Merge pull request #1737 from adrianVmariano/master

vnf bugfix & doc tweaks

skin.scad

@@ -1311,7 +1311,7 @@ function rotate_sweep(
                   : tex_reps,
          tex_depth = is_def(tex_scale)? echo("In rotate_sweep() the 'tex_scale' parameter is deprecated and has been replaced by 'tex_depth'")tex_scale
                    : default(tex_depth,1),
-         region = force_region(shape)
+         region = _force_xplus(force_region(shape))
     )
     assert(is_region(region), "\nshape is not a region or path.")
     let(
@@ -1360,6 +1360,9 @@ function rotate_sweep(
     ) vnf;
 
 
+function _force_xplus(data) =
+  [for(part=data) [for(pt=part) approx(pt.x,0) ? [0,pt.y] : pt]];
+
 module rotate_sweep(
     shape, angle=360,
     texture, tex_size=[5,5], tex_counts, tex_reps,
@@ -1388,7 +1391,7 @@ module rotate_sweep(
              : tex_reps;
     tex_depth = is_def(tex_scale)? echo("In rotate_sweep() the 'tex_scale' parameter is deprecated and has been replaced by 'tex_depth'")tex_scale
               : default(tex_depth,1);
-    region = force_region(shape);
+    region = _force_xplus(force_region(shape));
     check = assert(is_region(region), "\nInput is not a region or polygon.");
     bounds = pointlist_bounds(flatten(region));
     min_x = bounds[0].x;

turtle3d.scad

@@ -31,10 +31,16 @@ function _rotpart(T) = [for(i=[0:3]) [for(j=[0:3]) j<3 || i==3 ? T[i][j] : 0]];
 // Description:
 //   Like the classic two dimensional turtle, the 3d turtle flies through space following a sequence
 //   of turtle graphics commands to generate either a sequence of transformations (suitable for input
-//   to {{sweep()}}) or a 3d path.  The turtle state keeps track of the position and orientation (including twist)
+//   to {{sweep()}}) or a 3d path.
+//   .
+//   The turtle state keeps track of the position and orientation (including twist)
 //   and scale of the turtle.  By default the turtle begins pointing along the X axis with the "right" direction
 //   along the -Y axis and the "up" direction aligned with the Z axis.  You can give a direction vector
-//   for the state input to change the starting direction.  Because of the complexity of object positioning
+//   for the state input to change the starting direction.  You can also give a transformation for the state.
+//   For example, if you want the turtle to start its trajectory at the coordinate [3,4,5] you could
+//   give `state=move([3,4,5])`.
+//   .
+//   Because of the complexity of object positioning
 //   in three space, some types of movement require compound commands.  These compound commands are lists that specify several operations
 //   all applied to one turtle step.  For example:  ["move", 4, "twist", 25] executes a twist while moving, and
 //   the command ["arc", 4, "grow", 2, "right", 45, "up", 30] turns to the right and up while also growing the object.
@@ -163,7 +169,7 @@ function _rotpart(T) = [for(i=[0:3]) [for(j=[0:3]) j<3 || i==3 ? T[i][j] : 0]];
 //   the results are very strange if larger angles are permitted.)
 // Arguments:
 //   commands = List of turtle3d commands
-//   state = Starting turtle direction or full turtle state (from a previous call).  Default: RIGHT
+//   state = Starting turtle direction, starting turtle transformation (e.g. move(pt)), or full turtle state (from a previous call).  Default: RIGHT
 //   transforms = If true teturn list of transformations instead of points.  Default: false
 //   full_state = If true return full turtle state for continuing the path in subsequent turtle calls.  Default: false
 //   repeat = Number of times to repeat the command list.  Default: 1

tutorials/Attachment-Parts.md

@@ -1,6 +1,6 @@
 [Prev: Using attach()](Tutorial-Attachment-Attach)
 
-# Attachment Parts
+# Attachable Parts
 
 Some objects provide named attachable parts that you can select
 instead of using the main geometry for the object.  One important kind

vnf.scad

@@ -40,15 +40,18 @@ EMPTY_VNF = [[],[]];  // The standard empty VNF with no vertices or faces.
 //   and creating the faces defined by those edges.  You can optionally create the edges and faces to wrap the last column
 //   back to the first column, or wrap the last row to the first.  Endcaps can be added to either
 //   the first and/or last rows.  The style parameter determines how the quadrilaterals are divided into
-//   triangles.  The default style is an arbitrary, systematic subdivision in the same direction.  The "alt" style
+//   triangles.  The styles are:
-//   is the uniform subdivision in the other (alternate) direction.  The "flip1" style is an arbitrary division that alternates the
+//   * "default" — arbitrary, systematic subdivision in the same direction
-//   direction for any adjacent pair of quadrilaterals.  The "flip2" style is the alternating division that is the opposite of "flip1". 
+//   * "alt" — uniform subdivision in the other (alternate) direction
-//   The "min_edge" style picks the shorter edge to
+//   * "flip1" — arbitrary division that alternates the direction adjacent pairs of quadrilaterals.
-//   subdivide for each quadrilateral, so the division may not be uniform across the shape.  The "quincunx" style
+//   * "flip2" — the alternating division that is the opposite of "flip1". 
-//   adds a vertex in the center of each quadrilateral and creates four triangles, and the "convex" and "concave" styles
+//   * "min_edge" — subdivide each quadrilateral on its shorter edge, so the division may not be uniform across the shape
-//   choose the locally convex/concave subdivision.  The "min_area" option creates the triangulation with the minimal area.
+//   * "min_area" — creates the triangulation with the minimal area.
-//   The "quad" style makes quadrilateral edges, which may not be coplanar, relying on OpensCAD to decide how to handle them.  Degenerate faces
+//   * "quincunx" — adds a vertex in the center of each quadrilateral and creates four triangles
-//   are not included in the output, but if this results in unused vertices, those unused vertices do still appear in the output.
+//   * "convex" — choose the locally convex division
+//   * "concave" — choose the locally concave division
+//   * "quad" — makes quadrilateral edges, which may not be coplanar, relying on OpensCAD to decide how to handle them.
+// Degenerate faces are not included in the output, but if this results in unused vertices, those unused vertices do still appear in the output.
 //   .
 //   You can apply a texture to the vertex array VNF using the usual texture parameters.
 //   See [Texturing](skin.scad#section-texturing) for more details on how textures work.  
@@ -388,9 +391,6 @@ function vnf_vertex_array(
                         style=="quincunx"?
                           let(i5 = pcnt + r*colcnt + c)
                           [[i1,i5,i2],[i2,i5,i3],[i3,i5,i4],[i4,i5,i1]]
-                      : style=="alt" || (style=="flip1" && ((r+c)%2==0)) || (style=="flip2" && ((r+c)%2==1)) || (style=="random" && rands(0,1,1)[0]<.5)?
-                          [[i1,i4,i2],[i2,i4,i3]]
-                      : style=="default" ? [[i1,i3,i2],[i1,i4,i3]]
                       : style=="min_area"?
                           let(
                                area42 = norm(cross(pts[i2]-pts[i1], pts[i4]-pts[i1]))+norm(cross(pts[i4]-pts[i3], pts[i2]-pts[i3])),
@@ -429,7 +429,10 @@ function vnf_vertex_array(
                                     : [[i1,i3,i2],[i1,i4,i3]]
                           )
                           concavefaces
-                      : [[i1,i2,i3,i4]],
+                      : style=="quad" ? [[i1,i2,i3,i4]]
+                      : style=="alt" || (style=="flip1" && ((r+c)%2==0)) || (style=="flip2" && ((r+c)%2==1)) || (style=="random" && rands(0,1,1)[0]<.5)?
+                          [[i1,i4,i2],[i2,i4,i3]]
+                      : [[i1,i3,i2],[i1,i4,i3]],
                    // remove degenerate faces
                    culled_faces= [for(face=faces)
                        if (norm(cross(verts[face[1]]-verts[face[0]],