tweaked vac example in turtle3d

added delete_last() to arrays.scad
added endpoint= option to arc
added tests for last two things

arrays.scad

@@ -101,6 +101,15 @@ function select(list, start, end=undef) =
 //   last(l);  // Returns 9.
 function last(list) = list[len(list)-1];
 
+// Function: delete_last()
+// Description:
+//   Returns a list of all but the last entry.  If input is empty, returns empty list.
+// Usage:
+//   delete_last(list)
+function delete_last(list) =
+   assert(is_list(list))
+   list==[] ? [] : slice(list,0,-2);
+
 // Function: slice()
 // Description:
 //   Returns a slice of a list.  The first item is index 0.
@@ -281,7 +290,7 @@ function list_range(n=undef, s=0, e=undef, step=undef) =
 // Example:
 //   reverse([3,4,5,6]);  // Returns [6,5,4,3]
 function reverse(x) =
-    assert(is_list(x)||is_string(x))
+    assert(is_list(x)||is_string(x), "Input to reverse must be a list or string")
     let (elems = [ for (i = [len(x)-1 : -1 : 0]) x[i] ])
     is_string(x)? str_join(elems) : elems;
 

shapes2d.scad

@@ -350,7 +350,7 @@ module stroke(
 //   N = Number of vertices to form the arc curve from.
 //   r = Radius of the arc.
 //   d = Diameter of the arc.
-//   angle = If a scalar, specifies the end angle in degrees.  If a vector of two scalars, specifies start and end angles.
+//   angle = If a scalar, specifies the end angle in degrees (relative to start parameter).  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
@@ -360,6 +360,7 @@ module stroke(
 //   thickness = If given with `width`, arc starts and ends on X axis, to make a circle segment.
 //   start = Start angle of arc.
 //   wedge = If true, include centerpoint `cp` in output to form pie slice shape.
+//   endpoint = If false exclude the last point (function only).  Default: true
 // Examples(2D):
 //   arc(N=4, r=30, angle=30, wedge=true);
 //   arc(r=30, angle=30, wedge=true);
@@ -378,7 +379,10 @@ module stroke(
 // Example(FlatSpin):
 //   path = arc(points=[[0,30,0],[0,0,30],[30,0,0]]);
 //   trace_path(path, showpts=true, color="cyan");
-function arc(N, r, angle, d, cp, points, width, thickness, start, wedge=false, long=false, cw=false, ccw=false) =
+function arc(N, r, angle, d, cp, points, width, thickness, start, wedge=false, long=false, cw=false, ccw=false, endpoint=true) =
+    assert(is_bool(endpoint))
+    !endpoint ? assert(!wedge, "endpoint cannot be false if wedge is true")
+               slice(arc(N,r,angle,d,cp,points,width,thickness,start,wedge,long,cw,ccw,true),0,-2) :
     // First try for 2D arc specified by width and thickness
     is_def(width) && is_def(thickness)? (
                 assert(!any_defined([r,cp,points]) && !any([cw,ccw,long]),"Conflicting or invalid parameters to arc")
@@ -472,7 +476,7 @@ function _normal_segment(p1,p2) =
 
 // Function: turtle()
 // Usage:
-//   turtle(commands, [state], [full_state], [repeat])
+//   turtle(commands, [state], [full_state], [repeat], [endpoint])
 // Description:
 //   Use a sequence of turtle graphics commands to generate a path.  The parameter `commands` is a list of
 //   turtle commands and optional parameters for each command.  The turtle state has a position, movement direction,

tests/test_arrays.scad

@@ -27,6 +27,21 @@ module test_select() {
 }
 test_select();
 
+module test_last() {
+    list = [1,2,3,4];
+    assert(last(list)==4);
+    assert(last([])==undef);
+}
+test_last();
+
+module test_delete_last() {
+    list = [1,2,3,4];
+    assert(delete_last(list) == [1,2,3]);
+    assert(delete_last([1]) == []);
+    assert(delete_last([]) == []);
+}
+test_delete_last();
+
 
 module test_slice() {
     assert(slice([3,4,5,6,7,8,9], 3, 5) == [6,7]);

tests/test_shapes2d.scad

@@ -40,6 +40,7 @@ test_turtle();
 
 module test_arc() {
     assert_approx(arc(N=8, d=100, angle=135, cp=[10,10]), [[60,10],[57.1941665154,26.5139530978],[49.0915741234,41.1744900929],[36.6016038258,52.3362099614],[21.1260466978,58.7463956091],[4.40177619483,59.6856104947],[-11.6941869559,55.0484433951],[-25.3553390593,45.3553390593]]);
+    assert_approx(arc(N=8, d=100, angle=135, cp=[10,10],endpoint=false), [[60,10],[57.1941665154,26.5139530978],[49.0915741234,41.1744900929],[36.6016038258,52.3362099614],[21.1260466978,58.7463956091],[4.40177619483,59.6856104947],[-11.6941869559,55.0484433951],[-25.3553390593]]);    
     assert_approx(arc(N=8, d=100, angle=[45,225], cp=[10,10]), [[45.3553390593,45.3553390593],[26.5139530978,57.1941665154],[4.40177619483,59.6856104947],[-16.6016038258,52.3362099614],[-32.3362099614,36.6016038258],[-39.6856104947,15.5982238052],[-37.1941665154,-6.51395309776],[-25.3553390593,-25.3553390593]]);
     assert_approx(arc(N=8, d=100, start=45, angle=135, cp=[10,10]), [[45.3553390593,45.3553390593],[31.6941869559,55.0484433951],[15.5982238052,59.6856104947],[-1.12604669782,58.7463956091],[-16.6016038258,52.3362099614],[-29.0915741234,41.1744900929],[-37.1941665154,26.5139530978],[-40,10]]);
     assert_approx(arc(N=8, d=100, start=45, angle=-90, cp=[10,10]), [[45.3553390593,45.3553390593],[52.3362099614,36.6016038258],[57.1941665154,26.5139530978],[59.6856104947,15.5982238052],[59.6856104947,4.40177619483],[57.1941665154,-6.51395309776],[52.3362099614,-16.6016038258],[45.3553390593,-25.3553390593]]);

turtle3d.scad

@@ -360,7 +360,7 @@ function _rotpart(T) = [for(i=[0:3]) [for(j=[0:3]) j<3 || i==3 ? T[i][j] : 0]];
 //                       ["move", seg1_len, "grow", seg1_bot_ID/seg2_bot_ID]
 //                    ],
 //                    state=UP, transforms=true);
-//   zrot(90)back_half()      // Remove this to get a usable part
+//   back_half()      // Remove this to get a usable part
 //     sweep(circle(d=seg1_bot_OD, $fn=128), trans, closed=true);
 // Example: Closed spiral
 //   include<BOSL2/skin.scad>