Drawing a dxf cylinder
Moderator: andrew
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Drawing a dxf cylinder
I have a cylinder in parametric form, that I want to draw as a dxf. What would be the optimal way of doing this with dxflib? Using polygons? NURBS? I am new to AutoCAD and not sure about the ways I can do this. I tried creating a cylinder in AutoCAD 2014 and exporting it to DXF and it only creates two circles, with the base and top part of the cylinder. Also, it looks like it cannot be rotated...
Re: Drawing a dxf cylinder
dxflib is mostly suitable for 2D content. We use it for the free community edition of QCAD (also 2D).
3D content might be achievable using extrusion. Please note that not every viewer / CAD system supports these. QCAD being 2D doesn't.
3D content might be achievable using extrusion. Please note that not every viewer / CAD system supports these. QCAD being 2D doesn't.
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Re: Drawing a dxf cylinder
Thanks a lot for your anwser andrew. So are you saying that dxflib is not capable of achieving what I want or that the result will not be compatible with every viewer? I am OK with the second, I don't need full compatibility. If indeed would be possible to use extrusion with dxflib, could you point me in the right direction, so I can try to experiment a little bit (what entities I need to use, etc.)?
Re: Drawing a dxf cylinder
dxflib does currently not support writing extrusions. Support could be added relatively easily in DL_Writer::entityAttributes.
Note that even if you have extrusion support, you won't be able to create a cylinder that is rotated in 3D space (extrusions are parallel to the X/Y plane).
Note that even if you have extrusion support, you won't be able to create a cylinder that is rotated in 3D space (extrusions are parallel to the X/Y plane).
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Re: Drawing a dxf cylinder
I would not mind adding extrusions myself and contributing to the project, but I would need to be able to rotate the resulting primitive. Can this be achieved using dxf?
Re: Drawing a dxf cylinder
Not 100% sure, but I think you'd have to use a 3DSOLID entity to represent such a body.XxOsurfer3xX wrote:Can this be achieved using dxf?
3DSOLID entities are available in DXF but consist of proprietary, binary, undocumented data.
I'd recommend to find a 3D CAD application, create the type of cylinder you need, export it to DXF and cross-check the result with a 3D DXF viewer. The DXF file reveals what entity can be used best to represent such a body.
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Re: Drawing a dxf cylinder
I have been looking at DXF documentation and in the circle entity I can see:
210
Extrusion direction (optional; default = 0, 0, 1)
DXF: X value; APP: 3D vector
220, 230
DXF: Y and Z values of extrusion direction (optional)
Wouldn't that let me extrude in any direction I want?
210
Extrusion direction (optional; default = 0, 0, 1)
DXF: X value; APP: 3D vector
220, 230
DXF: Y and Z values of extrusion direction (optional)
Wouldn't that let me extrude in any direction I want?
Re: Drawing a dxf cylinder
You'd have to try it:XxOsurfer3xX wrote:Wouldn't that let me extrude in any direction I want?
Export a circle to DXF
Add the extrusion vector manually
Load the resulting DXF file in a 3D viewer
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Re: Drawing a dxf cylinder
Ok, I'll go ahead and try. I'll keep you updated with the results. Thanks a lot for your help.
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Re: Drawing a dxf cylinder
I can confirm it is possible to create a 3D cylinder extruding a circle, using extrusion direction and thickness. The main problem is that when using a extrusion direction different from the default one (0,0,1), the object appears in different coordinates, as if the UCS was changed... Anyone knows why can this be happening? In the upcoming weeks I'll try to make it work with dxflib, and see what happens...