[ < ] | [ Up ] | [ > ] |  |  |  |  |  |  |  | [Top] | [Contents] | [Index] | [ ? ]

### 3.2.3 Particle Emitter Attributes

This section describes the common attributes of all particle emitters. Specific emitter types may also support their own extra attributes.

### angle

Sets the maximum angle (in degrees) which emitted particles may deviate from the direction of the emitter (see direction). Setting this to 10 allows particles to deviate up to 10 degrees in any direction away from the emitter's direction. A value of 180 means emit in any direction, whilst 0 means emit always exactly in the direction of the emitter.

format: angle <degrees>
example: angle 30
default: 0

### colour

Sets a static colour for all particle emitted. Also see the colour_range_start and colour_range_end attributes for setting a range of colours. The format of the colour parameter is "r g b a", where each component is a value from 0 to 1, and the alpha value is optional (assumes 1 if not specified).

format: colour <r> <g> <b> [<a>]
example: colour 1 0 0 1
default: 1 1 1 1

### colour_range_start & colour_range_end

As the 'colour' attribute, except these 2 attributes must be specified together, and indicate the range of colours available to emitted particles. The actual colour will be randomly chosen between these 2 values.

format: as colour
example (generates random colours between red and blue):
colour_range_start 1 0 0
colour_range_end 0 0 1
default: both 1 1 1 1

### direction

Sets the direction of the emitter. This is relative to the SceneNode which the particle system is attached to, meaning that as with other movable objects changing the orientation of the node will also move the emitter.

format: direction <x> <y> <z>
example: direction 0 1 0
default: 1 0 0

### emission_rate

Sets how many particles per second should be emitted. The specific emitter does not have to emit these in a continuous burst - this is a relative parameter and the emitter may choose to emit all of the second's worth of particles every half-second for example, the behaviour depends on the emitter. The emission rate will also be limited by the particle system's 'quota' setting.

format: emission_rate <particles_per_second>
example: emission_rate 50
default: 10

### position

Sets the position of the emitter relative to the SceneNode the particle system is attached to.

format: position <x> <y> <z>
example: position 10 0 40
default: 0 0 0

### velocity

Sets a constant velocity for all particles at emission time. See also the velocity_min and velocity_max attributes which allow you to set a range of velocities instead of a fixed one.

format: velocity <world_units_per_second>
example: velocity 100
default: 1

### velocity_min & velocity_max

As 'velocity' except these attributes set a velocity range and each particle is emitted with a random velocity within this range.

format: as velocity
example:
velocity_min 50
velocity_max 100
default: both 1

### time_to_live

Sets the number of seconds each particle will 'live' for before being destroyed. NB it is possible for particle affectors to alter this in flight, but this is the value given to particles on emission. See also the time_to_live_min and time_to_live_max attributes which let you set a lifetime range instead of a fixed one.

format: time_to_live <seconds>
example: time_to_live 10
default: 5

### time_to_live_min & time_to_live_max

As time_to_live, except this sets a range of lifetimes and each particle gets a random value inbetween on emission.

format: as time_to_live
example:
time_to_live_min 2
time_to_live_max 5
default: both 5

### common_direction

Only required if billboard_type is set to oriented_common, this vector is the common direction vector used to orient all particles in the system.
format: common_direction <x> <y> <z>
example: common_direction 0 -1 0
default: none

See also: 3.2.4 Standard Particle Emitters, 3.2 Particle Scripts, 3.2.5 Particle Affectors

[ < ] | [ Up ] | [ > ] |  |  |  |  |  |  |  | [Top] | [Contents] | [Index] | [ ? ]

This document was generated by Steve Streeting on , 28 2004 using texi2html