63 lines
1.4 KiB
TypeScript
63 lines
1.4 KiB
TypeScript
interface Vec2 { x: number; y: number }
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export type CompareVectorFn = (v1: Vec2, v2: Vec2) => number
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const comparePointCache: Map<string, CompareVectorFn> = new Map()
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const ALLKEY = ['x', 'X', 'y', 'Y', 'z', 'Z']
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const KEY = ['x', 'y', 'z']
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/**
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* 构建返回一个用来排序的函数.根据key创建排序规则.
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*
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* 当key = "xyz" 时,点集按 x从小到大,y从小到大 z从小到大
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* key = "X" 时,点集按 x从大到小
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* 以此类推.
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*
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* 例子:
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* let pts:Vector3[] =...;
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* pts.sort(comparePoint("x")); //x从小到大排序
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* pts.sort(comparePoint("zX")); //z从小到大 x从大到小
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*
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* @export
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* @param {string} sortKey
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*/
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export function ComparePoint(sortKey: string): CompareVectorFn
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{
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if (comparePointCache.has(sortKey))
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return comparePointCache.get(sortKey)
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let sortIndex = []
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for (let char of sortKey)
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{
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let index = ALLKEY.indexOf(char)
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let i2 = index / 2
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let ci = Math.floor(i2)
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sortIndex.push([KEY[ci], i2 > ci ? 1 : -1])
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}
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let compareFunction = (v1: Vec2, v2: Vec2): number =>
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{
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if (!v1)
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return -1
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if (!v2)
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return 1
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for (let s of sortIndex)
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{
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let vv1 = v1[s[0]]
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let vv2 = v2[s[0]]
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if (vv1 === vv2)
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continue
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if (vv2 > vv1)
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return s[1]
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else return -s[1]
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}
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return 0
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}
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comparePointCache.set(sortKey, compareFunction)
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return compareFunction
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}
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