Welkin - Skies And Weather That Draw Themselves

Every image on this page was rendered by the product itself. There is not one sprite in the package.

Most day/night assets tint the scene you already have. Welkin draws the sky — the gradient that belongs to the hour, the cloud deck standing in it, the horizon behind it, the sun and moon, the weather falling through it, and the light state the rest of your scene can read so everything in the frame agrees with the sky.

sky = wlk_sky_create(52, 7);                        // latitude, seed
wlk_sky_step(sky, delta_time / 1000000);
wlk_sky_draw(sky, 0, 0, room_width, room_height);   // the whole backdrop, one call

43 authored forms, and the volume is the point

• 14 real cloud genera — cumulus humilis through cumulonimbus, stratus, nimbostratus, altocumulus, cirrus, cirrostratus, cirrocumulus, lenticular, mammatus. They differ in silhouette, which is what you can actually tell apart in a sky.
• 10 horizon profiles, each in three depth ranks — open sea, plains, rolling downs, conifer ridge, broadleaf woodland, foothills, mountains, alpine peaks, mesa country, city skyline.
• 11 drawn weathers — drizzle, rain, downpour, snow, blizzard, sleet, hail, mist, fog, lightning, and a rainbow that only appears when the sun is low enough for the arc to stand above the horizon.
• 8 moon phases, with a terminator that is a half ellipse — so a crescent is a crescent, not a quarter with a bite taken out of it.

The colour is the product

The sky is a five-stop Oklch ramp whose lightness, chroma and hue travel independently, keyed at seven real astronomical altitudes. Clouds take their material from that ramp: their lit face is sunlight, their shadow face is the sky beside them. Nothing is authored per hour — a sunset cloud is orange on top and violet underneath because the sky above it is orange and the sky beside it is violet.

The seasons are not presets. They fall out of the solar position equation. Latitude 68 in June genuinely has a different day from latitude 8, and midwinter at 52 is genuinely dark at five in the afternoon.

Your scene can read the sky

var _L = wlk_sky_light(sky);
//  _L.alt  _L.az  _L.direct  _L.ambient  _L.warmth  _L.flash  _L.lx,_L.ly

Tint sprites, colour your own shadows, decide whether the streetlamps are on, or shade your art from the real direction of the real sun.

COMPATIBILITY

• GameMaker 2024.11 and newer. Built and verified against runtime 2024.14.4.268.
• Pure GML. No extensions, no DLLs, no shaders, no sprites, no texture pages.
• Nothing global is unprefixed — every script, macro and global is wlk_ / WLK_.
• It draws into the rectangle you give it and does not touch your rooms, layers or cameras.
• Import: Tools ▸ Import Local Package ▸ Welkin.yymps, import all, open rm_welkin_demo, press Run.

What it is NOT

This is a backdrop system, not a 2D lighting engine. It does not light your sprites, cast shadows from them or touch normal maps. It hands you a light state and what you do with it is yours. If you need per-sprite lighting, buy a lighting extension — they are good, and this is not one.

Verification

The package ships an in-engine self-test: 284 assertions, 0 failures, run inside a real Igor-built executable — geometry and total turning on every authored outline, the Oklch ramp and the sRGB chroma ceiling, the solar position equation, the silhouette-distinctness matrices, the weather conditioning, the rainbow and the moon phases.

That proves the maths and the shapes. It cannot prove a picture is attractive — that part was reviewed by opening every image and looking.

What you get

Raw readable GML, header-documented, 12 scripts. A runnable demo room. A Readme with the whole integration in three calls. No minified code, no obfuscation.

Made by Core Systems Asset Factory. Built with AI assistance — disclosed in the tags below.