Settings

This module gives access to most of the particle settings necessary to create particle effects.

Patterns

The first section has 4 buttons each of which activates a different pattern of particle emission:

  • The Drop pattern will emit particles which will remain stationary throughout their lives. They will however respond to some settings such as radius, size, alpha, glow and colour settings.
  • The Explode pattern sprays particles randomly in a spherical area around the emitter.
  • The Angle pattern sprays particles outwards from the emitter in straight lines. The angle of emission is set by the Burst Angle setting.
  • The Angle Cone pattern sprays particles outwards from the emitter in a conical or spherical pattern. Again, the angle of emission is set by the Burst Angle setting.

Target

Selecting the Target setting will display the Targets face where you can specify a target towards which particles will be aimed. There are 5 options:

  • Emitter: the emitter itself will become the target and all particles will return to the emitter at the end of their lives.
  • Remote: A remote prim will be rezzed and particles will be aimed at it.
  • Avatar: This allows you to direct particles at any avatar within range. A sub-menu listing nearby avatars will appear. Only the nearest 11 avatars will be displayed. If no avatars are within range, a message to that effect will appear in local chat.
  • User: This will direct particles at the User of the Emitter ie YOU!
  • No Target – self-explanatory.

Other Settings

When any of the other settings is selected, the relevant face will be displayed. Each setting has a maximum and minimum allowed value. These will be shown in the display. The current value for each parameter will also be displayed. If you enter a value which exceeds the allowed limits, the value will not be changed and a message to this effect will appear in local chat.

In every case, values are entered using the numbers section of the face. The same display is used for all settings. However, areas of the numeric display are greyed out where they are not relevant to the current setting. (See graphics below.)

Entering Values

Values are entered by clicking on the buttons which have a blue background. They are:

  • + and – buttons: These decide whether values are positive or negative. They only affect 2 settings: Omega and Accelerate. In both cases, negative values will reverse the direction of the particles.
  • Up triangle arrows: These increase the number directly below by 1 for each click. For example, if you click the up arrow immediately above the 5 in the x row, it will change to 6 and the new value will be 16.24.
  • Down triangle arrows: These decrease the number directly above by 1 for each click. For example, if you click the down arrow immediately below the 5 in the z row, it will change to 4 and the new value will be 1.42.
  • x, y, z: These are used to select which of the 3 values you will be adjusting. Some parameters only have one value, some have x and y values and only two, Omega and Accelerate, use all 3 values.

Clicks on any other areas will be ignored.

Start and End

Various settings can have a START and an END value. With some settings  (Alpha, Glow, Scale) this means that particles will gradually transition from the Start Value to the End Value during the lifetime of the particle. With Burst Angle and Speed, the Start and End values will be applied to alternate particles. In all cases, End = Start (E = S) will mean that there will be no transitions and no difference in Burst Angle or Speed.

  • Click START to select the Start setting.
  • Click END to select the End setting.
  • Click E = S  to ensure that START and END have the same value.

The Settings

The alpha setting is used to decide the transparency of the particle. A value of 1.0 has no transparency at all and the particle will be fully visible. A value of 0.0 is completely transparent. Setting a Start Value of 1.00 and an End Value of 0.0 means that particles will vanish gradually over their lives and will disappear subtly. Bear in mind that some particle textures (like the bubble textures) may themselves be semi-transparent.

Glow decides whether a particle will glow or not. Very small values (0.2 or less) will usually be most effective. It works in exactly the same way as the Alpha setting.

Scale determines the size of the particle. It ranges from a minimum value of 0.04 metres (VERY small!) to 4 metres. Start and End settings allow size to change from the Start value to the End value during the lifetime of the particle. In this case particles will appear to shrink or grow during their lifetime. You will notice that there is an ‘x/y’ setting and a ‘y’ setting. Changing the ‘x/y’ values will change both the x and y values together. This will work well with particles which are square. If you do wish to give them different values, set the ‘x/y’ setting first and then adjust the ‘y’ setting.

Radius decides how far from the emitter, particles will be emitted. For example, a value of 2.00 will result in particles being emitted 2 metres away from the emitter.

Burst Angle decides the angle at which particles are emitted. Start and End Values can be used to set different values so alternate particles will be emitted in different directions. Try it  with a Count of 2 to see how it works. This setting only has an effect with the Angle and Angle Cone patterns.

Speed can be used to set how fast (or how slowly) particles will travel when they are emitted. Again Start and End values can be used. Relatively small values (less than 10.00) are generally more effective.

Omega is used to spin particles on any or all of the 3 axes, x, y and z. This will only have an effect when the Angle or Angle Cone pattern is set. Nothing much will appear to happen unless you have set a very short Rate value such as 0.2 or less. (A more effective way to achieve the same effect is by rotating and spinning the emitter.)

Count decides the number of particles which will be emitted in each burst. Don’t be tempted to enter too high a number here or you will quickly run out of particles.

Rate is the gap between particle bursts so a smaller number will result in more frequent bursts and therefore more particles. A value of 0.0 results in a constant stream of particles.

Life determines how long a particle will exist. 30 seconds is the maximum lifetime of a particle. Very short life settings with star-like textures can produce very interesting sparkling results.

Duration decides how long the emitter will continue to produce particles. For example, a value of 5.00 means that particles will only be produced for 5 seconds after which the emitter will stop emitting particles. A value of 0.0 means particles will be emitted infinitely.

Accelerate will ‘push’ particles along the x, y and z axes. Even small values (less than 1.00) will have a very obvious effect. Negative values will reverse the direction of push.

Using the Settings

Try to avoid emitting more particles than you need for the effect you are trying to create. A quick calculation can give you a rough idea.

  • look at rate and calculate how many bursts there will be in 1 second. For example, if you have set a value of 0.02, there will be 50 bursts in a second.
  • multiply that by the value of Count. If this is 4, then there will be 200 new particles emitted every second.
  • multiply that by the number of seconds in the Life of the particle. If it is the maximum value of 30, then you would have 6000 particles existing concurrently.

That’s a LOT of particles and it can have an impact on performance so it makes sense to keep the number as low as possible!

It’s worth noting that the best effects will be created when you use settings in conjunction with each other. In some cases, a setting will have no effect if another setting is set in a particular way. For example, with the Drop pattern set, Speed, Burst Angle, Omega and Accelerate will have no effect whatsoever.

Great effects are possible when you use settings which appear to contradict each other. For example, if you set the Angle Pattern and a fast speed of say 3.0 r greater, then particles will be shot straight up in the air very quickly. BUT…. if you then apply downward acceleration, they will be pulled back down again in a graceful arc. If you have the Bounce flag ticked, they will then bounce when they reach the emitter height position and continue to do so for the life of the particle.