Particle Effects – Arma 3

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Intro

Please be aware of our Arma 3 Modding License.

Related links

Definition of an effect in a script:


Definition of effect

There are two ways how to define particle effect in Arma 3 - script and config. Pros and cons of config defined effects:

  • difficult editing (every change in any parameter requires restart of the game)
  • posibility to change the effect outside of the effect's definition is limited
  • more parameters (some advanced parameters are present only in config)
  • better performance (this is not true for each effect)
  • calling of an effect can be used in a specific engine-supported parameter

Technology of scripted effects is older and the documentation is already present on wiki (see Related links).

Config

Each complex effect (CE) is created by part-effects (PE) (defined in CfgCloudlets) and light (defined in CfgLights).

Definition of complex effect

Class of CE is defined directly in configFile and consists of classes that link PE (or light) to the parent effect. 

class ComplexEffect
{
   class Example1
   {
       simulation = "particles";   //type of simulation - particles or light
       type = "Default";           //name of PE's class defined in CfgCloudlets or light's class defined in CfgLights
       position[] = {0, 0, 0};     //position related to the default position or memorypoint
       lifeTime = 0.05;            //life time of emitter
 
       qualityLevel = -1;          //effect is used when the particle quality option is -> -1 everytime, 0 low, 1 normal, 2 high
       start = 1;                  //is used only if the lifeTime parameter is defined, if value is changed from negative to positive then the effect is triggered
       enabled = 1;                //1 effect is enabled, -1 effect is disabled

       smokeGenMinDist = 100;      //for more info see part Changes dependent on distance
       smokeGenMaxDist = 500;      //for more info see part Changes dependent on distance
       smokeSizeCoef = 2.0;        //for more info see part Changes dependent on distance
       smokeIntervalCoef = 4.0;    //for more info see part Changes dependent on distance
   };
};

Parameters simulation, type, qualityLevel, enabled, smokeGenMinDist, smokeGenMaxDist, smokeSizeCoef and smokeIntervalCoef are used everytime. Using of other parameters depends on calling of the effect (see Calling of effect).

Definition of part-effect

Class of PE must be in configFile class CfgCloudlets. 

class Default
{
    interval = "0.5 * speedSize + 0.5";      //interval of particle's creation
    circleRadius = 0;			     //radius around emitter where particles are created
    circleVelocity[] = {0, 0, 0};	     //direction and speed of movement of particle's circle
    particleShape = \A3\data_f\ParticleEffects\Universal\Universal;		//path and name of file
    particleFSNtieth = 16;		     //coef; size of one particle's texture in pixels = 2048/coef
    particleFSIndex = 12;		     //index of start line on texture
    particleFSFrameCount = 8;		     //count of pictures in animation (starts on first picture in defined line - particleFSIndex)
    particleFSLoop = 1;		             //loop of animation (0 - false, 1 - true)
    angle = 0;				     //angle of particle
    angleVar = 0;			     //variability in angle of particle

    animationName = "";
    particleType = "Billboard";	             //type of animation (Billboard (2D), Spaceobject (3D))
    timerPeriod = 1;			     //interval of timer (how often is called script defined in parameter onTimerScript)
    lifeTime = 1;			     //life time of particle in seconds
    moveVelocity[] = {0, 0, 0};	             //direction and speed of movement of particle [x,z,y]
    rotationVelocity = 0;		     //direction and speed of rotation of particle [x,z,y]
    weight = 1;			             //weight of particle (kg)
    volume = 1;			             //volume of particle (m3)
    rubbing = 0.05;			     //how much is particle affected by wind/air resistance
    size[] = {1,1};			     //size of particle during the life
    color[] = {{1,1,1,1},{1,1,1,0}};	     //color of particle during the life (r,g,b,a)
    animationSpeed[] = {1};		     //speed of animation (number of animation cycles in 1s)
    randomDirectionPeriod = 0;		     //interval of random speed change
    randomDirectionIntensity = 0;	     //intensity of random speed change
    onTimerScript = "";		             //script triggered by timer (in variable "this" is stored position of particle)
    beforeDestroyScript = "";		     //script triggered before destroying of particle (in variable "this" is stored position of particle)
    lifeTimeVar = 0;			     //variability in lifetime of particle
    position[] = {0, 0, 0}                   //defines position of effect
    positionVar[] = {0, 0, 0};		     //variability in position of particle (each part of vector has it's own variability)
    positionVarConst[] = {0, 0, 0};	     //variability in position of particle (variablity of all parts of vector is the same)
    moveVelocityVar[] = {0, 0, 0};	     //variability in direction and speed of particle (each part of vector has it's own variability)
    moveVelocityVarConst[] = {0, 0, 0};      //variability in direction and speed of particle (variablity of all parts of vector is the same)
    rotationVelocityVar = 0;		     //variability in rotation of particle
    sizeVar = 0;			     //variability in size of particle
    colorVar[] = {0, 0, 0, 0};		     //variability in color of particle
    randomDirectionPeriodVar = 0;	     //variability in interval of random speed change
    randomDirectionIntensityVar = 0;	     //variability in intensity of random speed change
    sizeCoef = 1;                            //size of particle = size parameter value * this coef (works only in some effects)
    colorCoef[]={1,1,1,1};                   //color of particle = color parameter value * this coef (works only in some effects)
    animationSpeedCoef = 1;                  //animation speed of particle = animationSpeed parameter value * this coef (works only in some effects)

    destroyOnWaterSurface = 0;               //particle can exist - only underwater (-1), only above the water (1), everywhere (0)
    destroyOnWaterSurfaceOffset = 0;         //offset of water surface in destroyOnWaterSurface parameter
    onSurface = true;                        //placing of particle on (water) surface on start of it's existence, default value is true, works only if circleRadius > 0
    keepOnSurface = false;                   //true for particle is stay on water surface - see notes bellow
    surfaceOffset = 0;                       //offset of water surface in keepOnSurface parameter
    bounceOnSurface = 0.6;                   //coef of speed's loosing in collision with ground, 0-1 for collisions, -1 disable collision
    bounceOnSurfaceVar = 0.0;                //variability in speed's loosing in collision with ground
    postEffects = "IEDMineFlame";            //effect triggered before destroying of particle
    particleEffects = "ExplosionShardsFire"; //emitter of effect defined in this parameter is attached to each particle
    blockAIVisibility = true;                //sets if particles are in the AI visibility tests (default true) - false for better performance but AI is able to see through particles
    emissiveColor = {{30,30,30,0},{0,0,0,0}} //sets emissivity of particle, 4th number has no meaning for now
};

Notes:

  • Ascent/descent of a particle is affected by ratio bewteeen particle's density (weight/volume) and density of air (it's 1.275 kg/m3 in Arma).
  • Parameters ending with "Coef" are used only in some effects, see info about Config parameters.
  • Only 3D particles (particleType = "SpaceObject") can use materials.
  • You can use single frame in middle of line on texture as texture of particle. Just set particleFSLoop = 0 and animationSpeed[] = {1000}, then paremeter particleFSFrameCount is number of frame in given line.

Evaluation in definition of part-effect

There can be inserted string instead of number in most of parameters used in definition of part-effect. This string is evaluated and in this string can be used engine-defined variables from this list.
List of parameters which doesn't support this type of evaluation: 

particleShape
particleFSNtieth
particleFSIndex
particleFSFrameCount
particleFSLoop
angleVar
animationName
particleType
color
onTimerScript
beforeDestroyScript
sizeVar
destroyOnWaterSurface
destroyOnWaterSurfaceOffset
onSurface
keepOnSurface
surfaceOffset
bounceOnSurface
bounceOnSurfaceVar
postEffects
particleEffects

Operators which can be used in evaluated strings: Simple Expression

Behaviour of particles

Speed of rotation depends on

  • initial rotation speed (parameters rotationVelocity and rotationVelocityVar)
  • air friction (rotation is slowed more with bigger value of rubbing, rotation is slowed less with bigger value of weight)

Speed and direction of movement depends on

  • initial speed of movement (parameters moveVelocity, moveVelocityVar and moveVelocityVarConst)
  • wind/air friction (particle is more affected with bigger rubbing value, particle is less affected with bigger weight value)
  • buoyancy (ratio between density of air and particle - density of particle = weight / volume)
  • randomDirection parameters (randomDirectionPeriod, randomDirectionPeriodVar, randomDirectionIntensity and randomDirectionIntensityVar)
  • collisions

Changes dependent on distance

Particles are simplified with bigger distance between particles and observer. Particles has significant impact on performance and this helps to get better performance, so be carefull with any change in parameters bellow.

Parameters:

  • smokeGenMinDist - defined in Definition of complex effect, default values in config class CfgDefaultSettings
  • smokeGenMaxDist - defined in Definition of complex effect, default values in config class CfgDefaultSettings
  • smokeSizeCoef - defined in Definition of complex effect, default values in config class CfgDefaultSettings
  • smokeIntervalCoef - defined in Definition of complex effect, default values in config class CfgDefaultSettings
  • dist - distance between camera and particle emitter, cut to interval <smokeGenMinDist, smokeGenMaxDist>
  • currentZoom - zoom currently used
  • smokeZoomCoef - defined in config class CfgDefaultSettings


Calculations:

  • distCoef = (dist - smokeGenMinDist)/(smokeGenMaxDist - smokeGenMinDist)
  • coef = distCoef * currentZoom * smokeZoomCoef
    • coef is cut to interval <0,1>
  • sizeCoef = 1.0 + coef * (smokeSizeCoef - 1.0)
  • intervalCoef = 1.0 + coef * (smokeIntervalCoef - 1.0)


Changes in particles are made according to these coef values:

  • sizeCoef - size of particle is multiplied by this value
    • value is cut to interval <1, smokeSizeCoef>
  • IntervalCoef - interval (how often is particle created by emitter) is multiplied by this value
    • value is cut to interval <1, smokeIntervalCoef>



Calling of effect

There are two ways how to call a particle effect defined in config. You can use script or one of the engine-provided config parameters. Using of a config parameter (if there is one you can use) is usually recommended, because of better performance and an efficient use of engine-provided variables in PE definitions (see the list bellow).

Script

There is script command setParticleClass. This command can use only a class of PE.
Example: 

_source01 = "#particlesource" createVehicleLocal _pos01;
_source01 setParticleClass "ObjectDestructionFire1Smallx";
_source01 attachto [_object,[0,0,0]];


Tip: You can use this way of particle definition and then overwrite some parameters by script command setParticleParams. This way you can get some pros of config-defined (access to parameters which are not present in ParticleArray) and scripted (dynamical changes of parameters in script) effects at once.

Config parameters

These engine-provided parameters have already set conditions for using of particle effect. For example parameter for exhaust effect is triggered when the engine of vehicle is running. Each parameter has engine-provided variables which can be used in some parts of definition of particle effect.

There are two types of emitter when you call an effect via config parameter. The type of emitter is specified in the engine for each parameter and behaviour of each emitter type is different:

  • constant emitter (CE)
  • real-time emitter (RE)
    • variables in definition of part-effect are evaluated for each single particle
      (it's each frame actually - if you create more than one particle in single frame, then variables are the same for all these particles)
    • parameters ending with "Coef" in definition of part-effect ARE evaluated


For more info see List of config parameters.

Specials

Refraction (heat) effect

You can create refraction effect which simulates movement of hot air (around exhausts, fires, etc.). There is special texture for this purpose.

How to create refract effect:

  • in config-defined particle effect set:
particleShape = \A3\data_f\ParticleEffects\Universal\Refract;
particleFSNtieth = 1;
particleFSIndex = 0;
particleFSFrameCount = 1;
particleFSLoop = 0;

["\A3\data_f\ParticleEffects\Universal\Refract",1,0,1]

Important notes:

  • First three items (RGB) in color array have no meaning with refract effect, last item (alpha) defines refraction index (basically visibility of effect).
  • All other parameters have the same meaning as in any other particle effect.
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