View Click Shape Facing in an event or add a
Shape Facing operator to the particle system and then select it.
The Shape Facing operator
creates each particle as a rectangle that always faces a particular
object, camera, or direction. For effects like smoke, fire, water,
bubbles, or snowflakes, use Shape Facing with a material containing
appropriate opacity and diffuse maps.
By default, the particles'
top and bottom sides are parallel to the horizontal plane. The Orientation
setting lets you change this default alignment.
NoteFor the Shape Facing
operator to be able to calculate the particle orientation, it must
know the current particle position. For this reason, always place
the Shape Facing operator below a
Position operator in an event.
Look At Camera/Object group
Use this control for
defining the camera or object toward which the particle will face.
This object is known as the Look At object.
For the technically minded, the facing is maintained by keeping
each particle's local Z axis pointed at the Look At object, or when
Use Parallel Direction is on, aligned with the vector between the
Particle Source icon and the Look At object.
After picking a Look
At object, its name appears here.
- Pick Camera or Object
Click this button, and then
select a camera or object in the scene to use as the Look At object.
The mouse cursor changes to a cross shape when positioned over a
- Use Parallel Direction
When off, all particles continuously
rotate to stay facing toward the Look At object. Each particle's
orientation varies because its location differs from those of the others.
When on, all particles face in the same direction, defined by an
imaginary line between the Particle Source gizmo center and the
Look At object. Default=off.
Use these settings to
specify the coordinate system for setting the size, as well as the
size parameters. The numeric settings in this group are not animatable.
- In World Space
Sets the absolute size
in system units, using the World coordinate system.
With the In World Space option,
sets the particle size in system units. Range=0 to 1000000000. Default=1.
- In Local Space
Sets particle size relative to
the existing size, in local space. Particle Flow uses the dimensions
of the existing shape to determine the size of the “facing rectangle.”
- Inherited %
Sets the facing particles' size
as a percentage of the existing size. Range=0 to 100. Default=100.
- In Screen Space
Sets the facing particles' size
as a percentage of the screen width. The actual size of each particle
changes as necessary throughout the animation, depending its distance
from the camera, to maintain a constant size from the camera's point
This option is available
only when the Look At object is a camera, and Use Parallel Direction
- Proportion %
Sets the particle size
as a percentage of the screen width. Default=1.
- Variation %
Sets the percentage by which
particle size can vary. Default=0.
- Pivot At
Specifies the part of
the particle around which rotation is performed when maintaining
the facing direction. The choices, available from the drop-down
list, are Top, Center, and Bottom. Default=Center.
With Top and Bottom,
the center of the corresponding side is used as the particle center for
This option is useful,
for example, when particles are lying on a surface, and each particle
is an explosion. In this situation, you'd probably want the entire
particle rectangle to appear above the surface, so you'd set Pivot
At to Bottom.
- W/H Ratio
Defines the aspect (width-to-height)
ratio of the shape rectangle.
Adjust this ratio to
that of the particle-map imagery. For the commonly used TV aspect ratio
of 4:3, set W/H Ratio=1.33. The parameter is not animatable. Range=0.001
to 1000. Default=1 (square particles).
This value is not animatable.
Use this drop-down list
to choose how particles rotate on the axes not specified by the
Look At direction. Default=Align to Horizon.
- Align to Horizon
Keeps the top edge aligned
with the horizon (the world XY plane).
- Align to Speed Follow
Uses the right side of each
particle as the leading edge, so the top and bottom edges are aligned
with the direction of particle motion.
Orients the top edge
- Allow Spinning
To spin the particles, choose
this option, and in the same event use a
operator. In the latter, set Rotation
Axis to Particle Space and use the default axis values: X=0, Y=0
The Uniqueness setting
enables changing the randomization of the size/width variation.
Specifies a randomization value.
Calculates a new seed using
a randomization formula.