To create a vortex control object: Choose Get > Force > Vortex from the Simulate toolbar, Get > Primitive > Control Object > Vortex from the other toolbars, or Create > Force > Vortex from the Hair toolbar.
To redisplay: Select the vortex object and press Enter.
The Vortex force simulates the swirling movement of a vortex on particles and hair.
Vortex has no effect on Fluid, Explosion, Soft body, or Cloth simulations.
For more information on forces in general, see Forces for Simulations.
To use this force in an ICE tree, see Creating and Applying Forces to ICE Simulations [ ICE ].
|
Name |
The name of the force effect |
|
Mute |
Toggles on/off the force effect. |
Strength
|
Amplitude |
Sets the strength of the vortex effect. |
|
Radial |
Defines the amount of force along the radial direction; negative values attract objects toward the cylinder axis, positive values make objects escape from it. |
Influence
|
Local |
Select this option to have the vortex force affect only simulated objects that fall within the Range that you specify (see below). If you don’t select this option, all simulated objects are affected by the vortex force (global). |
|
Range |
Sets the range in Softimage units within which the vortex force has an effect on the simulated objects. This control is available only when Local is selected. |
|
Decay |
Allows you to have the maximum force at the center and minimum at the edges, or the reverse (with negative values) with minimum force at the center and maximum at the edges. |
Vortex Calculations
Inputs:
vPos = particle's position vector
vVel = particle's velocity vector
Outputs:
vForce = the new force
If Local is selected:
length = vPos.length
// two steps
1. radialDecay = length / range
2. radialDecay = (decay >= 0) ? (1 - radialDecay) ^ decay : radialDecay ^ -decay
intensity = amplitude * radialDecay
vIntensity = (intensity, 0, 0)
vDirection = crossProduct(vVel, vIntensity) vRadialDir = (5 * radial) * ( normalize(0, vPos.Y, vPos.X) )
vForce = vRadialDir + vDirection
If Local is not selected (global):
length = intensity / (1 + vPos.length ^ 3) vDirection = cross(vVel, vPos) vRadialDir = radial * ( normalize (vPos) )
vForce = intensity * (vRadialDir + vDirection)
Autodesk Softimage v.7.5