Hi,


On 26-9-2013 23:45, Adam Wulkiewicz wrote:

2. those are potentially ok:
    a) t+uu, m+uu (see: '2 within t,uu.svg', '2 not within t,uu.svg', '2 within m,uu.svg')
    b) t+cc, m+cc (see: '2 [not] within (t|m),cc.svg')
    So I think that for those I also need to check if points of touching segments are inside. But is it sufficient? Probably yes assuming the 'no crossing' policy (point 4) is used.

- uu is normally discarded. But it gives sometimes extra (necessary) information and therefore it is still generated. In 2-not-within it gives this information: there is one intersection point, uu, nothing more -> we know that one is not inside of the other, so we can return false

I must disagree here, see e.g. attached traverse_intersection_52. The containing polygon may touch itself and the contained polygon may be touching the first one in the same point but still be within it.

That is right but I wrote (at least I meant, let met add "only"): if there is only one intersection point, uu, nothing more... If there is anything more than uu, we can discard it, its information is useless.