Mirrored coordinates of some entries. about dxf HOT 3 CLOSED

What viewers are you using and how was the DXF file created? The DXF snippet you posted appears correct, but with one caveat; look down to lines 155-160:

210
0.0
220
0.0
230
-1.0

Those codes represent the circle's normal vector which means the circle isn't "facing" the screen, it's "facing" away. The normal vector (called "extrusion" by the DXF spec) is usually (0,0,1), but here it's (0,0,-1).

from dxf.

Thank you for your reply. How this file was generated I do not know, it is a custom file, researching its origin is difficult.
But yes, I understood your answer, and came to the same conclusion when I was trying to solve this yesterday.
So this vector really tells about the inversion of the plane. But this does not indicate the direction of reversal. It can be due to X, due to Y or other conditions. I solved it for myself by Mirroring the X coordinate, but this is not a valid solution, it just seemed better to me. I meant changing the sign of the X coordinates, that is, turning around the Y axis.
So I agree that the library reads this data correctly, and it even reads that vector.
But how to correctly process it remains to be discovered, although it is possible outside the library.
In any case, such a vector is not unambiguous, which creates problems due to the absence of rules.
Perhaps you have information on the sequence of use of this vector?
Thank you.

from dxf.

Your behavior of mirroring the X coordinate is correct. DXF files use Autodesks's Arbitrary Axis Algorithm which states how to compute the axes, and in this instance, the first clause is relevant (written differently for clarity:

if (abs(normal.X) < 1/64 && abs(normal.Y) < 1/64))
{
    xAxis = (0, 1, 0) X normal; // the result of this is that the object's x axis is now (-1, 0, 0), which is the mirroring you did
}

from dxf.