You have to describe with SVG path syntax a closed shape that is within a 1 unit wide square.
To find the good shape for the spiral staircase in the default catalog, I added this staircase to the plan, resized it to 1meter wide and 1meter deep and placed it on the grid in a way it touches a meter grid line (of course you'll have to chose metric system in the preferences).
Then I measured the points of the cut out shape and described it with SVG path syntax (the syntax isn't very easy to understand but the previous link gives many examples to guide you).
Describing the shape of a pie is quite tedious and finding the right values of the shape of the spiral staircase took me several minutes:
M0,0.35 h0.47 l0.375,-0.35 l0.088,0.118 A0.5,0.5 0 1,1 0,0.35 zBut describing a polygonal shape should be much easier. For example, the following expression describes a L shape:
M0,0 h0.5 v0.5 h0.5 v0.5 h-1 zDon't forget to close the shape with a final z and pay attention to the difference between upper case letter (followed by absolute coordinate values) and lower case letter (followed by coordinate values relative to the previous move) syntax.
Hope you can handle it.
Merry Christmas
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Emmanuel Puybaret, Sweet Home 3D creator
