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doc tweak for spheroid

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Adrian Mariano 2022-02-03 19:10:25 -05:00
parent d6b4d48aa2
commit fc61faeec3
1 changed files with 9 additions and 6 deletions
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15
shapes3d.scad
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@ -1658,7 +1658,7 @@ function sphere(r, d, circum=false, style="orig", anchor=CENTER, spin=0, orient=
// - `style="icosa"` forms a sphere by subdividing an icosahedron. This makes even more uniform faces over the whole sphere. The effective `$fn` value is quantized to a multiple of 5. This sphere has a guaranteed bounding box when `$fn` is a multiple of 10.
// .
// By default the object spheroid() produces is a polyhedron whose vertices all lie on the requested sphere. This means
// it is an inscribed sphere, which sits inside the requested sphere.
// the approximating polyhedron is inscribed in the sphere.
// The `circum` argument requests a circumscribing sphere, where the true sphere is
// inside and tangent to all the faces of the approximating polyhedron. To produce
// a circumscribing polyhedron, we use the dual polyhedron of the basic form. The dual of a polyhedron is
@ -1667,16 +1667,19 @@ function sphere(r, d, circum=false, style="orig", anchor=CENTER, spin=0, orient=
// these styles then the polyhedron will look the same as the default inscribing form. But for the other
// styles, the duals are completely different from their parents, and from each other. Generation of the circumscribed versions (duals)
// for "octa" and "icosa" is fast if you use the module form but can be very slow (several minutes) if you use the functional
// form and choose a large $fn value. With style="align", the circumscribed sphere has its maximum radius on the X and Y axes
// but is undersized on the Z axis. With style="octa" the circumscribed sphere has faces at each axis, so the radius equals
// the specified radius, but other points on the object are farther from the origin. The same situation applies to "icosa" when
// $fn is a multiple of 10.
// form and choose a large $fn value.
// .
// With style="align", the circumscribed sphere has its maximum radius on the X and Y axes
// but is undersized on the Z axis. With style="octa" the circumscribed sphere has faces at each axis, so
// the radius on the axes is equal to the specified radius, which is the *minimum* radius of the circumscribed sphere.
// The same thing is true for style="icosa" when $fn is a multiple of 10. This would enable you to create spherical
// holes with guaranteed on-axis dimensions.
// Arguments:
// r = Radius of the spheroid.
// style = The style of the spheroid's construction. One of "orig", "aligned", "stagger", "octa", or "icosa". Default: "aligned"
// ---
// d = Diameter of the spheroid.
// circum = If true, the spheroid is produced in a style where it circumscribes the sphere of the requested size. Otherwise inscribes. Note that for some styles, the circumscribed sphere looks different than the inscribed sphere. Default: false (inscribes)
// circum = If true, the approximate sphere circumscribes the true sphere of the requested size. Otherwise inscribes. Note that for some styles, the circumscribed sphere looks different than the inscribed sphere. Default: false (inscribes)
// anchor = Translate so anchor point is at origin (0,0,0). See [anchor](attachments.scad#subsection-anchor). Default: `CENTER`
// spin = Rotate this many degrees around the Z axis after anchor. See [spin](attachments.scad#subsection-spin). Default: `0`
// orient = Vector to rotate top towards, after spin. See [orient](attachments.scad#subsection-orient). Default: `UP`