2d-polygon-self-intersections 中文文档教程
2d-polygon-self-intersections
find self-intersections in a 2d polygon
这个库可能不快,但是很健壮。 强大的事实是它将找到多边形中的所有自相交 - 当然减去共享端点。
您可以预期 O(n^2) 的时间复杂度
为什么我们不使用 Bentley–Ottmann? 我们可能会在未来,但这需要一些时间,并且拥有一个检测自相交的功能机制比一个不存在的机制要好得多。 api 不必为此发生更改。
install
npm install 2d-polygon-self-intersections
use
var isects = require('2d-polygon-self-intersections');
var poly = [
[0, 0],
[10, 0],
[0, 10],
[10, 10]
];
var r = isects(poly);
console.log(r);
// outputs: [ [ 5, 5 ] ]
api
isects(polygon
[, filterFn
])
polygon
- an array of 2 component arrays (i.e. a triangle[[0, 0], [10, 0], [10, 10]]
) or an array of objects:[{x:0, y:0}, {x:10, y:0}, {x:10, y:10}]
filterFn
- a filter function called whenever an intersection is found:filterFn
(isect
,start0
,end0
,start1
,end1
,unique
)isect
- current intersection (e.g.[5, 5]
) - mutations in this array get collectedindex0
- index of the segment (e.g1
)start0
- start of the first segment (e.g[0, 5]
)end0
- start of the first segment (e.g[10, 5]
)index0
- index of the segment (e.g3
)start1
- start of the first segment (e.g[5, 0]
)end1
- start of the first segment (e.g[5, 10]
)unique
- boolean representing whether or not this intersection point has been seen before- return
true
to collect andfalse
to discard
返回< /strong> 如果没有交叉点,则为空数组或表示交叉点的 2 个组件数组的数组。
注意:该库假定多边形是封闭的,因此手动将起点添加为终点无效。
另请注意,每个十字路口有 2 个交叉路口,默认情况下,该库只会报告一个 - 所有交叉路口都是唯一的。 可以使用 filterFn
更改此行为。
license
2d-polygon-self-intersections
find self-intersections in a 2d polygon
This library may not be fast, but it is robust. Robust in the fact that it will find all of the self-intersections in a polygon - minus of course shared endpoints.
You can expect a time complexity of O(n^2)
Why wouldn't we use Bentley–Ottmann? We may in the future, but that is going to take some time and having a functional mechanism for detecting self-intersections is far superior to a non-existant one. The api won't have to change for this to happen.
install
npm install 2d-polygon-self-intersections
use
var isects = require('2d-polygon-self-intersections');
var poly = [
[0, 0],
[10, 0],
[0, 10],
[10, 10]
];
var r = isects(poly);
console.log(r);
// outputs: [ [ 5, 5 ] ]
api
isects(polygon
[, filterFn
])
polygon
- an array of 2 component arrays (i.e. a triangle[[0, 0], [10, 0], [10, 10]]
) or an array of objects:[{x:0, y:0}, {x:10, y:0}, {x:10, y:10}]
filterFn
- a filter function called whenever an intersection is found:filterFn
(isect
,start0
,end0
,start1
,end1
,unique
)isect
- current intersection (e.g.[5, 5]
) - mutations in this array get collectedindex0
- index of the segment (e.g1
)start0
- start of the first segment (e.g[0, 5]
)end0
- start of the first segment (e.g[10, 5]
)index0
- index of the segment (e.g3
)start1
- start of the first segment (e.g[5, 0]
)end1
- start of the first segment (e.g[5, 10]
)unique
- boolean representing whether or not this intersection point has been seen before- return
true
to collect andfalse
to discard
returns an empty array if no interesections or an array of 2 component arrays representing the intersection points.
NOTE: this library assumes the polygon is closed, so manually adding the start point as the end point has no effect.
Also note that there are 2 intersections per crossing, this library by default will only report one - all intersections will be unique. This behavior can be changed with the filterFn
.