A Custom Drawing Projections Tool
Back in 2007 I developed a software tool that could generate technical drawings in a range of drawing projections from a 3D model with emphasis on oblique (both cabinet and cavalier, as well as custom obliques), planometric, dimetric, trimetric and one-point perspective.
I could describe them all as well as many more in terms of what the projected three axis look like on the projection plane. I described them all in terms of a scale on each of the three axis, as well as the angle two of the axis make with the projection plane’s horizontal.
In terms of the actual development of the program I’m sure I could have done things a lot better. But I did learn a lot from the experience. The program worked to my needs and did what I wrote it to do so in that sense it was a success. The only downside would be that I did a lot of code rewriting of code that already existed out there (which probably did thinks better than I implemented them). Although since then I have done much more programming and had formal training so have learnt about better methods and practices.
The approach I took was basically import a DXF file, process the data to change its projection, and then export it as a DXF again. I used 3D polylines generated from my 3D model in Rhino and saved as DXF for the input. So I had to write a cutdown DXF reader/writer, as well as a way of storing this data internally and then doing the transformations on it then exporting it back into DXF so I could open it up in AutoCAD.
I only supported points, polylines, circles and arcs as this is basically all that Rhino exported from my model. To simplify the process of circles and arcs I internally converted them to a bunch of polylines as only for some projections they stayed as nice ellipses.
From a very simple model in Rhino, I use the silhouette tool to create the polylines which once impororted into my program produced the following samples.
There is also a range of built in axonometric projections…