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Added long, cw, and ccw arguments to arc for selecting which arc is

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drawn when you give 2 points and a centerpoint.
This commit is contained in:
Adrian Mariano 2020-05-25 23:43:52 -04:00
parent 4eda2c701e
commit 9fe8788357
1 changed files with 11 additions and 5 deletions
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16
shapes2d.scad
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@ -341,6 +341,9 @@ module stroke(
// angle = If a scalar, specifies the end angle in degrees. If a vector of two scalars, specifies start and end angles.
// cp = Centerpoint of arc.
// points = Points on the arc.
// long = if given with cp and points takes the long arc instead of the default short arc. Default: false
// cw = if given with cp and 2 points takes the arc in the clockwise direction. Default: false
// ccw = if given with cp and 2 points takes the arc in the counter-clockwise direction. Default: false
// width = If given with `thickness`, arc starts and ends on X axis, to make a circle segment.
// thickness = If given with `width`, arc starts and ends on X axis, to make a circle segment.
// start = Start angle of arc.
@ -363,7 +366,7 @@ module stroke(
// Example(FlatSpin):
// path = arc(points=[[0,30,0],[0,0,30],[30,0,0]]);
// trace_polyline(path, showpts=true, color="cyan");
function arc(N, r, angle, d, cp, points, width, thickness, start, wedge=false) =
function arc(N, r, angle, d, cp, points, width, thickness, start, wedge=false, long=false, cw=false, ccw=false) =
// First try for 2D arc specified by angles
is_def(width) && is_def(thickness)? (
arc(N,points=[[width/2,0], [0,thickness], [-width/2,0]],wedge=wedge)
@ -384,7 +387,7 @@ function arc(N, r, angle, d, cp, points, width, thickness, start, wedge=false) =
)
concat(extra,arcpoints)
) :
assert(is_list(points),"Invalid parameters")
assert(is_path(points,[2,3]),"Point list is invalid")
// Arc is 3D, so transform points to 2D and make a recursive call, then remap back to 3D
len(points[0])==3? (
let(
@ -396,15 +399,18 @@ function arc(N, r, angle, d, cp, points, width, thickness, start, wedge=false) =
) : is_def(cp)? (
// Arc defined by center plus two points, will have radius defined by center and points[0]
// and extent defined by direction of point[1] from the center
let(
assert(count_true([long,cw,ccw])<=1, str("Only one of `long`, `cw` and `ccw` can be true",cw,ccw,long))
let( k=echo(cw=cw,ccw=ccw,long=long),
angle = vector_angle(points[0], cp, points[1]),
v1 = points[0]-cp,
v2 = points[1]-cp,
dir = sign(det2([v1,v2])), // z component of cross product
r=norm(v1)
r=norm(v1),
long = long || (ccw && dir<0) || (cw && dir>0)
,ewqe=echo(long=long,angle=dir*angle,start=atan2(v1.y,v1.x),angle=long?-dir*(360-angle):dir*angle)
)
assert(dir!=0,"Collinear inputs don't define a unique arc")
arc(N,cp=cp,r=r,start=atan2(v1.y,v1.x),angle=dir*angle,wedge=wedge)
arc(N,cp=cp,r=r,start=atan2(v1.y,v1.x),angle=long?-dir*(360-angle):dir*angle,wedge=wedge)
) : (
// Final case is arc passing through three points, starting at point[0] and ending at point[3]
let(col = collinear(points[0],points[1],points[2]))