The Atmospheric journey
Rain, snow, stars, fireflies, insects, bubbles, dust, embers, fog, leaves, lightning, shooting stars. One system, sixteen looks: items born in zones of the screen, living for a while and replaced, or kept alive for as long as the effect runs. One of the four things this tool designs, beside flows, coin flights and win lines.
One system at a time
ChixyFX describes one particle system and the game renders it. The start screen asks which one you are designing, from left to right:
- Atmospheric - this page.
- Flow - a stream of items through a shaped field you draw: smoke, a waterfall, a portal. See the Flow journey.
- Coins - a flight from a symbol to a pot.
- Win lines - the effect along a payline.
The header shows which one you are in. Start over takes you back to the start screen; nothing is lost until you pick there, and Back to the design returns you. A saved session remembers its system, so Open a saved session lands you in the right one. Each system saves and exports its own file, named -flight, -winline, -flow or -atmospheric, and the game stacks them: rain in one file, fireflies in another.
[atmospheric_02 - The start screen over the tool: the four big choice buttons Atmospheric, Flow, Coins, Win lines with their one-line descriptions, and Open a saved session below. About 1100 px wide.]
What an item is
Every item is a very short flight with no path. It is born somewhere inside a zone, moves under the forces for its lifetime, and is replaced - or, with Infinite life on in the Population group, simply keeps going and is never replaced, which is what anything that loiters wants: butterflies in a bush, fish in a tank, a swarm of flies. Because it is a flight, everything you know from the other journeys rides on it unchanged:
- The Coin tab, called Item here, is the item's picture: a still or a sequence, its Transform, blend, a flat Opacity (the heaviness knob of a rain or snow field), size and opacity over its life, tint, and its Rotation. Align to path turns it to its travel direction (a rain streak, a leaf); Keep upright mirrors a side-view bird when it flies left.
- The Trails tab gives it a tail: a shooting star is a bright dot with a ribbon behind it.
- The Sparks tab sheds particles from it: fairy dust behind a bird.
- The Hit tab fires when it dies, is born, or both: a bubble pops at the surface, a drop splashes at the bottom edge.
Trails, sparks and hits cost sprites per item, so while any of them is on, Count is capped at 24. Rain and snow are item-only and go to 600.
Where items are born, how many, how they move and when is all on the Paths tab: Zones.
The presets
Every preset is the same system with different numbers. The columns are the only things that differ. Load one, then change what you like.
| Preset | Zone and edge | Population | Motion | Look |
|---|---|---|---|---|
| Rain | whole stage grown above, wrap | 350 x 4 s, depth 60 % | gravity 1400, drag 3, a little wind, align to path | streak, normal, half opacity |
| Snow | same, wrap | 250 x 8 s, depth 70 % | gravity 120, drag 2, turbulence 40, wander 30 at 0.3 Hz, slow spin | snowflake |
| Stars | a band across the sky, feather 120 | 180 x 3 s, randomness 80 %, same spot, depth 80 % | none | glint, add, opacity 0 to 1 to 0 |
| Fireflies | an ellipse, feather 80, soft bounce 120 px | 25 x 6 s | wander 90 at 0.4 Hz, gravity -10 | soft disc, add, yellow-green, pulsing |
| Insects | a polygon, feather 40, bounce | 20 x 5 s | wander 140 at 1.2 Hz, align to path | bug |
| Bubbles | a tank, born on the bottom edge, kill | 60 x 5 s | gravity -300, drag 3, wander 25 | bubble, screen, growing |
| Dust motes | whole stage, wrap | 120 x 10 s, depth 80 % | wander 40 at 0.15 Hz, wind 15 | tiny disc, add, faint |
| Embers | a strip, born on the bottom edge, kill | 80 x 3 s | gravity -250, drag 2, turbulence 30, wander 50 | sparkle, add, orange to red to dark |
| Fog wisps | a lane starting 1000 px off the left, born on its left edge, free | 16 x 30 s, depth 30 % | wind 150, wander 40 at 0.04 Hz | wisp, huge, screen, alpha 0.14, 3.6 s fades |
| Petals / leaves | whole stage grown above, wrap | 60 x 7 s, depth 40 % | gravity 90, drag 2, wind 60, wander 80, spin, wobble, align to path | leaf, pink tint |
| Lightning | the sky | 1 x 0.5 s, cycle on 0.2 s off 7 s, randomness 100 % | none | huge disc, screen, a double flash |
| Coin rain | whole stage grown above, wrap | 60 x 5 s, depth 50 % | gravity 900, drag 1, spin | the coin flip |
| Water glints | a flat ellipse, feather 60 | 90 x 1.5 s, randomness 90 %, same spot | none | glint, add, a sharp spike |
| Shooting stars | the upper sky | 3 x 1.2 s, cycle on 1 s off 6 s | burst 1400 px/s at 150 degrees | bright disc plus a ribbon trail |
Birds, butterflies, clouds and god rays are the same recipes with an uploaded picture: a side-view bird sequence with Keep upright on the Insects preset, a cloud picture on Fog wisps, a beam picture on Stars with a slow opacity loop.
A tank, a bush, a meadow. For anything that should stay on screen rather than pass by, start from Fireflies and change four things in the Population and Motion groups: Infinite life on (nothing is ever replaced), At the edge on Soft bounce with a Turn distance of about 120 px (they turn back well before the outline, so the zone never reads as a wall), Size variance around 2 (twenty butterflies of the same size look cloned), and two or three Variants on the Item tab (three different fish, a third each). Press Flatten item curves if the Population group warns that the item's curves blink.
Bubbles behind a fish, dust behind a leaf. A sparkle layer on an item that lives a long time needs Follow path at 0 % in its Emission group (Sparks tab). At the normal 100 % each spark rides along the item's route after it is born, and on a 30 second Lifetime that ride takes it past the item. At 0 % a bubble stays where the fish breathed it out and only its Gravity moves it. If the bubbles still cover the fish, switch off Draw above the coin on that layer.
[atmospheric_01 - A contact sheet, two rows of three, each cell a stage crop of a preset over the same game screenshot: Rain, Snow, Stars, Fireflies, Bubbles, Embers. Label each cell with the preset name. About 1350 px wide.]
Placeholder pictures
The presets use pictures the tool draws for itself when it starts: a streak, a snowflake, a bug, a bubble, a star glint, a wisp and a leaf, all white so tints apply. They are placeholders. Replace any of them with Upload image(s) on the Item tab; a numbered sequence becomes an animated item (a flapping bird, a spinning leaf). A set of different pictures with Frames set to Random image gives every item its own picture, so a snowfall or a swarm is not thirty copies of one flake. For a few distinct looks that are themselves animated, upload them one by one into the Item tab's Variants group instead, and give the field a Size variance in the Population group so the items are not all one size. Directional pictures should point right, so Align to path needs no offset.
The reel house in front
Weather belongs behind the reels. On the Board tab, press Add element and pick a PNG with transparency of what sits in front of the effect in the game: the reel house, the UI frame, a character. Drag its card down so it sits just above the Board card, between the board and element 0, then draw your zones with it on screen and you can see exactly where items will be visible. The Zones tab's Depth puts the whole system behind those pictures or in front. A stage element is a design aid: never exported, and only drawn into a render when you tick Include the stage elements.
What the game gets
Export Effect writes chixy-fx-effect-atmospheric.zip: the zones, the population, the motion, the cycle and the depth, plus the item and its layers exactly as in the other journeys, and every picture the items that are switched on draw, the generated placeholders included. Every rule the tool uses is written into the file as notes, including how the random draws work, so the game shows the same field from the same seed. Nothing is baked per item, so the settings stay small however many items there are.
Everything is exact at any moment. There is no simulation running underneath: each item's position is worked out from the clock and its seed. Pause, drag the Scrub slider, render frame 5000 - it is always the same field.