air

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Synopsis

air [-attenuation float] [-directionX float] [-directionY float] [-directionZ float] [-enableSpread boolean] [-fanSetup] [-inheritRotation boolean] [-inheritVelocity float] [-magnitude float] [-maxDistance linear] [-name string] [-perVertex boolean] [-position linear linear linear] [-speed float] [-spread float] [-torusSectionRadius linear] [-velocityComponentOnly boolean] [-volumeExclusion boolean] [-volumeOffset linear linear linear] [-volumeShape string] [-volumeSweep angle] [-wakeSetup] [-windSetup] [objects]

air is undoable, queryable, and editable.

If fields are created, this command returns the names of each owning shape and of the field shapes themselves. If a field was queried, the results of the query are returned. If a field was edited, the field name is returned.

If no object names are provided but the active selection list is non-empty, the command creates a field for every object in the list. If the list is empty, the command defaults to -pos 0 0 0. The air field simulates the effects of moving air. The affected objects will be accelerated or decelerated so that their velocities match that of the air.

With the '-vco true' flag thrown, only accelerations are applied. By parenting an air field to a moving part of an object (ie. a foot of a character) and using '-i 1 -m 0 -s .5 -vco true' flags, one can simulate the movement of air around the foot as it moves, since the TOTAL velocity vector of the field would be only based on the movement of the foot. This can be done while the character walks through leaves or dust on the ground.

For each listed object, the command creates a new field. The transform is the associated dependency node. Use connectDynamic to cause the field to affect a dynamic object.

If fields are created, this command returns the field names. If a field was queried, the results of the query are returned. If a field was edited, the field name is returned.

If the -pos flag is specified, a field is created at the position specified. If not, if object names are provided or the active selection list is non-empty, the command creates a field for every object in the list and calls addDynamic to add it to the object; otherwise the command defaults to -pos 0 0 0.

Setting the -pos flag with objects named on the command line is an error.

Return value

In query mode, return type is based on queried flag.

Related

Flags

Long name (short name)	Argument types	Properties
-attenuation(-att)	float
Attentuation rate of field
-directionX(-dx)	float
-directionY(-dy)	float
-directionZ(-dz)	float
Direction that the air will try to match the affected particles' velocity to. NOTE: This is not the velocity; this is only the direction. Use the -s flag to set the speed.
-enableSpread(-es)	boolean
This tells the system whether or not to use the spread angle given by '-sp'. If this is 'false' then all connected objectswithin the maximum distance will be affected. Also, if this is set to 'false', all affected objects are forced to match their velocities along the direction vector. If this is set to 'true' and spread is used, then the direction of the force is along the direction from the field to the object.
-fanSetup(-fs)
Similar to 'windSetup' except that the effects of a fan or a person blowing air are approximated. The user can pass the same flags on the command line to adjust them from the defaults. These are the values that get set to approximate a 'fan': inheritVelocity 1.0 inheritRotation true componentOnly false enableSpread true spread .5 (45 degrees from center )
-inheritRotation(-iro)	boolean
If this is set to 'true', then the direction vector described with -dx, -dy, and -dz will be considered local to the owning object. Therefore, if the owning object's transform undergoes any rotation (by itself or one of its parents), the direction vector of the air field will undergo that same rotation.
-inheritVelocity(-iv)	float
Amount (from 0 to 1) of the field-owner's velocity added to the vector determined by the direction and speed flags. The combination of these two vectors makes up the TOTAL velocity vector for the air field. This allows the air to be determined directly by the motion of the owning object.
-magnitude(-m)	float
Strength of field.
-maxDistance(-mxd)	linear
Maximum distance at which field is exerted. -1 indicates that the field has no maximum distance.
-name(-n)	string
name of field
-perVertex(-pv)	boolean
Per-vertex application. If this flag is set true, then each individual point (CV, particle, vertex,etc.) of the chosen object exerts an identical copy of the force field. If this flag is set to false, then the froce is exerted only from the geometric center of the set of points.
-position(-pos)	linear linear linear
Position in space (x,y,z) where you want to place a gravity field. The gravity then emanates from this position in space rather than from an object. Note that you can both use -pos (creating a field at a position) and also provide object names.
-speed(-s)	float
How fast the affected objects' speed reaches the speed (based on the -mag, -dx, -dy, -dz flags) of the air field. This value gets clamped internally to be between 0.0 and 1.0. A value of 0.0 will make the air field have no effect. A value of 1.0 will try to match the air field's speed much quicker, but not necessarily immediately.
-spread(-sp)	float
This represents the angle from the direction vector within which objects will be affected. The values are in the range of 0 to 1. A value of 0 will result in an effect only exactly in front of the air field along the direction vector. A value of 1 will result in any object in front of the owning object, 90 degrees in all direction from the direction vector.
-torusSectionRadius(-tsr)	linear
Section radius for a torus volume. Applies only to torus. Similar to the section radius in the torus modelling primitive.
-velocityComponentOnly(-vco)	boolean
If this is 'false', the air will accelerate or decelerate the affected objects so that their velocities will eventually match the TOTAL velocity vector of the air field. If this is 'true', only ACCELERTION is applied to the affected objects so that their velocity component along the TOTAL velocity vector matches or is greater in magnitude than the TOTAL velocity vector. This will not slow objects down to match velocities, only speed them up to match components. This is most useful when using the -iv flag with a value >0.
-volumeExclusion(-vex)	boolean
Volume exclusion of the field. If true, points outside the volume (defined by the volume shape attribute) are affected, If false, points inside the volume are affected. Has no effect if volumeShape is set to "none."
-volumeOffset(-vof)	linear linear linear
Volume offset of the field. Volume offset translates the field's volume by the specified amount from the actual field location. This is in the field's local space.
-volumeShape(-vsh)	string
Volume shape of the field. Sets/edits/queries the field's volume shape attribute. If set to any value other than "none", determines a 3-D volume within which the field has effect. Values are: "none," "cube," "sphere," "cylinder," "cone," "torus."
-volumeSweep(-vsw)	angle
Volume sweep of the field. Applies only to sphere, cone, cylinder, and torus. Similar effect to the sweep attribute in modelling.
-wakeSetup(-wks)
Like the 'windSetup' and 'fanSetup', 'wakeSetup' sets certain values in the field to approximate the movement of air near a moving object, such as a character's foot or hand. The values that are set are: inheritVelocity 1.0 inheritRotation false componentOnly true enableSpread false speed 0.0
-windSetup(-wns)
This will set some of the values above in a way that approximates the effects of a basic wind. This allows the user to then change certain values as he/she wishes on the same command line. First the preset values get set, and then any other flags that were passed get taken into account. These are the values that get set to approximate 'wind': inheritVelocity 0.0 inheritRotation true componentOnly false enableSpread false

Flag can appear in Create mode of command	Flag can appear in Edit mode of command
Flag can appear in Query mode of command	Flag can be used more than once in a command.

MEL examples

air -m 5.0 -mxd 2.0 particle1;
// Creates an air field with magnitude 5.0 and maximum distance 2.0,
// and adds it to the list
// of fields particle1 owns.

air -wakeSetup;
// Creates an air field with no no velocity in and of itself (magnitude = 0).
// All of the air's
// velocity is derived from the motion of the objects that own the field.