you are not working with the centre of the svg, afaik

On 09/07/2024 10:08, Gábor Magyar via Discuss wrote:

On Tue, 2024-07-09 at 11:08 +0200, Gábor Magyar via Discuss wrote:

Your attachment shows a figure that has been rotated and placed around
what appears to be an equal radius from the origin.

Is that figure the SVG you are speaking of? If so, what is the problem
with it?

Could you attach a copy of the SVG you are working with?

On Tue, 2024-07-09 at 11:08 +0200, Gábor Magyar via Discuss wrote:

Assuming you want to rotate the svg to keep its orientation the same in
all positions, here's a small modification of code you have been
previously given:

<<code>>

include <BOSL2/std.scad>
$fn=60;

cylinder(d=400,h=1);
color("red")
zrot_copies(n=12,sa=90,d=300,subrot=false)
svg();

module svg() {
translate([ -70.426 , -236 , 0 ])
linear_extrude(2) import("/home/larry/Desktop/symbol.svg");
}

<<code>>

When supplying an example, please make sure that it is self-contained. 
This one needs the SVG file to work, and does not include definitions
for r_, d_, and h_.

Those missing parts limit how much I can analyze the program.

Are you getting error messages in the console pane or in the error log
pane?  After I supply a dummy module replacing the missing SVG file, I
get 47 errors.

I do see a couple of things.

x-x is equal to zero, so these are translating by zero in X.

A cylinder is a circle in the XY plane, extended vertically in Z. 
You've asked it to rotate around the Z axis... which (mostly) won't do
anything to a circle or cylinder.  (For a low-resolution
circle/cylinder, it will re-orient the edges/faces.  But you don't seem
to be trying to do that.)

You're placing four copies of the SVG.  The first is rotated -3 times 5
= 15, divided by 12 = +1.25 degrees, or nearly nothing, then translated
a ways out in +Y, then rotated -3 times 360 = 1080, divided by 12 = -90
degrees, for a net of rotating by -88.75 degrees.  The second is rotated
0.833 degrees, translated, and then rotated -60, for a net of -59.167
degrees.  The third is rotated +0.417, then -30, net -29.58.  The fourth
is rotated zero, translated,  and then rotated zero.

If you're trying to position a symbol at points around the circle,
maintaining its rotation, you want the two rotates to be for the same
value, but negated.  You probably want

for(i = [-3:0])
rotate(i * 360 /12)
translate(...)
rotate(-i * 360 /12)
import(svg);

And although it's mathematically equivalent, I think it's more
understandable to describe that rotation using the division first, so
that you calculate a fraction around the circle, and then multiply by
360 to get the number of degrees, so:

rotate(i / 12 * 360)

Going back to the translate for a moment, I think you mean

translate([-svg_[0]/2, d_ - svg_[1]/2])

so as to center the SVG and position it out to "d_".  HOWEVER, I think
that's still not right, because it's happening after the first rotate,
and you probably want to center it before the first rotate so that
you're rotating around the center of the SVG, so you want to split the
centering part away from the "move out d_" part.

Net, I think you probably want:

  for(i = [-3:0])
    rotate(i /12 * 360)
      translate([0, d_])
        rotate(-i /12 * 360)
          translate([-svg_[0]/2, -svg_[1]/2])
            import(svg);

But... SVG positioning is strange for a number of reasons, so that might
not be quite right.  Still, you probably want the translate innermost,
to get the object centered before you start messing with it.  Put an
exclamation point before the translate() so that OpenSCAD displays just
that one object, and play with the translate values until it's centered.

On Tue, 2024-07-09 at 23:25 +0000, Jordan Brown via Discuss wrote:

I suppose I too should have provided the svg example in my response,
but it's just an svg I whipped up in Inkscape. Its only reason for
being sit that it's easy to see the rotations.

If I were doing it, I'd impport the svg, render it, and export it as an
stl. I would then use stlplace, available on github.

https://github.com/lar3ry/OpenSCAD---Move-STL-to-origin

That will centre it, and BOSL2 makes short work of it.