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74 Chapter 11: Space Warps and Particle Systems
Gravity effect on snow
Procedure
To create gravity:
1.
On the Create p anel, click Space
War ps. Choose Forces from the list, t hen on the
Object Type rollout, click Gravity.
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 w ireframe sphere.
The initial direction of planar g ravity is along
thenegativeZaxisoftheconstructiongrid
that is active in the view port w here 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 Gra vity icon’s direction arrow. Strength
less than 0.0 creates negative gra vity, 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 Gravity space
warp has the same st rength throughout world
space. Increasing the Decay va lue causes g ravity
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 throughout the scene.
Spherical—Gravity effect is spherical, centered on
theGravitywarpobject.Thischoiceiseffectivefor
creatingwaterfountainorplanetaryeffects.
Display group
Range Indicators—When on, and w hen the Decay
value is greater than 0.0, icons in the viewports
indicate the range at which the force of gravity is
half the maximum valu e. For the Planar option,
the indicators a re 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.