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70 Chapter 11: Space Warps and Particle Systems
Gravity effect on snow
Procedure
To create gravity:
1.
On the Create panel, click Space
Warps. Choose Forces from the list, then on the
Object Type rollout, click Gravit y.
2. Drag in a viewport.
The Gravity icon appears. For planar gravity
(the default), the icon is a wireframe square
with a direction arrow on one side. For
spherical gravity, the icon is a wireframe sphere.
The initial direction of planar gravity is along
thenegativeZaxisoftheconstructiongrid
that is active in the viewport where you drag.
You can rotate the gravity object to change the
direction.
Inter face
Force group
Strength—Increasing Strength increases the effect
of gravity; that is, how objects move in relation
to the Gravity icon’s direction arrow. Strength
less than 0.0 creates negative gravity, which repels
particlesmovinginthesamedirectionandattracts
particlesmovingintheoppositedirection.When
Strength is set to 0.0, the Gravity space warp has
no effect.
Decay—When Decay is set to 0.0, the Gravit y space
warp has the same strength throughout world
space. Increasing the Decay value causes gravity
strength to diminish as distance increases from the
position of the gravity warp object. Default=0.0.
Planar—Gravity effect is perpendicular to the plane
of the Gravity warp object t hroughout the scene.
Spherical—Grav ity effect is spherical, centered on
theGravitywarpobject.Thischoiceiseffectivefor
creatingwaterfountainorplanetaryeffects.
Display group
Range Indicators—When on, and when the Decay
value is greater than 0.0, icons in the v iewports
indicate the range at which the force of gravity is
half the maximum value. For the Planar option,
the i ndicators are two planes; for use the Spherical
option, the indicator is a double-hooped sphere.
Icon Size—Size of the Gravity warp object icon, in
active units. You set the initial size when you drag
to create the Gravity object. This value does not
change the gravity effect.