Fix transparent blocks

common/everything_registry.ts

@@ -93,10 +93,18 @@ interface BlockStateVariant {
 	y: number;
 }
 
+// solid: fully opaque. cutout: texels are either opaque or see-through (leaves).
+// translucent: blended and sorted back to front (water, glass)
+export const RENDER_LAYERS = ["solid", "cutout", "translucent"] as const;
+export type RenderLayer = typeof RENDER_LAYERS[number];
+
 export interface BlockRegistry {
 	id: string;
 	textures: string | TextureSideTopBottom | TextureFront;
-	transparent?: boolean;
+	// solid when not set. anything else doesn't hide its neighbors' faces
+	render_layer?: RenderLayer;
+	// hide faces between two of this block, like glass and water. defaults to true for translucent blocks
+	cull_same?: boolean;
 	alpha?: number;
 
 	has_collision: boolean;

common/mod_data.ts

@@ -1,6 +1,12 @@
 // the json formats from MODS.md, and converting them to and from the engine's registry entries.
 // the mod loader uses the from_json direction, tests use both to check nothing is lost
-import type { BlockRegistry, BlockStateDefinition, ItemRegistry } from "./everything_registry.ts";
+import {
+	type BlockRegistry,
+	type BlockStateDefinition,
+	type ItemRegistry,
+	RENDER_LAYERS,
+	type RenderLayer,
+} from "./everything_registry.ts";
 
 export const FORMAT_VERSION = 1;
 export const ID_PATTERN = /^[a-z0-9_]+:[a-z0-9_]+$/;
@@ -25,6 +31,9 @@ export interface ManifestJson {
 export interface BlockJson {
 	id: string;
 	textures: BlockTextures;
+	render_layer?: RenderLayer;
+	cull_same?: boolean;
+	// replaced by render_layer, true means translucent
 	transparent?: boolean;
 	alpha?: number;
 	collision?: boolean;
@@ -78,7 +87,8 @@ export interface GridRecipe {
 
 export function block_to_json(block: BlockRegistry, has_item: boolean): BlockJson {
 	const json: BlockJson = { id: block.id, textures: block.textures };
-	if (block.transparent) json.transparent = true;
+	if (block.render_layer && block.render_layer !== "solid") json.render_layer = block.render_layer;
+	if (block.cull_same !== undefined) json.cull_same = block.cull_same;
 	if (block.alpha !== undefined) json.alpha = block.alpha;
 	if (!block.has_collision) json.collision = false;
 	if (block.toughness !== undefined) {
@@ -101,7 +111,9 @@ export function block_from_json(json: BlockJson): { block: BlockRegistry; has_it
 		textures: json.textures,
 		has_collision: json.collision ?? true,
 	};
-	if (json.transparent) block.transparent = true;
+	const render_layer = json.render_layer ?? (json.transparent ? "translucent" : undefined);
+	if (render_layer && render_layer !== "solid") block.render_layer = render_layer;
+	if (json.cull_same !== undefined) block.cull_same = json.cull_same;
 	if (json.alpha !== undefined) block.alpha = json.alpha;
 	if (json.mining) {
 		block.toughness = json.mining.toughness;
@@ -243,7 +255,10 @@ export function validate_block(json: unknown): Problems {
 			(["top", "bottom", "side"].every((k) => typeof textures[k] === "string") ||
 				["front", "side"].every((k) => typeof textures[k] === "string")));
 	if (!texture_ok) problems.push("textures must be a texture id, { top, bottom, side } or { front, side }");
-	for (const key of ["transparent", "collision", "item", "interactive", "replaceable"]) {
+	if (json.render_layer !== undefined && !RENDER_LAYERS.includes(json.render_layer as RenderLayer)) {
+		problems.push(`render_layer must be one of ${RENDER_LAYERS.join(", ")}`);
+	}
+	for (const key of ["cull_same", "transparent", "collision", "item", "interactive", "replaceable"]) {
 		if (json[key] !== undefined && typeof json[key] !== "boolean") problems.push(`${key} must be true or false`);
 	}
 	if (json.alpha !== undefined && (typeof json.alpha !== "number" || json.alpha < 0 || json.alpha > 1)) {