Motion Inherit Operator 

The Motion Inheritance Operator is intended to create effects where objects interact with particles. Any 3ds Max object can affect particles or particle Groups in thinkingParticles. Any 3ds Max object can also control or add its speed or rotation to a set of particles. A good example of this is seeing bubbles being swept through a propeller on a boat. The motion of the particles is driven by the rotation of the prop, and in thinkingParticles, instead of having to "fake" such an effect, you can use real physics to achieve it instead.

Operator Inputs 

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 influenced by the object piped in through the Node input data stream. The data stream MUST be connected and will be highlighted yellow if it is not.

Node - (Node) This input data stream is used to get the selected object by which the particles are to be influenced. The data stream MUST be connected and will be highlighted yellow if it is not.

Inheritance - (Scalar) This input data stream is used to override the Inheritance [%] spinner value.

Motion Variation - (Scalar) This input data stream is used to override the Variation [%] spinner value (the one directly beneath the Inheritance spinner).

Rotation Inheritance - (Scalar) This input data stream is used to override the Rotational Inh.[%] spinner value.

Rotation Variation - (Scalar) This input data stream is used to override the Variation [%] spinner value (the one directly beneath the Rotation Inh. spinner).

Direction Variation - (Angle) This input data stream is used to override the Direction [*] angular spinner value.

Distance Type - (Integer) This input data stream takes an integer value that represents the force field boundary type that will control the selected object's influence over the particles. Valid input values are 0 through 2, where:

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

Radius Gradient - (Alpha Gradient) This input data stream is used to override the Gradient used for the Radial influence of the Motion Inheritance. Be aware that this gradient is only valid when the Distance type is set to Sphere.

Cylinder Axis - (Integer) This input data stream takes an integer value that represents the Primary Axis for a cylinder that is to surround the selected object. Valid input values are 0 through 2, where:

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

Height Gradient - (Alpha Gradient) This input data stream is used to override the Gradient used for the height influence of the Motion Inheritance. Be aware that this gradient is only valid when the Distance type is set to Cylinder.

Scale Gradient - (Alpha Gradient) This input data stream is used to override the Gradient used for the scale influence of the Motion Inheritance. Be aware that this gradient is only valid when the Distance type is set to Cylinder.

Operator Outputs 

No Operator Outputs.

Rollout Menu 

Inheritance [%] - This spinner controls the amount of particle influence an object has. A value of 100 means that 100% of the speed and rotation is taken from the object that is piped into the Node input data stream.

Variation [%] - If you do not want all particles to be influenced by the exact same amount as set in the Inheritance % spinner, increase the Variation % up to 100 to give the particle motion some additional randomness.

Rotation Inh [%] - The Rotational Inheritance spinner determines how much of the rotational information is passed along to the individual particles. When doing particle animations that involve rotating objects (such as fans or propellers), generally you'll want to have some of that rotational information passed along to the individual particles. When set to 0.0, particles will be affected by the motion, but individual particles will not rotate.

Variation [%] - If you do not want all particles to be influenced by the exact same amount as set in the Rotation Inh % spinner, increase the Variation % up to 100 to give the particle rotations some additional randomness.

Dir. Variation [*] - Usually the direction is taken from the object - that is, assigned to the IDS-Node connector. For example, when the object moves to the right the particles move to the right (100% inheritance assumed). Increase this value to create a spread out effect and give the particles a random direction when they start interacting with the object.

Distance Type - In order to create Motion Inheritance, you will use a force field or boundary that will define the area within which to check for the inheritance. You may select one of three force field types that should encompass the object being used to determine Motion Inheritance.

None - If you select this option, the boundary will have no falloff function, and all particles are affected by the same amount as is set in the Inheritance % parameter.

Sphere - Selecting this option creates a spherical force field boundary around the object that should interact with the particles. The Falloff Gradient Ramp directly beneath this dropdown menu will control the influence falloff. This falloff is calculated from the center of the sphere to the outer edge. The gradient ramp reads left to right and corresponds as follows: the left edge of the gradient represents the center of the sphere, while the right edge of the gradient represents the outer edge of the sphere.

Cylinder - Selecting this option creates a cylindrical force field boundary around the object that should influence the particles. In this case, both falloff gradients are used to control the Motion Inheritance influence falloff in the X and Y directions.

Radius - This spinner defines the radius of the objects force field boundary (the volume of influence).

Gradient Ramp - When Distance Type is set to Sphere, you may set the influence falloff from center to the outer edges of the sphere volume. The gradient works like this: The left hand side of the gradient controls the influence amount in the center and the right hand side of the gradient controls the influence amount at the outer edges of the volume. A pure white color will use the value as it is set in the Inheritance % parameter. A pure black color will switch off any object influence. All grays cale values in between both colors will create intermediate influence amounts.

Cylinder Axis - These three options allow you to control the orientation of the cylinder volume.

IMPORTANT: You MUST set the Distance Type to Cylinder to make these parameters work. The cylinder volume is then displayed in the view port as a wire frame cylinder.

Cylinder Height - This parameter controls the height of the cylindrical volume of influence. You can see in the view ports the actual size of the volume as it is displayed as a wire-frame cylinder around the object that is chosen to interact with the particles.

Gradient Ramp - Use the gradient ramp below the Cylinder Height spinner to set the falloff amount of the influence the object has along the length of the cylinder volume as shown below.



Cylinder Scale - This gradient controls the falloff amount as seen from the center to the outer radial edges of the cylinder (see the illustration below). The gradient colors/ramps work like described above.