Emitters

Emitters

An emitter is built with Vfx.emitter() and finished with play(level, pos). It starts from the default burst, so you override only what you need. This page walks the main groups of settings; the full list is in the VfxEmitter javadoc.

Shape and count

The spawn volume comes from ShapeSpec: point, line, ring, sphere, cone, box, disc, or hemisphere. Sizes are in blocks.

Vfx.emitter()
        .shape(ShapeSpec.cone(1.5f, 2f))
        .count(120)     // particles in a burst
        .lifetime(60)   // ticks each particle lives
        .speed(0.15f)   // initial speed
        .play(level, pos);

For a steady stream instead of a one-shot burst, use rate:

.rate(4f, 40) // 4 particles per tick for 40 ticks; count is then ignored

Appearance

Size, alpha, and color are curves over a particle's life, eased by an Easings value. Color can be a two-stop fade or a multi-stop gradient.

.size(0.25f, 0f, Easings.EASE_OUT_QUAD)   // start, end, ease
.alpha(1f, 0f, Easings.LINEAR)
.gradient(Easings.LINEAR, 0xFFE9A8, 0xB84DFF, 0x3A2C86)

Pick the atlas sprite and blend, and layer on optional looks:

.sprite(SpriteId.SMOKE)   // GLOW, SMOKE, SPARK, RING, STAR, SHARD
.blend(BlendMode.ALPHA)   // ADDITIVE glows, ALPHA occludes
.lit()                    // read world light instead of drawing full bright
.soft()                   // fade against scene geometry (alpha blend only)
.animate()                // play the sprite's frames across the life
.stretch(1.5f)            // streak fast particles along their velocity
.spin(0.2f)               // random roll plus a per-tick spin
.trail(5)                 // ribbon through the last 5 positions

Motion

By default particles fire radially outward. The other velocity modes:

.implode()               // inward toward the shape center
.orbit()                 // tangent to the vertical axis, a swirl
.jet(0f, 1f, 0f, 0.3f)   // a cone along a direction, half-angle in radians

Layer on forces (gravity, curl noise, vortices, flocking) as described in Forces and Steering.

Meshes

Instead of billboards, particles can be solid geometry. Meshes are opaque and fade by shrinking their size curve rather than by alpha, so pair them with a spin.

.cube()                // tumbling solid box
.shard()               // elongated splinter
.block(Blocks.STONE)   // a real block model, for break debris
.item(Items.DIAMOND)   // a real item model

Collision and sub-emitters

Particles can bounce off blocks and spawn child systems on death or impact:

.collide(0.4f, 0.2f)                         // bounce, friction
.burstOnDeath(Vfx.emitter().count(20))       // child fires where a particle dies
.burstOnCollision(Vfx.emitter().count(10))   // child fires on first block contact

Layering

Combine several emitters into one effect played at a single point:

Vfx.effect()
        .add(Vfx.emitter().shape(ShapeSpec.sphere(0.4f)).count(300))
        .add(Vfx.emitter().shape(ShapeSpec.sphere(1.7f)).count(160).lit())
        .play(level, pos);