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Added support for chamfered offsets to offset_sweep.

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Adrian Mariano 2020-01-25 00:40:03 -05:00
parent 07e111489c
commit f449093034
1 changed files with 20 additions and 5 deletions
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25
rounding.scad
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@ -444,7 +444,7 @@ function _rounding_offsets(edgespec,z_dir=1) =
// - quality: passed to offset(). Default: 1
// - steps: Number of vertical steps to use for the profile. (Not used by os_profile). Default: 16
// - offset_maxstep: The maxstep distance for offset() calls; controls the horizontal step density. Set smaller if you don't get the expected rounding. Default: 1
// - offset: Select "round" (r=) or "delta" (delta=) offset types for offset. Default: "round"
// - offset: Select "round" (r=) or "delta" (delta=) offset types for offset. You can also choose "chamfer" but this leads to exponential growth in the number of vertices with the steps parameter. Default: "round"
//
// Many of the arguments are described as setting "default" values because they establish settings which may be overridden by
// the top and bottom profile specifications.
@ -465,7 +465,15 @@ function _rounding_offsets(edgespec,z_dir=1) =
// - "quality" - passed to offset. Default: 1.
// - "steps" - number of vertical steps to use for the roundover. Default: 16.
// - "offset_maxstep" - maxstep distance for offset() calls; controls the horizontal step density. Set smaller if you don't get expected rounding. Default: 1
// - "offset" - select "round" (r=) or "delta" (delta=) offset type for offset. Default: "round"
// - "offset" - select "round" (r=), "delta" (delta=), or "chamfer" offset type for offset. Default: "round"
//
// Note that if you set the "offset" parameter to "chamfer" then every exterior corner turns from one vertex into two vertices with
// each offset operation. Since the offsets are done one after another, each on the output of the previous one, this leads to
// exponential growth in the number of vertices. This can lead to long run times or yield models that
// run out of recursion depth and give a cryptic error. Furthermore, the generated vertices are distributed non-uniformly. Generally you
// will get a similar or better looking model with fewer vertices using "round" instead of
// "chamfer". Use the "chamfer" style offset only in cases where the number of steps is very small or just one (such as when using
// the `os_chamfer` profile type).
//
// Arguments:
// path = 2d path (list of points) to extrude
@ -613,13 +621,14 @@ module offset_sweep(
) : (
let(
this_offset = offsetind==0? offsets[0][0] : offsets[offsetind][0] - offsets[offsetind-1][0],
delta = offset_type=="delta"? this_offset : undef,
r = offset_type=="round"? this_offset : undef
delta = offset_type=="delta" || offset_type=="chamfer" ? this_offset : undef,
r = offset_type=="round"? this_offset : undef,
do_chamfer = offset_type == "chamfer"
)
assert(num_defined([r,delta])==1,"Must set `offset` to \"round\" or \"delta")
let(
vertices_faces = offset(
path, r=r, delta=delta, closed=true,
path, r=r, delta=delta, chamfer = do_chamfer, closed=true,
check_valid=check_valid, quality=quality,
maxstep=maxstep, return_faces=true,
firstface_index=vertexcount,
@ -673,6 +682,9 @@ module offset_sweep(
offsets_bot = _rounding_offsets(bottom, -1);
offsets_top = _rounding_offsets(top, 1);
if (offset == "chamfer" && (len(offsets_bot)>5 || len(offsets_top)>5)) {
echo("WARNING: You have selected offset=\"chamfer\", which leads to exponential growth in the vertex count and requested many layers. This can be slow or run out of recursion depth.");
}
// "Extra" height enlarges the result beyond the requested height, so subtract it
bottom_height = len(offsets_bot)==0 ? 0 : abs(select(offsets_bot,-1)[1]) - struct_val(bottom,"extra");
top_height = len(offsets_top)==0 ? 0 : abs(select(offsets_top,-1)[1]) - struct_val(top,"extra");
@ -845,6 +857,9 @@ function os_profile(points, extra,check_valid, quality, offset_maxstep, offset)
// - "steps" - number of vertical steps to use for the roundover. Default: 16.
// - "offset" - select "round" (r=) or "delta" (delta=) offset type for offset. Default: "round"
//
// Note that unlike `offset_sweep`, because the offset operation is always performed from the base shape, using chamfered offsets does not increase the
// number of vertices or lead to any special complications.
//
// Arguments:
// height / l / h = total height (including rounded portions, but not extra sections) of the output. Default: combined height of top and bottom end treatments.
// top = rounding spec for the top end.