The Rolling Operator can be used to simulate two dynamic effects; the first is used to simulate a simple, natural rolling motion for each particle. The second effect that can be created with this operator is forcing a particle to stretch out by based on the speed it travels.

Natural rolling means that each particle's Edge Length is measured and is used to control the individual rolling speed. Bigger objects will roll slower than smaller ones.

ON - (Bool) This input data stream determines whether the operator is considered 'on' or 'off'. You can connect other operators to this input channel such as a Bool Helper to activate/deactivate the whole operator.

Time - (Time) This input data stream is used to define the local time for the operator when the user wants to override the default system time.

Particle - (Particle) This input data stream reads in the currently selected particle group that is to have its particles be affected by rolling forces. The data stream MUST be connected and will be highlighted yellow if it is not.

Type - (Integer) This input data stream takes an integer value that represents the Rolling type that will control the particles' rotational Primary Axis. Valid input values are 0 and 1, where:

• 0 = Rolling
• 1 = Direction of Travel

Laziness - (Scalar) This input data stream is used to override the Laziness spinner value.

Source - (Integer) This input data stream takes an integer value that represents the Primary Axis for the rolling dynamics. Valid input values are 0 through 2, where:

• 0 = X-Axis
• 1 = Y-Axis
• 2 = Z-Axis

Invert - (Bool) This input data stream is used to override the Invert check box state. Be aware that this stream is only valid when the Type of rolling is set to Direction of Travel.

Stretch - (Scalar) This input data stream is used to override the Stretch spinner value. Be aware that this stream is only valid when the Type of rolling is set to Direction of Travel.

Axis - (Direction) This input data stream is used to override the Invert check box state. Be aware that this stream is only valid when the Type of rolling is set to Rolling.

No Operator Outputs.

Rolling - When this option is chosen, you will be using a simple rolling algorithm to determine the amount of roll imparted to the particles you've selected.

Direction of Travel - Select this option when you want to have the rotation controlled by the vector formed by the direction in which each particle is moving. When selected, it will also activate both the Primary Axis selection and the Stretch parameter.

Laziness - Values greater than zero will simulate an effect like momentum of mass for each particle. The particles need some time to accelerate until they roll at their maximum speed. A 0.0 value makes the particles roll immediately after it receives a True condition.

P Axis - When Direction of Travel is selected, you are able to select a Primary Axis for rolling. With P-Axis, you may set any local particle rotation axis to be used for this effect.

Invert - As Albert Einstein noted some time ago: Everything is relative. This includes the local axis of the particle. Use the Invert button when you want to use the negative value of the selected P-Axis.

Stretch - When this spinner's value is greater than 0.0, the particles will stretch along the movement vector dependant on their speed. Specifically, the Stretch value specifies the percentage of their length per each unit of the Speed setting. Therefore, if you set this to 2 while Speed is set at 10, the particles are stretched 20 percent longer than their original size along the axis of their travel. This spinner is only enabled when Direction of Travel is chosen. Negative values are also allowed and this will create a squeezing effect on the particles.

X / Y / Z Axis - Specifies the rolling vector of the X, Y, and Z axes, respectively. These spinners and the Variation spinner are only enabled when Rolling is chosen.