Support for twisted cables.

Sweep now distbutes twists in proportion to segments lengths.
Added  spiral_paths(), segmented_path() and rounded_path_vertices() functions.
Added show_path(path) module.

CHANGELOG.md

@@ -3,6 +3,16 @@
 This changelog is generated by `changelog.py` using manually added semantic version tags to classify commits as breaking changes, additions or fixes.
 
 
+### [v19.6.0](https://github.com/nophead/NopSCADlib/releases/tag/v19.6.0 "show release") Additions [...](https://github.com/nophead/NopSCADlib/compare/v19.5.1...v19.6.0 "diff with v19.5.1")
+*   2022-02-06 [`225ea9b`](https://github.com/nophead/NopSCADlib/commit/225ea9b45160195bdf316e7ffdb383a63f898d3c "show commit") [C.P.](# "Chris Palmer") Added `rounded_path()` function to `sweep.scad`.
+
+#### [v19.5.1](https://github.com/nophead/NopSCADlib/releases/tag/v19.5.1 "show release") Fixes [...](https://github.com/nophead/NopSCADlib/compare/v19.5.0...v19.5.1 "diff with v19.5.0")
+*   2022-02-06 [`d341ce4`](https://github.com/nophead/NopSCADlib/commit/d341ce499e56972ff5267d3187387fe7df9d4130 "show commit") [C.P.](# "Chris Palmer") Added `render()` to `pocket_handle()`.
+
+*   2022-02-06 [`e7376e2`](https://github.com/nophead/NopSCADlib/commit/e7376e28c44355efa425b98aa0511ccdf0b63301 "show commit") [C.P.](# "Chris Palmer") Fixed corner block assembly names when overridden.
+
+*   2022-02-06 [`e238eaa`](https://github.com/nophead/NopSCADlib/commit/e238eaa473bac72136507d15c57f6156560d6cfe "show commit") [C.P.](# "Chris Palmer") Removed unused, undocumented function.
+
 ### [v19.5.0](https://github.com/nophead/NopSCADlib/releases/tag/v19.5.0 "show release") Additions [...](https://github.com/nophead/NopSCADlib/compare/v19.4.1...v19.5.0 "diff with v19.4.1")
 *   2022-02-01 [`04e94a8`](https://github.com/nophead/NopSCADlib/commit/04e94a859aa0d21f840c992b487a901f096790a4 "show commit") [C.P.](# "Chris Palmer") Added `earth_rot` parameter to `NEMA_screws()`.
 

readme.md

@@ -6565,6 +6565,12 @@ Subsequent rotations use the minimum rotation method.
 The path can be open or closed. If closed sweep ensures that the start and end have the same rotation to line up.
 An additional twist around the path can be specified. If the path is closed this should be a multiple of 360.
 
+`rounded_path()` can be used to generate a path of lines connected by arcs, useful for wire runs, etc.
+The vertices specify where the the path would be without any rounding.
+Each vertex, apart from the first and the last, has an associated radius and the path shortcuts the vertex with an arc specified by the radius.
+
+`spiral_paths()` makes a list of new paths that spiral around a given path. It can be used to make twisted wires that follow a rounded_path, for example.
+
 [utils/sweep.scad](utils/sweep.scad) Implementation.
 
 [tests/sweep.scad](tests/sweep.scad) Code for this example.
@@ -6580,12 +6586,17 @@ An additional twist around the path can be specified. If the path is closed this
 | `helical_twist_per_segment(r, pitch, sides)` | Calculate the twist around Z that rotate_from_to() introduces |
 | `path_length(path, i = 0, length = 0)` | Calculated the length along a path |
 | `rectangle_points(w, h)` | Generate the points of a rectangle |
+| `rounded_path(path)` | Convert a rounded_path, consisting of a start coordinate, vertex / radius pairs and then an end coordinate, to a path of points for sweep. |
+| `rounded_path_vertices(path)` | Show the unrounded version of a rounded_path for debug |
+| `segmented_path(path, min_segment)` | Add points to a path to enforce a minimum segment length |
 | `skin_faces(points, npoints, facets, loop, offset = 0)` | Create the mesh for the swept volume without end caps |
+| `spiral_paths(path, n, r, twists, start_angle)` | Create a new paths which sprial around the given path. Use for making twisted cables |
 | `sweep(path, profile, loop = false, twist = 0)` | Generate the point list and face list of the swept volume |
 
 ### Modules
 | Module | Description |
 |:--- |:--- |
+| `show_path(path)` | Show a path using a chain of hulls for debugging, duplicate points are highlighted. |
 | `sweep(path, profile, loop = false, twist = 0, convexity = 1)` | Draw a polyhedron that is the swept volume |
 
 ![sweep](tests/png/sweep.png)

tests/sweep.scad

@@ -32,22 +32,33 @@ loop_y = transform_points(loop, rotate([0, -90, $t * 360]));
 
 loop_z = transform_points(loop, rotate([$t * 360, 0, 0]));
 
-sweep(loop_z, L_points, loop = true);
+color("yellow") {
+    sweep(loop_z, L_points, loop = true);
 
-sweep(loop_x, L_points, loop = true);
-
-sweep(loop_y, L_points, loop = true);
+    sweep(loop_x, L_points, loop = true);
 
+    sweep(loop_y, L_points, loop = true);
+}
 
 knot = [ for(i=[0:.2:359])
          [ (19*cos(3*i) + 40)*cos(2*i),
            (19*cos(3*i) + 40)*sin(2*i),
             19*sin(3*i) ] ];
 
-sweep(knot, L_points, loop = true);
+color("red") sweep(knot, L_points, loop = true);
 
 p = transform_points([[0,0,0], [20,0,5], [10,30,4], [0,0,0], [0,0,20]], scale(10));
 n = 100;
 path = bezier_path(p, n);
 
-rotate(45) sweep(path, circle_points(5, $fn = 64));
+color("blue") rotate(45) sweep(path, circle_points(5, $fn = 64));
+
+vertices = [[-170, 0, 0], [-170, 170, 0], 10, [-170, 170, 30], 20, [-50, 170, 31], 10, [-130, 100, 40]];
+rounded_path = rounded_path(vertices);
+
+show_path(rounded_path_vertices(vertices));
+
+paths = spiral_paths(rounded_path, 2, 1.5, 15, 0);
+for(i = [0 : len(paths) - 1])
+    color(["red", "green"][i])
+        sweep(paths[i],  circle_points(1.5, $fn = 64));

utils/sweep.scad

@@ -25,6 +25,12 @@
 //!
 //! The path can be open or closed. If closed sweep ensures that the start and end have the same rotation to line up.
 //! An additional twist around the path can be specified. If the path is closed this should be a multiple of 360.
+//!
+//! `rounded_path()` can be used to generate a path of lines connected by arcs, useful for wire runs, etc.
+//! The vertices specify where the the path would be without any rounding.
+//! Each vertex, apart from the first and the last, has an associated radius and the path shortcuts the vertex with an arc specified by the radius.
+//!
+//! `spiral_paths()` makes a list of new paths that spiral around a given path. It can be used to make twisted wires that follow a rounded_path, for example.
 //
 include <../utils/core/core.scad>
 
@@ -103,18 +109,19 @@ function helical_twist_per_segment(r, pitch, sides) = //! Calculate the twist ar
        ) step_angle * sin(slope);                   // angle tangent should rotate around z projected onto axis rotate_from_to() uses
 
 //
-// Generate all the surface points of the swept volume.
+// Generate all the transforms for the profile of the swept volume.
 //
-function skin_points(profile, path, loop, twist = 0) =
+function sweep_transforms(path, loop = false, twist = 0) =
     let(len = len(path),
         last = len - 1,
 
-        profile4 = [for(p = profile) [p.x, p.y, p.z, 1]],
-
         tangents = [tangent(path, loop ? last : 0, 0, 1),
                     for(i = [1 : last - 1]) tangent(path, i - 1, i, i + 1),
                     tangent(path, last - 1, last, loop ? 0 : last)],
 
+        lengths = [for(i = 0, t = 0; i < len; t = t + norm(path[min(i + 1, last)] - path[i]), i = i + 1) t],
+        length = lengths[last],
+
         rotations = [for(i = 0, rot = fs_frame(tangents);
                          i < len;
                          i = i + 1,
@@ -124,8 +131,20 @@ function skin_points(profile, path, loop, twist = 0) =
         rotation = missmatch + twist
     )
     [for(i = [0 : last])
-        let(za = rotation * i / last)
-            each profile4 * orientate(path[i], rotations[i] * rot3_z(za))
+        let(za = rotation * lengths[i] / length)
+            orientate(path[i], rotations[i] * rot3_z(za))
+    ];
+
+//
+// Generate all the surface points of the swept volume.
+//
+function skin_points(profile, path, loop, twist = 0) =
+    let(profile4 = [for(p = profile) [p.x, p.y, p.z, 1]],
+
+        transforms = sweep_transforms(path, loop, twist)
+    )
+    [for(t = transforms)
+        each profile4 * t
     ];
 
 function cap(facets, segment = 0, end) = //! Create the mesh for an end cap
@@ -179,3 +198,65 @@ function before(path1, path2) =  //! Translate `path1` so its end meets the star
 function after(path1, path2) =  //! Translate `path2` so its start meets the end of `path1` and then concatenate
     let(end1 = len(path1) - 1, end2 = len(path2) - 1, offset = path1[end1] - path2[0])
         concat(path1, [for(i = [1 : end2]) path2[i] + offset]);
+
+function rounded_path(path) = //! Convert a rounded_path, consisting of a start coordinate, vertex / radius pairs and then an end coordinate, to a path of points for sweep.
+    let(len = len(path)) assert(len > 3 && len % 2 == 0) [
+        path[0],                                        // First point has no radius
+        for(i = [1 : 2 : len - 3]) let(                 // Step through the vertices with radii, i.e. not the first or last
+            prev = max(i - 2, 0),                       // Index of previous point, might be the first point, which is a special case
+            p0 = path[prev],                            // Point before the vertex
+            p1 = path[i],                               // Vertex
+            r = path[i + 1],                            // Radius of shortcut curve
+            p2 = path[i + 2],                           // Point after the vertex
+            v1 = assert(Len(p0) == 3, str("expected path[", prev,  "] to be a vertex coordinate, got ", p0))
+                 assert(Len(p1) == 3, str("expected path[", i,     "] to be a vertex coordinate, got ", p1))
+                 assert(Len(p2) == 3, str("expected path[", i + 2, "] to be a vertex coordinate, got ", p2))
+                 assert(is_num(r),    str("expected path[", i + 1, "] to be a radius, got ", r))
+            p0 - p1,                                    // Calculate vectors between vertices
+            v2 = p2 - p1,
+            a = angle_between(v1, -v2),                 // Angle turned through
+            arc_start = p1 + unit(v1) * r * tan(a / 2), // Calc the start position
+            z_axis = unit(cross(v1, v2)),               // z_axis is perpendicular to both vectors
+            centre = arc_start + unit(cross(z_axis, v1)) * r, // Arc center is a radius away, and perpendicular to v1 and the z_axis.
+            x_axis = arc_start - centre,                // Make the x_axis along the radius to the start point, includes radius a scale factor
+            y_axis = cross(x_axis, z_axis),             // y_axis perpendicular to the other two
+            sides = r2sides(ceil(r2sides(r) * a / 360)) // Sides needed to make the arc
+        )
+        for(j = [0 : sides], t = a * j / sides)         // For each vertex in the arc
+            cos(t) * x_axis + sin(t) * y_axis + centre, // Circular arc in the tiled xy plane.
+        path[len - 1],                                  // Last point has no radius
+    ];
+
+function segmented_path(path, min_segment) = [  //! Add points to a path to enforce a minimum segment length
+    for(i = [0 : len(path) - 2])
+            let(delta =
+                    assert(path[i] != path[i + 1], str("Coincident points at path[", i, "] = ", path[i]))
+                    path[i+1] - path[i],
+                segs = ceil(norm(delta) / min_segment)
+            )
+            for(j = [0 : segs - 1])
+                path[i] + delta * j / segs, // Linear interpolation
+            path[len(path) - 1]
+];
+
+function spiral_paths(path, n, r, twists, start_angle) = let( //! Create a new paths which sprial around the given path. Use for making twisted cables
+        segment = path_length(path) / twists / r2sides(2 * r),
+        transforms = sweep_transforms(segmented_path(path, segment), twist = 360 * twists),
+        initial = [r, 0, 0, 1] * rotate(start_angle)
+    ) [for(i = [0 : n - 1]) let(initial = [r, 0, 0, 1] * rotate(start_angle + i * 360 / n)) [for(t = transforms) initial * t]];
+
+function rounded_path_vertices(path) = [path[0], for(i = [1 : 2 : len(path) - 1]) path[i]]; //! Show the unrounded version of a rounded_path for debug
+
+module show_path(path) //! Show a path using a chain of hulls for debugging, duplicate points are highlighted.
+    for(i = [0 : len(path) - 2]) {
+        hull($fn = 16) {
+            translate(path[i])
+                sphere(0.1);
+
+            translate(path[i + 1])
+                sphere(0.1);
+        }
+        if(path[i] == path[i + 1])
+            translate(path[i])
+                color("red") sphere(1);
+    }