dxf does not support OCS

[pooyapm]

Many objects in DXF file use OCS (Object Coordinate Systems) instead of WCS (World coordinate Systems). For example, "LWPOLYLINE" uses OCS for it's vertices. OCS should be converted to WCS when an OGRGeometry is creating. OCS definition is documented in DXF reference. The attached file contains the necessary code for converting OCS to WCS conversion and edited OGRDXFLayer::TranslateLWPOLYLINE() function using this conversion.

[warmerdam]

Could you provide a file demonstrating LWPOLYLINEs using OCS?

[pooyapm]

Replying to warmerdam: The attached file "LWPOLYLINE-OCS.dxf" contains 6 3DPOLYLINEs (in WCS) and 6 LWPOLYLINEs (in OCS). If you open DXF file using a text editor, you can see negative coordinates for some LWPOLYLINEs, but if open it using AutoCad?, all coordinates are positive (The file is part of a real map with UTM projection).

[warmerdam]

I have substantially reworked the patch and it is applied in trunk (r18752) and 1.7 (r18754).

I would appreciate it if you could test the result to see if it is correct.

It should now be possible to add OCS handling to other element types as appropriate just by calling ApplyOCSTransformer() on the geometry; however, I prefer not to do this without test files.

[rouault]

Attached a patch that fixes use of wrong index in CrossProduct?() (and also remove unused member variables) that likely explains the failure on epimetheus slavebot. ogr_dxf_9 should be updated accordingly.

[rouault]

Fix r18752

[rouault]

I meant failure on *telascience* slavebot

[warmerdam]

Patched in trunk (r18756) and 1.7 branch (r18755).

Thanks