//

// GeometryCache.swift

// ShapeScript Lib

//

// Created by Nick Lockwood on 06/08/2021.

// Copyright © 2021 Nick Lockwood. All rights reserved.

//

import Euclid

#if canImport(LRUCache)

import LRUCache

#endif

public final class GeometryCache {

private let cache: LRUCache<Key, Mesh>

public init(memoryLimit: Int = 1_000_000_000) {

cache = LRUCache(totalCostLimit: memoryLimit)

}

}

extension GeometryCache {

struct Key: Hashable {

let type: GeometryType

let material: Material?

let smoothing: Angle?

let transform: Transform

let children: [Key]

}

subscript(geometry: Geometry) -> Mesh? {

get { cache.value(forKey: geometry.cacheKey) }

set {

cache.setValue(

newValue,

forKey: geometry.cacheKey,

cost: newValue?.memoryUsage ?? 0

)

}

}

}

private extension Mesh {

var memoryUsage: Int {

let vertexSize = MemoryLayout<Vertex>.stride

let polygonSize = 512 // Estimated

return polygons.reduce(0) { count, polygon in

count + polygonSize + polygon.vertices.count * vertexSize

}

}

}