Particles
Parameters
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Parameters are used to change the behavior of a particle system. Examples of
dynamic parameters are: gravity, radius, startspeed, etc.
To change the parameters, first select the particles using get solid tag.
To change the parameters for a group of particle systems, select the top tag of the group.
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Upon selecting a parameter from the parameter selection list (by clicking twice on the parameter name), a parameter box will appear on screen. All parameter boxes have mean and variance input boxes where values can either be inputted by using the scroll wheel or step boxes, or they can be typed in.
- mean is used to set the actual value of the parameter.
- variance adds a random effect based on the mean.
For example, a mean of 10 and a variance of 5 will result in random values between 5 and 15. A mean of 10 and a variance of 0.0 indicates no random behavior because there is no variance in the parameter (it is always 10).
The following parameters are available in the scroll list just below the get solid tag button:
- blur
- This parameter allows you to scale the length of the particles. When the blur is non zero and the particles are moving, they will have a head (at the front) and a tail.
Particles with blur 0.0 will have no tail. The effect of blur can be seen when rendering or when show radius is active.
blur: 0.0 
0.5 
1.0 
- fluid
- This parameter allows you to control the total influence of all the fields assigned to the particles as fluid fields .
It is to be used only when fields have been assigned to fluid fields
- force
- This parameter allows you to control the total influence of all the fields assigned to the particles as force fields.
It is to be used only when fields have been assigned to force fields.
- friction
- This parameter allows you to set the friction with a collision tag model when particles collide.
The higher the friction, the faster the velocity of particles will drop off in the direction along the surface. When friction is 0.0, particles will continue to move along the surface at collision.
friction: 0.1 
0.3 
- gravity
- This parameter allows you to change the effect of gravity on particles.
- grow
- This parameter allows you to increase or decrease the radius of the particles during their lifetime in steps of 100 frames. Therefore a grow of 1.0 results in an increase in radius of 1.0 after a particle has lived for a 100 frames.
grow: 0.0 
1.0 
-1.0 
- lifetime
- This parameter allows you to set the lifetime duration of emitted particles in frames.
A lifetime of 10 means that each particle will live for only 10 frames and then die (disappear).
- mass
- This parameter allows you to change the mass of the material of a particle relative to its radius. Mass and radius together determine the actual mass of a particle. Thus a particle with radius 1.0 has a larger mass than a particle with a radius 0.2, even if their mass parameter is the same.
- pulseoffset
- This parameter allows you to set the offset for the pulsetime. If the offset is 0, the particles are emitted at frame 1; if set to 10, the first emission will start at the 11th frame.
- pulsetime
- This parameter allows you to set pulsetime intervals in frames. If the pulsetime is 10, particles are emitted every 10 frames.
Setting the pulsetime below 1 will emit more particles during every frame. For example, a pulsetime of 0.5 will emit two particles every frame. However, to actually see two different particles, this should be used in conjunction with a random startangle.
- radius
- This parameter allows you to change the size of the particles when they are emitted or generated.
Increasing the radius will increase the actual mass of the particles.
To actually see the radius of the particles, either they will have to be rendered or show radius switched on. The latter will result in a slower wireframe display.
- resilience
- This parameter allows you to change the bounce factor of particles when they collide with a collision tag model.
A resilience of 0.0 means no bounce; a resilience of 1.0 means a full bounce.
resilience: 0.0 
0.75 
0.9 
- startangle
- This parameter allows you to rotate the direction of particles around the z-axis away from their initial direction when they are emitted.
- startroll
- This parameter allows you to roll the initial direction of particles from their initial direction when they are emitted. Startroll has no visible effect if the startangle is zero.
- startspeed
- This parameter allows you to set the initial speed of particles when they are emitted.
- tailsize
- A particle has both a head and tail. Tailsize is used to set the size (radius) of the tail in relation to the radius of the head of a particle.
For example, a tailsize of 2 indicates a tail which is twice as large as the head.
- Note:
- If the blur is set to 0, a particle has no tail.
tailsize: 0.0 
1.0 
2.0 
- timestep
- This parameter allows you to set the rate at which time passes (the increments in time for each frame).
Increasing the timestep will increase the speed of the simulation.
- velocity
- This parameter allows you to control the total influence of all the fields assigned as velocity fields to the particles.
It is to be used only when fields have been assigned to velocity.
- viscosity
- This parameter allows you to set the viscosity for all the fields assigned as fluid fields to the particles.
It is to be used only when fields have been assigned to fluid fields.
- spring
- To set the stiffness of the springs when using dynamic splines or skins of Organic. A low value like 10.0 means loose springs, a high value like 400.0 means tight springs. Setting the springs too high can result in instable simulation. To prevent this, lower the value for timestep.
- damp
- To set the damping of the springs when using dynamic splines or skins of Organic. A low value like 0.0 means no damping, a value like 10.0 means the springs will be damped and come to rest sooner.
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- get parameters
- This button allows you to get saved parameter settings.
- save parameters
- This button allows you to save parameter settings.
- reset parameters
- This button allows you to reset all parameters for all particle systems of the current selected tag to their default values.
- record
- Parameters can be animated in time during simulation (for example, animating the gravity of the particles in time). See the chapter on Simulation and Record for an explanation.
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