feat(config): Update the config to support sky in the style json. BM-…

…1052 (#3314)

### Motivation

Update the config style parser and loader to include sky in the
stylejson.

### Modifications

Add sky type into stylejson

### Verification


![image](https://github.com/linz/basemaps/assets/12163920/1d75956e-ffcf-40a0-8000-cb5064762d69)

![image](https://github.com/linz/basemaps/assets/12163920/852a5d68-de74-429a-8ff3-8ef1d90fb1b4)

packages/config-loader/src/json/parse.style.ts

@@ -11,6 +11,7 @@ export const zStyleJson = z.object({
 
   // TODO it would be good to actually validate all the styles
   layers: z.array(z.unknown()),
+  sky: z.unknown(),
 });
 
 export type StyleJsonConfigSchema = z.infer<typeof zStyleJson>;

packages/config/src/config/vector.style.ts

@@ -40,6 +40,24 @@ export interface Layer {
   'source-layer'?: string;
 }
 
+/** Sky MapLibre Style Spec, all valuables support interpolate expressions, as unknown format */
+export interface Sky {
+  /** The base color for the sky. Optional Defaults to #88C6FC */
+  'sky-color'?: string | unknown[];
+  /** The base color at the horizon. Optional Defaults to #ffffff */
+  'horizon-color'?: string | unknown[];
+  /** The base color for the fog. Requires 3D terrain. Optional Defaults to #ffffff */
+  'fog-color'?: string | unknown[];
+  /** How to blend the fog over the 3D terrain. Optional number in range [0, 1]. Defaults to 0.5 */
+  'fog-ground-blend'?: number | unknown[];
+  /** How to blend the fog color and the horizon color. Optional number in range [0, 1]. Defaults to 0.8. */
+  'horizon-fog-blend'?: number | unknown[];
+  /** How to blend the the sky color and the horizon color. Optional number in range [0, 1]. Defaults to 0.8. */
+  'sky-horizon-blend'?: number | unknown[];
+  /** How to blend the atmosphere. Optional number in range [0, 1]. Defaults to 0.8. */
+  'atmosphere-blend'?: number | unknown[];
+}
+
 export interface Terrain {
   source: string;
   exaggeration: number;
@@ -73,6 +91,9 @@ export interface StyleJson {
   /** Layers will be drawn in the order of this array. */
   layers: Layer[];
 
+  /** The map's sky configuration */
+  sky?: Sky;
+
   /** OPTIONAL - A global modifier that elevates layers and markers based on a DEM data source */
   terrain?: Terrain;
 }

packages/lambda-tiler/src/routes/tile.style.json.ts

@@ -70,6 +70,7 @@ export function convertStyleJson(
   if (style.metadata) styleJson.metadata = style.metadata;
   if (style.glyphs) styleJson.glyphs = convertRelativeUrl(style.glyphs, undefined, undefined, config);
   if (style.sprite) styleJson.sprite = convertRelativeUrl(style.sprite, undefined, undefined, config);
+  if (style.sky) styleJson.sky = style.sky;
 
   return styleJson;
 }