From abab3a7b27855f18f07e44f7fd532ff2fa167a3c Mon Sep 17 00:00:00 2001
From: djerun <djerun@hamburg.ccc.de>
Date: Sun, 15 Jun 2025 14:58:41 +0200
Subject: [PATCH] [WIP] primitives library

---
 primitives.scad | 113 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 113 insertions(+)
 create mode 100644 primitives.scad

diff --git a/primitives.scad b/primitives.scad
new file mode 100644
index 0000000..b73deca
--- /dev/null
+++ b/primitives.scad
@@ -0,0 +1,113 @@
+include <globals.scad>
+
+id = function (x) x;
+
+lerp = function (v, old_min, old_max, new_min, new_max) (v-old_min)/(old_max-old_min)*(new_max-new_min)+new_min;
+
+scalc = function (f, v, min, max) lerp(f(lerp(v, min, max, 0, 1)), 0, 1, min, max);
+
+normalize = function (vector) vector / norm(vector);
+
+mat_T = function (mat) [
+  for (x_y=[0:len(mat[0])-1]) [
+    for (y_x=[0:len(mat)-1]) mat[y_x][x_y]
+  ]
+];
+
+bezier_matrix = [[1, -3,  3, -1],
+                 [0,  3, -6,  3],
+                 [0,  0,  3, -3],
+                 [0,  0,  0,  1]];
+
+spline = function (control_points, spline_matrix, t) mat_T(control_points) * spline_matrix * [1, t, t*t, t*t*t];
+
+bezier_spline = function (control_points, t) spline(control_points, bezier_matrix, t);
+
+bezier_curve_vertices = function (control_points, $fn=$fn) [
+  for (t=[0:1/($fn-1):1]) bezier_spline(control_points, t)
+];
+
+module bezier_curve_debug(control_points, $fn=$fn) {
+  #color("red") for (c = control_points) translate(c) sphere(d=4, $fn=32);
+  color("yellow") for (v = bezier_curve_vertices(control_points, $fn)) translate(v) sphere(d=.5, $fn=16);
+  color("green") translate(bezier_spline(control_points, 0.5)) sphere(d=1, $fn=24);
+}
+
+
+
+rendered_curve_segment_vertices = function (p, v, n, width, height, chamfer) [];
+
+module render_curve(curve_vertices, width, height, chamfer) {
+  start = let(v=curve_vertices[0], n=curve_vertices[1]) let(p=v-n)
+    rendered_curve_segment_vertices(p, v, n, width, height, chamfer);
+  middle = [ for (i=[1:len(curve_vertices)-2]) let(
+    p = curve_vertives[i-1],
+    v = curve_vertices[i],
+    n = curve_vertives[i+1]
+    ) rendered_curve_segment_vertices(p, v, n, width, height, chamfer)
+  ];
+  end = let(i=len(curve_vertices)) let(v=curve_vertices[i], p=curve_vertices[i-1]) let(n=v-p)
+    rendered_curve_segment_vertices(p, v, n, width, height, chamfer);
+
+  // TODO
+}
+
+arc_vertex = function (a, r, t, translate=[0,0,0], remap=id) remap([
+    translate.x+cos(a*t)*r,
+    translate.y+sin(a*t)*r,
+    translate.z
+]);
+
+arc_vertices = function (a, r, t, x=0, y=0, z=0, remap=id, arc_vertex=arc_vertex) [
+  for (i=[0:1/(t-1):1]) arc_vertex(a, r, i, translate=[x,y,z], remap=remap)
+];
+
+module arc(part, radius, thickness, height, $fn=$fn, outer_remap=id, inner_remap=id, arc_vertices=arc_vertices) {
+  a = 360 * part;
+  r = radius+thickness/2;
+  w = thickness;
+  h = height;
+  t = $fn;
+
+  vertices_lower_outer = arc_vertices(a, r  , t, z=-h/2, remap=outer_remap);
+  vertices_lower_inner = arc_vertices(a, r-w, t, z=-h/2, remap=inner_remap);
+  vertices_upper_outer = arc_vertices(a, r  , t, z= h/2, remap=outer_remap);
+  vertices_upper_inner = arc_vertices(a, r-w, t, z= h/2, remap=inner_remap);
+  vertices = concat(
+    vertices_lower_outer,
+    vertices_lower_inner,
+    vertices_upper_outer,
+    vertices_upper_inner
+  );
+
+  faces_end1 = [ 0,  t, 3*t, 2*t];
+  faces_end2 = [ 2*t-1,  t-1, 3*t-1, 4*t-1];
+  faces_lower = concat(
+    [ for (i=[t-1:-1:0]) i ],
+    [ for (i=[t:1:2*t-1]) i ]
+  );
+  faces_upper = concat(
+    [ for (i=[2*t:1:3*t-1]) i ],
+    [ for (i=[4*t-1:-1:3*t]) i ]
+  );
+  faces_outer = [ for (i=[0:1:t-2]) [i, 2*t+i, 2*t+i+1, i+1] ];
+  faces_inner = [ for (i=[0:1:t-2]) [t+i, t+i+1, 3*t+i+1, 3*t+i] ];
+
+  faces = concat(
+    [faces_end1],
+    [faces_end2],
+    [faces_lower],
+    [faces_upper],
+    faces_outer,
+    faces_inner
+  );
+
+  rotate(a/2) polyhedron(vertices, faces);
+}
+
+module partial_ring(part, radius, thickness, height) {
+  rotate(180-180*part, [0, 0, 1])
+    rotate_extrude(angle=360*part)
+      translate([radius, 0])
+        square([thickness, height], center=true);
+}