Client API. The Codename One framework your app is built on: this runs on the device, not in a backend.

public class ParticleEmitter

Object
ParticleEmitter

Camera facing particles for 3D effects: explosions, sparks, dust, magic. Every particle of an emitter is drawn in one call as a soft round billboard that brightens in, fades out and changes size over its life.

An emitter is a pool of at most maxParticles live particles. burst spawns a batch at a point; update moves them and turns them toward the camera. Add it to a view with addTo(GameView) and keep it for the life of the scene – an emitter with no live particles draws nothing visible.

import com.codename1.gaming.*;
import com.codename1.gpu.*;
import com.codename1.ui.*;
import com.codename1.ui.layouts.BorderLayout;

class Campfire extends GameView {
    private ParticleEmitter fire;

    protected void onSetup(GraphicsDevice device) {
        fire = new ParticleEmitter(device, 64)
                .setColor(0xffff8a2a).setAdditive(true)
                .setSpeed(1.5f, 4f).setLifetime(0.3f, 0.7f).setSize(0.6f, 1.6f)
                .setGravity(-2f);
        fire.addTo(this);
    }

    protected void update(double deltaSeconds) {
        if (fire != null) {
            fire.burst(0f, 0.5f, 0f, 2);
            fire.update((float) deltaSeconds, getCamera());
        }
    }
}

Form f = new Form("Campfire", new BorderLayout());
f.add(BorderLayout.CENTER, new Campfire());
f.show();

Additive emitters suit light (fire, sparks, magic); alpha blended ones suit matter (smoke, dust, debris).

Constructors

public ParticleEmitter(GraphicsDevice device, int maxParticles) Creates an emitter able to hold maxParticles live particles.

Methods

`public` `Model getModel()`	The model that draws the particles.
`public void addTo(GameView view)`	Adds the emitter to `view`.
`public void removeFrom(GameView view)`	Removes the emitter from `view`.
`public` `ParticleEmitter setColor(int argb)`	Sets the particle color.
`public` `ParticleEmitter setAdditive(boolean additive)`	True to add light (fire, sparks), false to alpha blend (smoke, dust).
`public` `ParticleEmitter setSpeed(float min, float max)`	The initial speed range in world units per second.
`public` `ParticleEmitter setLifetime(float min, float max)`	The lifetime range in seconds.
`public` `ParticleEmitter setSize(float start, float end)`	The billboard size at birth and at death, in world units.
`public` `ParticleEmitter setGravity(float gravity)`	Acceleration along y in units per second squared; negative falls, positive rises (smoke, embers).
`public` `ParticleEmitter setDrag(float drag)`	The fraction of velocity lost per second.
`public` `ParticleEmitter setDirection(float x, float y, float z, float coneDegrees)`	Emits within `coneDegrees` of the direction `(x, y, z)`; 180 is every direction, 0 a straight jet.
`public int getLiveCount()`	The number of live particles.
`public boolean isActive()`	True while any particle is alive.
`public void clear()`	Removes every live particle.
`public void burst(float x, float y, float z, int count)`	Spawns `count` particles at `(x, y, z)`.
`public void update(float deltaSeconds,` `GameCamera camera)`	Moves the particles by `deltaSeconds`, retires the expired ones and turns the rest toward `camera`.

Inherited methods

From Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait, clone, finalize

Constructor details

ParticleEmitter

public ParticleEmitter(GraphicsDevice device, int maxParticles)

Creates an emitter able to hold maxParticles live particles.

Parameters

device GraphicsDevice: the device that will draw it; uploads the particle texture
maxParticles int: the pool size; a burst beyond it reuses the oldest

Method details

getModel

public Model getModel()

The model that draws the particles.

addTo

public void addTo(GameView view)

Adds the emitter to view.

removeFrom

public void removeFrom(GameView view)

Removes the emitter from view.

setColor

public ParticleEmitter setColor(int argb)

Sets the particle color. The alpha channel scales the whole effect.

setAdditive

public ParticleEmitter setAdditive(boolean additive)

True to add light (fire, sparks), false to alpha blend (smoke, dust).

setSpeed

public ParticleEmitter setSpeed(float min, float max)

The initial speed range in world units per second.

setLifetime

public ParticleEmitter setLifetime(float min, float max)

The lifetime range in seconds.

setSize

public ParticleEmitter setSize(float start, float end)

The billboard size at birth and at death, in world units.

setGravity

public ParticleEmitter setGravity(float gravity)

Acceleration along y in units per second squared; negative falls, positive rises (smoke, embers).

setDrag

public ParticleEmitter setDrag(float drag)

The fraction of velocity lost per second.

setDirection

public ParticleEmitter setDirection(float x, float y, float z, float coneDegrees)

Emits within coneDegrees of the direction (x, y, z); 180 is every direction, 0 a straight jet.

getLiveCount

public int getLiveCount()

The number of live particles.

isActive

public boolean isActive()

True while any particle is alive.

clear

public void clear()

Removes every live particle.

burst

public void burst(float x, float y, float z, int count)

Spawns count particles at (x, y, z). When the pool is full the oldest particles are replaced.

update

public void update(float deltaSeconds, GameCamera camera)

Moves the particles by deltaSeconds, retires the expired ones and turns the rest toward camera.