import type { DrawGroup } from "./Material"
import type { Vec3 } from "../math/Vec3"

export type Bounds3 = {
  minX: number
  minY: number
  minZ: number
  maxX: number
  maxY: number
  maxZ: number
}

/** One cullable section of static world geometry with two engine-supported LODs. */
export type Chunk = Bounds3 & {
  readonly near: readonly DrawGroup[]
  readonly far: readonly DrawGroup[]
}

export namespace Chunk {
  export function isFar(chunk: Chunk, eye: Vec3, lodDistance: number): boolean {
    if (!(lodDistance < Infinity)) {
      return false
    }
    const dx = eye.x - Math.max(chunk.minX, Math.min(chunk.maxX, eye.x))
    const dy = eye.y - Math.max(chunk.minY, Math.min(chunk.maxY, eye.y))
    const dz = eye.z - Math.max(chunk.minZ, Math.min(chunk.maxZ, eye.z))
    return dx * dx + dy * dy + dz * dz > lodDistance * lodDistance
  }
}