, as well, with itself (self collisions). For collisions to take place between nParticles and other Nucleus objects, the objects must be assigned to the same Nucleus solver, and the Collide attribute on their respective nodes must be turned on.

Collisions and Dynamic Properties are Nucleus-based attributes that determine the behavior of nParticles when they collide with Nucleus objects and how nParticles react to Nucleus-based forces. Although other attributes, such as Force Field Generation attributes may also affect how nParticles interact with other Nucleus objects, the Collisions and Dynamic Properties attributes are related to how the Nucleus solver calculates collision data in the simulation.

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.

Collide Strength

Specifies the strength of collisions between nParticles and other Nucleus objects. At the default value of 1, nParticles fully collide with each other and with other Nucleus objects. Collide Strength values between 0 and 1 dampen the full collision, while 0 turns off nParticle collisions (which has the same as effect as turning off the object's Collide attribute). Setting Collide Strength to values greater than 1 slightly increases the force of collisions, while values less than 0 can create a weak repulsive force between objects.

You can set Collide Strength on a per-particle basis with a Collide Strength Scale ramp.

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.

Note:

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

For information about collide layers, see nCloth Collision attributes.

Collide Width Scale

Specifies the collision thickness relative to the nParticle Radius value.

When set to 1.0, the collision width is equal to the Radius value. When set to 0.5 the collision width is half the Radius. Values less than 1.0 cause interpenetration with collision surfaces and overlap with other nParticle objects.

Self Collide Width Scale

Specifies the self-collide thickness relative to the nParticle Radius value.

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. Use Solver Display to help 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

Displays the collision volumes for the current nParticle object. Use Collision Thickness to visualize the thickness of colliding nParticles when tweaking nParticle collisions with other nParticle objects or nCloth and passive objects.

Self Collision Thickness

Displays the self-collision volumes for the current nParticle object. Use Self Collision Thickness to visualize nParticle self-collision thickness when tweaking self-colliding nParticles.

Display Color

Specifies the display color of the collision volumes.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

Bounce specifies 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.

Note:

Bounce values greater than 1.0 can cause instability and should be avoided.

Friction

Friction specifies 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 total amount of Friction used in a collision is the sum Friction value of the two colliding objects. The affect of Friction is influenced by the nParticle object’s Stickiness value.

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.

Self Collide must be on for particles from the same nParticle object to stick to each other.

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.

Collision Ramps

Collide Strength Scale

The Collide Strength Scale ramp sets per-particle collide strength scale values. These scale values are applied to the Collide Strength attribute to compute per-particle collide strength. The vertical component represents the Collide Strength Scale values from 0 (no collide strength) to 1 (equal to the Collide Strength attribute value). See Set attributes using ramps.

If the Collide Strength Scale Input is set to Off, the per-particle attributes are deleted. If it is set to any other value, the collide strength per-particle attributes are created if they don’t already exist.

Selected Position

Indicates the position of the selected value on the ramp (between 0 on the left to 1 on the right).

Selected Value

Indicates the per-particle attribute value on the ramp at the selected position.

Interpolation

Controls the way per-particle attribute values blend between each position on the ramp. The default setting is Linear.

None

The curve is flat between points.

Linear

The per-particle attribute values are interpolated with a linear curve.

Smooth

The per-particle attribute 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 value.

Spline

The per-particle attribute values are interpolated with a spline curve, taking neighboring indices into account for greater smoothness.

Collide Strength Scale Input

Specifies which attribute is used to map the Collide Strength Scale ramp values.

Off

When off, the per-particle attributes are deleted. If you want to use an expression with the per-particle attribute, you need to manually add them again. See About nParticle internal ramps and per-particle attributes.

Age

The per-particle attribute values are determined by the nParticle’s age, which is based on the particle Lifespan mode. See nParticle Lifespan attributes.

Normalized Age

The per-particle attribute values are 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.

When Normalized Age is used, The per-particle attribute values are mapped within the range of the nParticle object’s lifespan.

Speed

The per-particle attribute values are determined by nParticle speed.

Acceleration

The per-particle attribute values are determined by nParticle acceleration.

Particle ID

The per-particle attribute values are determined by the nParticle’s ID. Particle IDs are unique and generated at the beginning of the particle’s lifespan.

Randomizing ID

The per-particle attribute values are determined by a randomized nParticle ID.

Input Max

Sets the maximum value for the range used by the ramp.

Bounce Scale

The Bounce Scale ramp sets per-particle bounce scale values. These scale values are applied to the Bounce attribute to compute per-particle bounce. The vertical component represents the Bounce Scale values from 0 (no bounce) to 1 (equal to the Bounce attribute value). See Set attributes using ramps.

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

Selected Position

Indicates the position of the selected value on the ramp (between 0 on the left to 1 on the right).

Selected Value

Indicates the per-particle attribute value on the ramp at the selected position.

Interpolation

Controls the way per-particle attribute values blend between each position on the ramp. The default setting is Linear.

None

The curve is flat between points.

Linear

The per-particle attribute values are interpolated with a linear curve.

Smooth

The per-particle attribute 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 value.

Spline

The per-particle attribute values are interpolated with a spline curve, taking neighboring indices into account for greater smoothness.

Bounce Scale Input

Specifies which attribute is used to map the Bounce Scale ramp values.

Off

When off, the per-particle attributes are deleted. If you want to use an expression with the per-particle attribute, you need to manually add them again. See About nParticle internal ramps and per-particle attributes.

Age

The per-particle attribute values are determined by the nParticle’s age, which is based on the particle Lifespan mode. See nParticle Lifespan attributes.

Normalized Age

The per-particle attribute values are 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.

When Normalized Age is used, The per-particle attribute values are mapped within the range of the nParticle object’s lifespan.

Speed

The per-particle attribute values are determined by nParticle speed.

Acceleration

The per-particle attribute values are determined by nParticle acceleration.

Particle ID

The per-particle attribute values are determined by the nParticle’s ID. Particle IDs are unique and generated at the beginning of the particle’s lifespan.

Randomizing ID

The per-particle attribute values are determined by a randomized nParticle ID.

Input Max

Sets the maximum value for the range used by the ramp.

Friction Scale

The Friction Scale ramp sets per-particle friction scale values. These scale values are applied to the Friction attribute to compute per-particle friction. The vertical component represents the Friction Scale values from 0 (no friction) to 1 (equal to the Friction attribute value). See Set attributes using ramps.

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

Selected Position

Indicates the position of the selected value on the ramp (between 0 on the left to 1 on the right).

Selected Value

Indicates the per-particle attribute value on the ramp at the selected position.

Interpolation

Controls the way per-particle attribute values blend between each position on the ramp. The default setting is Linear.

None

The curve is flat between points.

Linear

The per-particle attribute values are interpolated with a linear curve.

Smooth

The per-particle attribute 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 value.

Spline

The per-particle attribute values are interpolated with a spline curve, taking neighboring indices into account for greater smoothness.

Friction Scale Input

Specifies which attribute is used to map the Friction Scale ramp values.

Off

When off, the per-particle attributes are deleted. If you want to use an expression with the per-particle attribute, you need to manually add them again. See About nParticle internal ramps and per-particle attributes.

Age

The per-particle attribute values are determined by the nParticle’s age, which is based on the particle Lifespan mode. See nParticle Lifespan attributes.

Normalized Age

The per-particle attribute values are 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.

When Normalized Age is used, The per-particle attribute values are mapped within the range of the nParticle object’s lifespan.

Speed

The per-particle attribute values are determined by nParticle speed.

Acceleration

The per-particle attribute values are determined by nParticle acceleration.

Particle ID

The per-particle attribute values are determined by the nParticle’s ID. Particle IDs are unique and generated at the beginning of the particle’s lifespan.

Randomizing ID

The per-particle attribute values are determined by a randomized nParticle ID.

Input Max

Sets the maximum value for the range used by the ramp.

Stickiness Scale

The Stickiness Scale ramp sets per-particle stickiness scale values. These scale values are applied to the Stickiness attribute to compute per-particle stickiness. The vertical component represents the Stickiness Scale values from 0 (no stickiness) to 1 (equal to the Stickiness attribute value). See Set attributes using ramps.

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

Selected Position

Indicates the position of the selected value on the ramp (between 0 on the left to 1 on the right).

Selected Value

Indicates the per-particle attribute value on the ramp at the selected position.

Interpolation

Controls the way per-particle attribute values blend between each position on the ramp. The default setting is Linear.

None

The curve is flat between points.

Linear

The per-particle attribute values are interpolated with a linear curve.

Smooth

The per-particle attribute 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 value.

Spline

The per-particle attribute values are interpolated with a spline curve, taking neighboring indices into account for greater smoothness.

Stickiness Scale Input

Specifies which attribute is used to map the Stickiness Scale ramp values.

Off

When off, the per-particle attributes are deleted. If you want to use an expression with the per-particle attribute, you need to manually add them again. See About nParticle internal ramps and per-particle attributes.

Age

The per-particle attribute values are determined by the nParticle’s age, which is based on the particle Lifespan mode. See nParticle Lifespan attributes.

Normalized Age

The per-particle attribute values are 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.

When Normalized Age is used, The per-particle attribute values are mapped within the range of the nParticle object’s lifespan.

Speed

The per-particle attribute values are determined by nParticle speed.

Acceleration

The per-particle attribute values are determined by nParticle acceleration.

Particle ID

The per-particle attribute values are determined by the nParticle’s ID. Particle IDs are unique and generated at the beginning of the particle’s lifespan.

Randomizing ID

The per-particle attribute values are determined by a randomized nParticle ID.

Input Max

Sets the maximum value for the range used by the ramp.