Building your own effect

Under Advanced you can stack behaviours onto an effect. Each one answers a single question about the particles — how they fade, how big they are, which way they go, where they start — and together they make the effect.

What each behaviour does

Over a particle’s life

Fade over life — opacity changes as the particle ages. Add points to the list for fade-in-then-out.
Grow or shrink — size changes as it ages. Smoke swells, sparks shrink.
Colour over life — shifts from one colour to another. This is the one that sells fire.
Speed over life — speeds up or slows down as it ages.

Fixed for each particle

Constant opacity, Constant size, Constant speed, Single colour — each particle picks a value in a range and keeps it.

Movement

Travel direction — the angle each particle sets off in. 270 is up.
Direction & spin — a starting direction plus a turn rate, so particles curve as they fly.
Gravity & acceleration — a starting speed plus a constant pull. Positive Y pulls down the map; this is what makes a fountain arc.
Lock rotation — holds every particle at one angle regardless of travel.

Where and how they appear

Spawn from a point, Spawn area (circle, ring, box or a drawn shape), Spawn burst (evenly spaced spokes).
Blend mode — how particles mix with the map.

Adding a behaviour that’s already on the effect isn’t possible — there’s one of each. Remove one from inside its panel.

Worked example: dust falling from a ceiling

Place Dust motes and open Advanced.
On Travel direction, set the range to 80–100 so everything drifts down.
On Constant speed, set 30–70 so the specks fall at different rates.
Add Fade over life so they appear and vanish rather than popping.
On Spawn area, choose a box and widen it to the room.
Back on Amount, drop Intensity until it reads as a trickle of grit, not a sandstorm.

Following a shape you’ve drawn

Set Spawn area to a drawn shape and the panel asks you to click one of the scene’s spaces on the map. Particles then appear along that outline — that’s how Flame wall puts fire along a barricade. Spaces come from your walls and drawn shapes; see keeping effects in a space.

Keeping the table smooth

Effects are drawn on every player’s machine, so a heavy scene costs the person with the oldest laptop the most.

Watch Intensity first — it’s the biggest lever on cost.
Under Emitter internals, Most particles at once is a hard ceiling; thousands of long-lived particles will cost frames.
Long particle lifetime plus fast spawning is the expensive combination.
Two or three effects usually read better than eight, and cost far less.

Tuning an effect — the simple controls first.
The effect library — better starting points.
Building the map — the rest of the map tools.