1.. _vector.dwg: 2 3AutoCAD DWG 4=========== 5 6.. shortname:: DWG 7 8.. build_dependencies:: Open Design Alliance Teigha library 9 10OGR supports reading most versions of AutoCAD DWG when built with the 11Open Design Alliance Teigha library. DWG is an binary working format used 12for AutoCAD drawings. A reasonable effort has been made to make the OGR 13DWG driver work similarly to the OGR DXF driver which shares a common 14data model. The entire contents of the .dwg file is represented as a 15single layer named "entities". 16 17DWG files are considered to have no georeferencing information through 18OGR. Features will all have the following generic attributes: 19 20- Layer: The name of the DXF layer. The default layer is "0". 21- SubClasses: Where available, a list of classes to which an element 22 belongs. 23- ExtendedEntity: Where available, extended entity attributes all 24 appended to form a single text attribute. 25- Linetype: Where available, the line type used for this entity. 26- EntityHandle: The hexadecimal entity handle. A sort of feature id. 27- Text: The text of labels. 28 29A reasonable attempt is made to preserve line color, line width, text 30size and orientation via OGR feature styling information when 31translating elements. Currently no effort is made to preserve fill 32styles or complex line style attributes. 33 34The approximation of arcs, ellipses, circles and rounded polylines as 35linestrings is done by splitting the arcs into subarcs of no more than a 36threshold angle. This angle is the OGR_ARC_STEPSIZE. This defaults to 37four degrees, but may be overridden by setting the configuration 38variable OGR_ARC_STEPSIZE. 39 40DWG_INLINE_BLOCKS 41----------------- 42 43The default behavior is for block references to be expanded with the 44geometry of the block they reference. However, if the DWG_INLINE_BLOCKS 45configuration option is set to the value FALSE, then the behavior is 46different as described here. 47 48- A new layer will be available called blocks. It will contain one or 49 more features for each block defined in the file. In addition to the 50 usual attributes, they will also have a BlockName attribute indicate 51 what block they are part of. 52- The entities layer will have new attributes BlockName, BlockScale, 53 and BlockAngle. 54- block referenced will populate these new fields with the 55 corresponding information (they are null for all other entities). 56- block references will not have block geometry inlined - instead they 57 will have a point geometry for the insertion point. 58 59The intention is that with DWG_INLINE_BLOCKS disabled, the block 60references will remain as references and the original block definitions 61will be available via the blocks layer. 62 63Building 64-------- 65 66See :ref:`ODA platform support <vector.oda>` for building GDAL with ODA support.