[Feature request] Check if a point is inside a shape

[marcospassos]

It would be nice to have a method that checks if a 2DPoint is inside or outside the boundaries of a given shape.

[thelonious]

This is implemented in some of the intersection routines. However, my current thinking is to pull this functionality out into a separate IntersectionQuery class. The current intersection code could be streamlined a bit (and made a little faster as a result) if I remove this kind of logic. Likewise, these types of queries often involve simpler math than calculating intersections.

Out of curiosity, do you need this for any shapes in particular?

[marcospassos]

For now, we're using a suboptimal solution that involves creating a line with as a point Shapes.line(x-0.5, y-0.5, x, y) (once 0.5 is less than one pixel, no collateral effects here). However, a more robust solution would be very appreciated :).

Out of curiosity, are you looking for this to supported for any shapes in particular?

As the shape is configurable, we're not looking for a form in particular.

However, my current thinking is to pull this functionality out into a separate IntersectionQuery class.

Please, let me know if decide to pull out such feature.

[thelonious]

Are you looking for something like this? Please note that these have not been tested in any way, but it should give you an idea of what I'm thinking.

[marcospassos]

Yeah, but I would like to suggest an API more close to the Intersection:

const shape = Shapes.circle(10, 10, 50);
const point = new Point2D(10, 20);

IntersectionQuery.containsPoint(shape, point);

What do you think?

[thelonious]

Agreed, something like that would be nicer. My thinking is that I would approach this like Intersection where you could call the low-level API directly (which is what I'm using in my example) and then there would be a convenience method that figures out what method to invoke for you. The low-level methods use kld-affine types and Numbers only. The convenience function would use types like you're showing in your example: i.e., IntersectionArgs.

[marcospassos]

Perfect! It definitely gets the job done. Looking forward to testing it on our app.

Btw, as this new class is completely isolated, it looks like a good point to start with unit tests :)

[marcospassos]

@thelonious, any plans to release the InteserctionQuery?

[thelonious]

I started a new full-time job this month which has limited my time considerably. Is it useful to you in its current form? There's not much there.

[Grepsy]

It would be very useful to me, even in it's current form. I'm mainly looking for the pointInPolygon functionality. Would it be possible to release the current IntersectionQuery stuff?

[thelonious]

Thanks @Grepsy. I went ahead and pushed v0.4.0. I incremented the minor revision since this is an API change, but really all this does is expose IntersectionQuery. I've also added the start of a new section on that class in the README

[Grepsy]

Great, thanks a lot!