Closed 2D_Polyline

[danikolovv]

Hello,

This is the way I found to be used in polyline to take a closed form: if (entity_polyline_2d->flag)
Currently, some polylines, without actually being with closed ends, are taken with closed ends.
Is there something else that must be used for ensuring the polyline to be extracted correctly?

Thanks,
Daniel

[maslke]

try this:

if (entity_polyline_2d->flag & 512 && entity_polyline_2d -> num_points > 3) {
// do sth
}

[maslke]

It also explains the flag in the source code

BITCODE_BS flag;             
 /*!< DXF 70
                                  512 closed, 128 plinegen, 4 constwidth, 8 elevation, 2 thickness
                                  1 extrusion, 16 num_bulges, 1024 vertexidcount, 32 has_widths */

[danikolovv]

Hello,

I think @rurban said the right value that should stay after the greater sign.

Since you shared, I would like more information on these comments.

BITCODE_BS flag;             
 /*!< DXF 70
                                  512 closed, 128 plinegen, 4 constwidth, 8 elevation, 2 thickness
                                  1 extrusion, 16 num_bulges, 1024 vertexidcount, 32 has_widths */

Thanks,
Daniel

[rurban]

You need to lookup AutoCAD or DXF docs for specific bit values

[danikolovv]

Hello,

I understand.

What does the bitwise AND operation with 512 do in the following code?

if (entity_polyline_2d->flag & 512) { }

[maslke]

if lwpolyline was closed, the 10th bit value of flag would be 1 , otherwise it was 0.

1. flag & 512 == 512, the polyline was closed.
2. flag & 512 == 0, the polyline was not closed.