nucleus

 
 
 

This node is the general solver node used for Maya Nucleus objects including nCloth and nParticles. It contains settings to control forces (gravity and wind), ground plane attributes, and time and scale attributes, which apply to all of the Nucleus object nodes connected to a particular nucleus solver.

Enable

When turned on the current Nucleus solver calculates simulation data for the Nucleus objects that are part of its Nucleus system. When turned off, the current Nucleus solver does not calculate simulation data, and none of the Nucleus objects that are part of its Nucleus system are simulated.

Visibility

When on, the location and direction of Gravity and Wind are displayed as arrows in the scene. Visibility also displays the location of the Nucleus plane when Use Plane is on.

Turning Visibility on and off is the same as turning the Object Display Visibility attribute on and off. See Display.

NoteFor some workflows it is convenient to turn Visibility off, especially when selecting Nucleus objects assigned to the node. When Visibility is on, Maya's selection priority results in the Nucleus node being selected before its assigned objects in the scene.

Translate Attributes

Translate

Specifies the object’s translation (Translate X, Y, and Z) attribute values in world space.

Rotate

Specifies the rotation (Rotate X, Y, and Z attribute values) of the object in world space.

Scale

Specifies the objects’s scale (Scale X, Y, and Z) attribute values in world space.

Rotate Order

Specifies the object’s rotation order. You can set the rotate order when you want a specific final rotation for an object, because each rotate order option produces a different end orientation. For example, if the rotation order for an object is set to xyz, the object first rotates about its X-axis, then its Y-axis, and finally its Z-axis. Default is xyz.

Rotate Axis

Offsets the orientation of the object relative to the orientation of the object’s local rotation axis.

Inherits Transform

When this attribute is on, the current object inherits the transformations (Translate, Rotate, Scale, and Shear values) of its parent object.

Gravity and Wind

Gravity

Specifies the amount of gravity applied for this Maya®Nucleus solver. A value of 0.0 means there is no gravity. The default value is 9.8, which simulates the gravity of Earth.

Gravity interprets Maya’s units as meters. When the working units of your Nucleus object’s scene is not set to meters (such as Maya’s default centimeter working unit), you may need to adjust the Space Scaleof your Maya Nucleus solver. Otherwise, the large-sized Nucleus objects in your scene may not behave as desired. For example, when Space Scale is 1.0 (default), Gravity treats a 100 centimeter wide nCloth object like it is 100 meters wide. To improve the behavior of your large-sized nCloth objects, reduce the Space Scale value.

Gravity Direction

Specifies on which axis (X, Y or Z) the force of gravity applies. The default XYZ values are 0, -1, 0, meaning the gravity applies on the Y-axis, in the downward direction.

Air Density

Specifies the air density applied for this Maya Nucleus solver. Air density refers to the mass of the atmosphere in your scene, which affects the relative drag on an object. The default value is 1.

Low Air Density values decrease the amount of air friction acting on an object, which reduces the affect of drag. For example, setting Air Density to 0 creates an atmosphere similar to a vacuum, where there are no air molecules to collide with objects. High Air Density values increase air friction and drag on an object. For example, high values can be used to simulate an object's movement underwater.

Note

Air Density affects the Drag and Lift attributes on nCloth and nParticle objects. An Air Density value of 0.0 essentially turns these attributes off.

Wind Speed

Specifies the wind speed applied for this Maya Nucleus solver. The wind speed determines the force and intensity of the wind. A higher value means a fast wind speed, which has a more pronounced effect. Typical values are between 0-1.

Wind Direction

Specifies the direction in which the wind travels (X, Y or Z axis). The default value is 1, 0, 0, meaning the wind travels along the X axis, from left to right.

Wind Noise

Specifies the level of randomization for the dynamic wind of the current Nucleus system.

Ground Plane

Use Plane

When on, indicates that the ground plane is used in collisions for this Maya Nucleus solver. The ground plane acts as a collision object, without actually being geometry in your scene.

Plane Origin

Specifies the X, Y and Z axis coordinates for the origin of the ground plane used in collisions for this nucleus solver. The default value is 0, 0, 0, making the plane origin the same as the grid origin.

Plane Normal

Specifies the orientation of the ground plane used in collisions for this nucleus solver. The normal defines an imaginary line perpendicular to the surface of the plane. The normal has as an upward influence relative to the plane so that when objects are below the plane, (the negative normal side) they will be pushed above the plane (the positive normal side). The default value is 0, 1, 0.

Plane Bounce

Specifies the amount of deflective force the ground plane used in collisions has for this Maya Nucleus solver. The greater the Plane Bounce value, the more that an object colliding with the ground plane is deflected or bounced. Typical values are between 0-1.

Plane Friction

Specifies the amount of friction the ground plane used in collisions has for this Maya Nucleus solver. Plane Friction determines how much the ground plane resists relative motion upon contact with another object.

The amount of Plane Friction the ground plane requires is determined by what type of surface the ground plane represents. For example, a smooth surface like glass requires a low Plane Friction value, like 0. A fairly rough surface like asphalt requires a higher Plane Friction value, like 1. Plane Friction is 0.1 by default.

Plane Stickiness

Plane Stickiness determines the degree to which Nucleus objects in the current Nucleus system adhere to the ground plane when they collide with it.

Solver Attributes

Substeps

Specifies the number of times this Maya Nucleus solver calculates per frame. Substeps are useful with fast-moving objects with quick collisions, which might be missed if only calculated once per frame. A high number of substeps may result in a slower solve. The default value is 3.

Max Collision Iterations

Specifies the maximum number of collision iterations per simulation step for this Maya Nucleus solver. Iterations are the number of calculations occurring within a step, specifically the collision iterations (all types of collisions). Accuracy increases with increased iterations, however, calculation time also increases. The default value is 4.

There is always at least one collision iteration per substep, unless the Max Collision Iteration value is 0, which turns collisions off.

Collision Layer Range

Determines how close two objects must be in order for them to intercollide. If the differential between the Collision Layer values (set on the nClothShape and nParticleShape nodes) for the two objects is less than the Collision Layer Range, the objects can intercollide. The default value is 4.

For example, object A has a Collision Layer value of 2, while object B has a Collision Layer value of 5. The differential between the Collision Layer values is 3, therefore they can only collide when the Collision Layer Range value is equal to, or greater than 3.

Timing Output

Outputs Nucleus node timing information (in seconds) to the Script Editor.

None

No timing information is output to the Script Editor.

Frame

The following Nucleus node timing information (in seconds) is output to the Script Editor: the time spent solving each frame and the total time the Nucleus node spent evaluating the simulation since the initial frame.

Subframe

The following Nucleus node timing information (in seconds) is output to the Script Editor: the time spent solving each substep, the lapsed time since the beginning of the current frame, the time spent solving each frame, and the total time the Nucleus node spent evaluating the simulation since the initial frame.

Use Transform

When on, the Nucleus node Transform Attributes are used by the solver. You can set the Transform Attributes to specify the location that is affected by Nucleus gravity and wind. The area affected by the Nucleus force is determined by the bounding box in the location defined by the Translate X, Y, and Z values.

When Use Transform is on, you can create parent-child relationships with other objects in your scene. When you parent the transform node to another object, the simulation takes place in the local space of the Nucleus node, rather than in worldspace.

NoteBe aware that using the Transform Attributes affects how Nucleus forces are applied to all objects assigned to the solver. For example, using Rotate X, Y, or Z to change the direction of Gravity affects the orientation of the Nucleus Ground Plane for all assigned objects. Use Gravity Direction and Wind Direction to change the direction of forces rather than the Nucleus node Transform Attributes. See Gravity Direction and Wind Direction.

Time Attributes

Current Time

Lets you speed up or slow down dynamic animation for all objects connected to this Maya Nucleus solver.

Each object has a Current Time attribute that you can animate to slow or quicken its effects. This attribute contains the value of an independent clock time. In essence, you slow or speed the object’s clock to slow or speed the dynamics that affect it.

Start Frame

Specifies at what frame this Maya Nucleus solver starts calculating.

Frame Jump Limit

Specifies the maximum number of frames that make up one solver step. For time jumps of less than the Frame Jump Limit, the solver evaluates the current frame of the simulation. For time jumps larger than the Frame Jump Limit value, the solver does not compute a simulation and Maya displays a Nucleus evaluation skipped, frame change too large message.

Adjusting Frame Jump Limit to values great than 1.0 let you select advanced frames on the Timeline and obtain an approximate simulation of the frame(s) for preview purposes and can provide better results for scrubbing through the simulation.

Caching your simulation provides the most accurate results for viewing it at a fixed playback speed or by scrubbing the Timeline.

Scale Attributes

Time Scale

Determines the relative time nCloth and nParticle objects are running with respect to the Dependency Graph time. For example, if you want the cloth or to run through the simulation twice as fast, the Time Scale value should be set to 2. The longer the nCloth's simulation time is, the more force has an effect on the Cloth. For example, if the force is gravity, the nCloth will appear to be heavier as the Time Scale increases. The default value is 1.

Space Scale

Determines the relative space scale applied to this Maya Nucleus solver. The Maya Nucleus solver treats nCloth and nParticle objects as a scale model and applies the specified forces internally to get the expected behavior for the actual nCloth and nParticle objects at their actual size. The default value is 1.

Gravity interprets Maya’s units as meters. When the working units of your Nucleus object’s scene is not set to meters (such as Maya’s default centimeter working unit), you may need to adjust the Space Scale of your object’s Maya Nucleus solver. Otherwise, the large-sized nCloth or nParticle objects in your scene may not behave as desired. For example, when Space Scale is 1.0 (default), Gravity treats a 100 centimeter wide nCloth object like it is 100 meters wide. To improve the behavior of your large-sized nCloth objects, reduce the Space Scale value.

If you are modeling such that one unit is equal to one centimeter, the Space Scale value should be set to 0.01.