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Size group
Use these settings to specify the coordinate system for setting the size of the
mark, as well as the size parameters. The numeric settings in this group are
not animatable.
In World Space Sets the absolute size of the mark in system units, using the
World coordinate system.
Width/Length With the In World Space option, sets the particle dimensions
in system units. Range=0 to 1000000000. Default=1.0.
In Local Space Sets the mark size relative to the existing particle size, in local
space. The software uses the dimensions of the existing shape to determine
the size of the “facing rectangle.”
Inherited % 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 the Length value of the mark
according to the 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) Max % Sets the maximum percentage by which the software
may stretch the mark. Available only when Impact Angle Distortion is on.
Default=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=Rectangle.
Rectangle The mark shape is a two-faced rectangle.
When using a material with 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.
2916 | Chapter 14 Space Warps and Particle Systems