ishape-rust / ioverlay Goto Github PK

I found a issue when using ShapeType::Subject in FloatOverlay and would like to report it.

I added only ShapeType::Subject paths for FloatOverlay and tried to do graph.extract_shapes with OverlayRule::Subject, but the calculation does not seem to be correct.

overlay.add_paths(&shape, ShapeType::Subject);  
let graph = overlay.build_graph(FillRule::NonZero);
let shapes = graph.extract_shapes(OverlayRule::Subject);

In the library code, src/core/float_overlay.rs calculates union_rect from subj_rect and clip_rect, but there seems to be a problem in this part.
When subj_rect and clip_rect are created with F64Rect::with_shape, if empty paths are inserted, rects with -f64::MAX min and max values are created.
Calculating union_rect based on these all -f64::MAX rects will result in an incorrect rect, and since PointAdapter is calculated based on it, the process will be incorrect.

To fix the above problem, it seems that if self.subj_paths or self.clip_paths is empty, it is necessary to create a PointAdapter by calculating the rect with only the other one.

More to the point, it might be better to return Result Err if build_graph is called with both self.subj_paths and self.clip_paths empty.

I get that you have some interactive docs in https://ishape-rust.github.io/iShape-js/overlay/stars_demo.html but right now you have ZERO comments in your code. When I use a lib it would be nice to at least know just a line or two what a function does or what an enum is. Like wth is ShapeType?? and what is the difference between Subject and Clip??

A simple /** explain here */ or /// before the enum or function would make it much easier to follow when coding as you get that as an editor hint. It does not need to be an essay, but just something.

It isn't fully clear to me how to interpret the output of the algorithm. It's a Vec<Vec<Vec<F64Point>>>, and I understand it represents a set of polygons, that can have holes. I am not familiar with the convention for representing holes though. Is the following assumption correct:

• The outer Vec represents a set of shapes
• Each shape Vec represents a collection of polygons, where the first polygon is the outer boundary, and all subsequent polygons are holes in this boundary
• Each polygon Vec represents a collection of points, where every two consecutive points (cyclically) make up the boundary edge of the polygon

I think it would be worth being very eplicit about this in the docs/comments, for people that are not familiar with the conventions.

But it's worth mentioning that overall this library looks really great!