Particles

Makes this object solid to particles in a flat scene: sparks bounce off it and rain ends on it.

The shape is measured on the object, so it moves, turns and stretches with it. It only stops the effects whose file says how they collide; every other effect goes straight through, which is what smoke and glows want.

One per object. A staircase is one object per step, each with its own.

Makes this object solid to particles in three dimensions. The same thing as the flat one, with a box, a ball or an endless floor.

When and how many appear.

rate and burst are both here and they mean different things: rate is a fountain, so many a second for as long as it runs, and burst is an explosion, all of them the moment the cycle starts. An effect usually wants one and occasionally wants both, so neither can be said with the other.

Both at zero is a perfectly good effect, not a mistake: it is one that something else fires with emitParticles.

Where a particle is born, in the emitter's own space.

Deliberately apart from which way it then moves, which is direction and spread below. A ring of sparks flying outwards and a ring of rain falling straight down are the same birth area with different velocities, and folding the two together makes the second one impossible to say.

Where a particle is born in three dimensions, in the emitter's own space.

The same split as the flat shapes, position only, with one exception: a cone also aims what it emits, along its own wall, because a cone whose particles ignored it would be a disc.

How a particle is laid over what is already there.

alpha covers, which is what smoke and dust want. additive adds light, which is the only way fire, sparks and anything glowing read as bright: two overlapping embers should be brighter than one, and under alpha they are merely nearer.

Something solid in a flat scene, as far as particles are concerned.

It belongs to the scene and not to any effect: every effect that says how it collides runs into it. It is placed by the object it is on, so a moving platform takes its collider with it.

Something solid in a scene in three dimensions, as far as particles are concerned. The same thing as the flat one, one dimension up.

The shapes a flat collider can take, measured on its object: the object's placement moves, turns and stretches it.

plane is an endless floor along the object's own y = 0, solid below it on screen, which with y growing downwards is the side where y is larger.

The shapes a collider in three dimensions can take, measured on its object.

plane is an endless floor through the object's own origin, solid below it, with +y up. Turn the object and it becomes a slope or a wall.

What a particle does when it runs into something solid in the scene.

Only how it reacts, never what it runs into: the file is shared by every room that uses the effect, so where the floor is belongs to the scene, which says it with colliders on its objects. Sparks bounce and rain is gone, in any room.

One stop of the colour a particle walks through as it ages. t is 0 at birth and 1 at death.

What a scene may turn up or down about an effect without writing a second file.

The file says what the effect is, and it is shared: three torches are one document. These are the handful of things one of those torches may disagree with it about.

It exists because every game eventually wants "the same explosion, half the size", and making that a second file is what forks an effect into six near-copies nobody can keep in step.

A pair of numbers a particle draws one value from when it is born.

Written as [min, max], or as a bare number when every particle should get the same one.

An emitter in three dimensions: particles in world units, drawn as squares that always face the camera.

Everything but its placement is the flat emitter's, field for field, and means the same thing: the same file on the same terms, the same tint, the same verbs. What it does not share is where it is, which here is a place in space with a turn of three angles, and the answer to where it ended up is a matrix rather than a flat placement, exactly as it is for a model.

What createParticles3d is asked for: the flat emitter's options, placed in three dimensions.

One stop of how big it is as it ages, as a multiple of the size it was born with.