LibreCAD HATCH misrenders in AutoDesk software about librecad HOT 4 OPEN

it's rendered correctly in the lastest development version.

from librecad.

@dxli Yes, but not in the Autodesk software. My point is that the HATCH boundary geometry may be invalid, at least according to Autodesk, which, I believe, owns the DXF format.

from librecad.

dxf format specifies:

1. number of loops;
2. edges of a loop;
3. edge type (lines here);
4. edge line positions.

Beyond that, we don't simulate Autodesk behaviors. In this particularly case, valid loops can be created from edges, so hatch is created this way.

from librecad.

The DXF reference for HATCH SOLID is not very specific about the composition of boundary path data. There is much room for interpretation.
Basically the same applies as in OSGeo/gdal#9240, namely that the created geometry is invalid.

So what LibreCAD can do is to prohibit the use of non intersecting/including multi loop boundaries for hatch. But somebody might see this as feature and will be disappointed when we change it.

As we know the code how the hatch is created, we also have the working code to render this as expected. But we don't know the closed code from Autodesk, so it would require some valuable efforts to reverse-engineer the Autodesk code to find a way to create this special case of HATCH in a DXF.

The conclusion is, that you simply create two hatch, one for each square, and you will have a DXF which is valid for OSGeo, Autodesk and LibreCAD.

from librecad.