Particle Effects – Arma 3

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)
• possibility 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 See also part).

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 only used when the the particle quality option [[particlesQuality]] in user settings matches this qualityLevel.
									// -1 play everytime, 0 play only on low, 1 play only on normal, 2 play only on high. Default: -1

		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
	};
};

Parameters simulation, type, qualityLevel, enabled, smokeGenMinDist, smokeGenMaxDist, smokeSizeCoef and smokeIntervalCoef are used everytime. Using 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 SomeClass
{
	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;				// How many rows there are in the texture. For example Universal is 16x16, so particleFSNtieth is 16. Default: 1
	particleFSIndex = 12;				// Row index 0 based, so particleFSIndex 12 will mean 13th row from the top. Default: 0
	particleFSFrameCount = 8;			// How many frames from the start of the chosen row to animate (particleFSFrameCount 8 means animate frames 1,2,3,4,5,6 and 7 in sequence). Default: 1
	particleFSLoop = 1;					// Whether or not to repeat from the beginning when all frames got played (0 - false, 1 - true). If particleFSLoop is 0 animation sequence is played only once. Default: 1
	animationSpeed[] = {3,2,1};			// interpolated speed of animation in animation cycles per second.
										// e.g if particleFSFrameCount is 8 and animationSpeed at the time is 0.4 result in 8 * 0.5 = 4 frame changes per second.
										// Value 1000 is a special value but only when combined with particleFSLoop 0;
										// this will instruct the engine to play only the last frame of the given count, so if particleFSFrameCount is 5, animationSpeed[] is {1000} and particleFSLoop is 0 only 5th frame will be played.

	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)
	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
	ignoreWind = false;							// if true, wind will not be applied on the 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
	destroyOnWaterSurface = 0;					// if particle should die if it went through water surface
	destroyOnWaterSurfaceOffset = -0.6;			// offset for _destroyOnWaterSurface parameter (it moves water surface when checking for intersection), 
	destroyAfterCrossing = false;				// if true, destroy when the whole particle is on the other side of the water surface. Only when _destroyOnWaterSurfaceOffset is enabled, 
	emissiveColor[] = {{30,30,30,0},{0,0,0,0}};	// sets emissivity of particle, 4th number has no meaning for now

	// --- fire damage related parameters (optional)
	damageType="Fire";					// damage type, only available option is "Fire" so far
	coreIntensity = 1.25;				// damage coeficient in the center of fire
	coreDistance = 3.0;					// how far can unit get damage
	damageTime = 0.1;					// how often is unit getting damage 

	// --- override of global particle quality params
	// --- current values are in, for example:
	// --- getNumber (((configFile >> "CfgVideoOptions" >> "Particles") select particlesQuality) >> "smokeGenMinDist");
	smokeGenMinDist = 100;				// for more info see "Changes dependent on distance"
	smokeGenMaxDist = 500;				// for more info see "Changes dependent on distance"
	smokeSizeCoef = 2.0;				// for more info see "Changes dependent on distance"
	smokeIntervalCoef = 4.0;			// for more info see "Changes dependent on distance"
};

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.

⚠

All [x,y,z] values have y and z swapped and are {x,z,y} when used in config

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 don'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 have a significant impact on performance and this helps to get better performance, so be careful with any change in the parameters below.

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 below).

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]];

ⓘ

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 (dynamic 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)
  • variables used in definition of part-effect are evaluated when the emitter is created - they are the same during its entire life
  • parameters ending with "Coef" in definition of part-effect are NOT evaluated
• 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

See the list of config parameters for more information.

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;

• in scripted particle effect set the first item in the ParticleArray (used by script command setParticleParams or drop) to:

["\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.

See also

Definition of an effect in a script:

• ParticleArray
• ParticleTemplates