9

Shape Mark Operator 185
• Par ticle X/Y/Z—The Length direction is
parallel to the projec t ion of the part icle’s local
coordinate axis X, Y, or Z, respectiv ely, as the
particle moves toward the contact object.
•
Random—Uses a random Length direction in
the contact plane.
Divergence—Applies a range of random variation,
in degrees, to the orientation of the Length
direction. Unavailable when using the Random
option.
Size group
Use these settings to specify the coordinate system
forsettingthesizeofthemark,aswellasthesize
parameters. The numeric settings in this group
are not animatable.
In World Space—Sets the abs olute size of the mark
in system units, using the World coordinate
system.
Width/Length—With the In World Space opt ion,
sets the particle dimensions in system units.
Range=0 to 1000000000. Default=1.0.
In Loca l S pace—Setsthemarksizerelativetothe
existing particle size, in local space. The software
uses the dimensions of the existing shape to
determinethesizeofthe“facingrectangle.”
Inher ited %—Sets the percentage of the mark size,
relative to the existing particle size. Range=0 to
100. Default=100.0.
Variation % —Sets the percentage by which particle
size can vary. Default=0.0.
Impact Angle Distortion—When on, increases
theLengthvalueofthemarkaccordingtothe
particle’s angle of approach. This effectively
stretches the mark shape if particle approaches the
contact geometry at a low angle. Available only
when Align To is set to Speed. Default=off.
For example, if a drop of paint hits a surface
perpendicularly, it creates a circular mark, but if
it hits the surface at a lower angle, the resulting
shape is an ellipse.
Distor(tion) M ax % —Sets the maximum percent age
by which the software may stretch the mark.
Available only when Impact Angle Distortion is
on. D efault=1000.
With very low angles of approach, the stretching
factor can become very high. For example, value
500% means that the stretching factor cannot
exceed 5.
Shape group
These settings let you specify the mark-making
object as a rectangle or a box. Default=Rec tang le.
Rectangle—The mark shape is a two-faced
rectangle.
When using a material w ith Shape Mark, always
choose this option.
Box Intersection—With this option, the software
creates a box for each particle that leaves a mark,
and derives the mark shape from a Boolean
intersection between the contact object and the
box.
Box Height—Sets the height of the box used w ith
the Box Intersection method . Available only with
Box Intersec tion. Default=10.0.
Allow Multiple Elements—When on, particles can
leave marks on all parts of contact objects that
contain multiple elements. When off, a particle
marksonlythefirstelementitcollideswith.
Available only with Box Intersection. Default=off.