Particles often move
at high rates of speed. In such cases, you might want to add motion
blur to the particles to enhance their motion. Also, real-world
particles typically rotate as they move, and collide with each other.
The options on this rollout
affect the rotation of the particles, provide motion blur effects,
and control inter-particle collisions.
Spin Speed Controls group
- Spin Time
The number of frames
for one rotation of a particle. If set to 0, no rotation takes place.
The percent of variation of
the Spin Time.
Sets the initial particle rotation,
in degrees. This has no meaning for fragments, which always begin
with zero rotation.
The percent of variation of
Spin Axis Controls group
These options determine
the spin axis for the particles, and provide a partial method of
applying motion blur to the particles.
The spin axis for each
of the particles is random.
- Direction of Travel/Mblur
(Not available with the Blizzard
particle system.) Rotates the particles about a vector formed by
the direction in which they're moving. This option also lets you
apply a form of motion blur to the particles by using the Stretch
spinner. For further information, see
Achieving Particle Motion Blur.
When greater than 0,
the particles stretch along the travel axis, depending on their
speed. Specifically, the Stretch value specifies the percent of
their length per each unit of the Speed setting (in the Particle
Motion group). Thus, if you set Stretch to 2 while Speed is set
at 10, the particles are stretched 20 percent longer than their
original size along the axis of their travel. This spinner is available
only when you choose Direction of Travel/Mblur.
NoteFor best results
when using Stretch, you should also assign the Particle MBlur map
as an opacity map of the material assigned to the particle system.
- User Defined
Uses a vector defined
in the three X, Y, and Z axis spinners.
- X/Y/Z Axis
Specifies the spin vector of
the X, Y, or Z axis, respectively. These spinners are available
only when User Defined is chosen.
The amount, in degrees, by
which the spin axis of each particle may vary from the specified
X Axis, Y Axis, and Z Axis settings. This spinner is available only
when you choose User Defined.
These options enable
collisions between particles, and control how the collisions occur.
Note that this involves intensive calculation, particularly when
large numbers of particles are involved.
Enables inter-particle collisions
in the calculation of the particle movements.
- Calc Intervals Per Frame
The number of intervals per
rendering interval, during which an inter-particle collision test
is conducted. The higher the value, the more accurate the simulation,
but the slower the simulation will run.
The degree to which speed
is recovered after a collision.
The percentage of random
variation of the Bounce value, applied to the particles.