(undefined)
+
+ const onSetup = useCallback((canvas: HTMLCanvasElement) => {
+ if (renderer.current) {
+ renderer.current.setStructure(structure)
+ return
+ }
+ if (!resources || !shown) return
+ const gl = canvas.getContext('webgl')
+ if (!gl) return
+ renderer.current = new StructureRenderer(gl, structure, resources, { useInvisibleBlockBuffer: false })
+ }, [resources, shown, structure])
+ const onResize = useCallback((width: number, height: number) => {
+ renderer.current?.setViewport(0, 0, width, height)
+ }, [resources])
+ const onDraw = useCallback((transform: mat4) => {
+ renderer.current?.drawStructure(transform)
+ }, [])
+
+ return <>
+
+ setSeed(randomSeed())} />
+
+
+
+
+
+}
diff --git a/src/app/components/previews/WorldgenUtils.tsx b/src/app/components/previews/WorldgenUtils.tsx
new file mode 100644
index 00000000..03f21c63
--- /dev/null
+++ b/src/app/components/previews/WorldgenUtils.tsx
@@ -0,0 +1,106 @@
+import type { Random } from 'deepslate'
+import { BlockState } from 'deepslate'
+import { clamp, isObject } from '../../Utils.js'
+import type { VersionId } from '../../services/index.js'
+
+export type WorldgenUtilsContext = {
+ random: Random,
+ version: VersionId,
+ nextFloat(): number,
+ nextInt(max: number): number,
+ nextGaussian(): number,
+}
+
+export function nextGaussian(random: Random) {
+ return () => Math.sqrt(-2 * Math.log(1 - random.nextFloat())) * Math.cos(2 * Math.PI * random.nextFloat())
+}
+
+export function normalizeId(id: string) {
+ return id.startsWith('minecraft:') ? id.slice(10) : id
+}
+
+export function sampleInt(value: any, ctx: WorldgenUtilsContext): number {
+ if (typeof value === 'number') {
+ return value
+ } else if (value.base) {
+ return value.base ?? 1 + ctx.nextInt(1 + (value.spread ?? 0))
+ } else {
+ switch (normalizeId(value.type)) {
+ case 'constant': return value.value
+ case 'uniform': return value.value.min_inclusive + ctx.nextInt(value.value.max_inclusive - value.value.min_inclusive + 1)
+ case 'biased_to_bottom': return value.value.min_inclusive + ctx.nextInt(ctx.nextInt(value.value.max_inclusive - value.value.min_inclusive + 1) + 1)
+ case 'clamped': return clamp(sampleInt(value.value.source, ctx), value.value.min_inclusive, value.value.max_inclusive)
+ case 'clamped_normal':
+ const normal = value.value.mean + ctx.nextGaussian() * value.value.deviation
+ return Math.floor(clamp(value.value.min_inclusive, value.value.max_inclusive, normal))
+ case 'weighted_list':
+ const totalWeight = (value.distribution as any[]).reduce((sum, e) => sum + e.weight, 0)
+ let i = ctx.nextInt(totalWeight)
+ for (const e of value.distribution) {
+ i -= e.weight
+ if (i < 0) return sampleInt(e.data, ctx)
+ }
+ return 0
+ }
+ return 1
+ }
+}
+
+export function resolveAnchor(anchor: any, _ctx: WorldgenUtilsContext): number {
+ if (!isObject(anchor)) return 0
+ if (anchor.absolute !== undefined) return anchor.absolute
+ if (anchor.above_bottom !== undefined) return anchor.above_bottom
+ if (anchor.below_top !== undefined) return 256 - anchor.below_top
+ return 0
+}
+
+export function sampleHeight(height: any, ctx: WorldgenUtilsContext): number {
+ if (!isObject(height)) throw new Error('Invalid height provider')
+ if (typeof height.type !== 'string') {
+ return resolveAnchor(height, ctx)
+ }
+ switch (normalizeId(height.type)) {
+ case 'constant': return resolveAnchor(height.value, ctx)
+ case 'uniform': {
+ const min = resolveAnchor(height.min_inclusive, ctx)
+ const max = resolveAnchor(height.max_inclusive, ctx)
+ return min + ctx.nextInt(max - min + 1)
+ }
+ case 'biased_to_bottom': {
+ const min = resolveAnchor(height.min_inclusive, ctx)
+ const max = resolveAnchor(height.max_inclusive, ctx)
+ const n = ctx.nextInt(max - min - (height.inner ?? 1) + 1)
+ return min + ctx.nextInt(n + (height.inner ?? 1))
+ }
+ case 'very_biased_to_bottom': {
+ const min = resolveAnchor(height.min_inclusive, ctx)
+ const max = resolveAnchor(height.max_inclusive, ctx)
+ const inner = height.inner ?? 1
+ const n1 = min + inner + ctx.nextInt(max - min - inner + 1)
+ const n2 = min + ctx.nextInt(n1 - min)
+ return min + ctx.nextInt(n2 - min + inner)
+ }
+ case 'trapezoid': {
+ const min = resolveAnchor(height.min_inclusive, ctx)
+ const max = resolveAnchor(height.max_inclusive, ctx)
+ const plateau = height.plateau ?? 0
+ if (plateau >= max - min) {
+ return min + ctx.nextInt(max - min + 1)
+ }
+ const n1 = (max - min - plateau) / 2
+ const n2 = (max - min) - n1
+ return min + ctx.nextInt(n2 + 1) + ctx.nextInt(n1 + 1)
+ }
+ default: throw new Error(`Invalid height provider ${height.type}`)
+ }
+}
+
+export function sampleBlockState(provider: any, _ctx: WorldgenUtilsContext): BlockState {
+ const type = provider.type.replace(/^minecraft:/, '')
+ switch (type) {
+ case 'simple_state_provider': {
+ return BlockState.fromJson(provider.state)
+ }
+ }
+ return BlockState.AIR
+}
diff --git a/src/app/components/previews/index.ts b/src/app/components/previews/index.ts
index e33b5cd4..b0b98fa3 100644
--- a/src/app/components/previews/index.ts
+++ b/src/app/components/previews/index.ts
@@ -5,6 +5,7 @@ export * from './BiomeSourcePreview.js'
export * from './BlockStatePreview.jsx'
export * from './DecoratorPreview.js'
export * from './DensityFunctionPreview.js'
+export * from './FeaturePreview.jsx'
export * from './LootTablePreview.jsx'
export * from './ModelPreview.jsx'
export * from './NoisePreview.js'