1OGR DXF driver: Known issues
2============================
3
4This is a brief list of known issues (mainly missing features) in the DXF
5driver. Anyone is welcome to contribute code that addresses these issues.
6
7## Reader
8
9* The following DXF entities are not supported at all: MESH, MPOLYGON, RAY,
10TABLE, TOLERANCE, WIPEOUT, XLINE.
11
12### 3DFACE
13
14* There seems to be some ambivalence as to whether 3DFACE entities should be
15represented as outlined polygons, as we currently do, or filled polygons. Any
16input on this issue would be appreciated.
17
18### DIMENSION
19
20* 3D (z-coordinate) and OCS (extrusion) support is absent from both the
21anonymous block logic and the fallback renderer.
22
23* The DIMENSION fallback renderer, used when the anonymous block is absent, is
24pretty rudimentary. I personally don't plan to work on it any further. Note
25that AutoCAD refuses to open DXF files that have a DIMENSION with no anonymous
26block.
27
28### HATCH
29
30* Fill types are not read. Any implementation of fill types (i.e. patterns)
31would need to be somewhat heuristic, given the basic set of choices available
32in the OGR style string spec.
33
34### LEADER
35
36* 3D (z-coordinate) and OCS (extrusion) support is absent.
37
38### LWPOLYLINE
39
40* Width support has not been added.
41
42### MLINE
43
44* Support for MLINESTYLE is missing. This means that only the basic geometries
45of MLINE entities are translated, not the more complex styling properties,
46such as different colors or linetypes for the different elements of the line.
47
48### MULTILEADER
49
50* 3D (z-coordinate) and OCS (extrusion) support is missing. This entity is
51very complex and adding 3D/OCS support would take a long time.
52
53### Text entities
54
55* Text using AutoCAD-specific SHX (plotter) fonts, such as "txt", is
56reported as being in Arial.
57
58* Text with a nonzero oblique angle, or that is upside down and/or backwards,
59will appear normal, due to the lack of support for these properties in an OGR
60style string. I don't think there is too much point adding these to the style
61string spec, as these attributes are little-used and not commonly available in
62other software.
63
64## Writer
65
66* The writer doesn't know about transparency. This means that hidden objects,
67which are represented using fully transparent colors by the reader, do not
68round-trip correctly.
69
70* As noted above, 3DFACE entities are represented by POLYGON geometries with a
71PEN() style tool, a combination which the writer handles poorly.
72
73* The writer does not write out ATTRIB entities for a POINT feature with a
74non-empty BlockAttributes field, that is to say, block attributes are not
75round-tripped. This is certainly a gap in the feature set, but I only plan to
76write this code if someone expresses a need for it.
77
78---
79
80Alan Thomas, ThinkSpatial
81athomas@thinkspatial.com.au
82June 2018
83