Exact fits

[PaulDL-RS]

Dear Jeroen,

How to best handle items wich can exactly fit inside the strip width, like the attached instance ?

Yours,

Paul Durand-Lupinski

square_triangles.json

[JeroenGar]

Hi,

Exact fits are not possible with sparrow for two reasons:

• In order to guarantee feasibility above all else, the Collision Detection Engine inside jagua-rs is designed to 'err on the side of caution' when two shapes are so close to each other that they could cause funkiness with the floating point arithmetic.
  In practice, this means that, when a collision query is too close too call, a false positive is much better than a false negative.
• sparrow relies on a strategy based on sampling to find good placements for items.
  This procedure can produce extremely precise placements but it cannot land on a single exact point.

If you are familiar with the concept of No-Fit Polygons (NFP), you can easily conceptualize this as any placements where the corresponding NFP has no area (points and lines) being impossible.
An extremely small 'NFP area' is fine, but 0 area is not.
(to be clear jagua-rs does not use NFPs at all)

If you increase the height of this strip in your example by just 0.01% (to 2.0001) you will see that it produces the results you desire.
This should only ever really be a problem for toy-instances.

I hope my explanation was somewhat clear.

Best,
Jeroen