[OpenSCAD] trying to modify Sweep

nop head nop.head at gmail.com
Tue Jan 2 16:20:14 EST 2018


You can't pass functions in OpenSCAD. You are simply passing in the result
of calling the function with no argument. So inside sweep it has no access
to shape().

On 2 January 2018 at 21:15, jon <jon at jonbondy.com> wrote:

> I'm trying to do something that seems conceptually simple to me, but it
> keeps failing.
>
> Rather than passing a parameter-less shape() function into sweep(), I am
> passing a function with one parameter, the scale. This should allow me to
> use a circular cross section to create a snake-that-swallowed-a-grapefruit
> shape, by varying the scale dynamically.
>
> In the implementation of sweep() I changed this function, as follows (I
> calculate to_3d() of the shape() each time):
>
>     function sweep_points() = flatten([for (i=[0:pathlen])
> transform(path_transforms[i], to_3d(shape(i)))]);
>
> I renamed sweep.scad to be sweep-jon.scad.  While sweep-jon.scad compiles
> without errors, the invocation code (below) fails with"Ignoring unknown
> function 'shape'" and then "PolySet has degenerate polygons".
>
> What am I missing?
>
>
> use <sweep-Jon.scad>
>
> function f(a) = [18*sin(360*a), 18-18*cos(360*a*0.7), 36*sin(360*a/2)];
>
> function shape(d) =
>     [for (i=[1:10:360]) [d*sin(i), d*cos(i)]];
>
> step = 0.005;
> path = [for (t=[0:step:1-step]) f(t)];
> path_transforms = construct_transform_path(path);
> sweep(shape(), path_transforms);
>
> --
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>
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