add tri_delaunay

src/experimental/_impl/_tri_delaunay_impl.scad

@@ -0,0 +1,48 @@
+use <experimental/tri_circumcircle.scad>;
+
+// [max, min, min, max]      
+function _tri_delaunay_boundIndices(points, leng, indices, i = 0) =
+    let(
+        bounds = i < leng - 1 ? _tri_delaunay_boundIndices(points, leng, indices, i + 1)
+                              : [undef, undef, undef, undef],
+        p0 = points[indices[0]],
+        p1 = points[indices[1]],
+        p2 = points[i],
+        c_circle = tri_circumcircle([p0, p1, p2]),
+        r = c_circle[1],
+        cside = c_circle == [] ? undef : cross(p1 - p0, c_circle[0] - p1),
+        pside = cross(p1 - p0, p2 - p1),
+        pdot = (p2 - p0) * (p2 - p1)
+    )
+    pdot < 0 && 0 == pside  ? [-1, 1, 1, -1] :
+    c_circle == [] ? bounds :
+    pside > 0 && cside > 0  ? [bounds[0], bounds[1], bounds[2], bounds[3] ? min(bounds[3], r) : r]  :
+    pside > 0 && cside <= 0 ? [bounds[0], bounds[1], bounds[2] ? max(bounds[2], r) : r, bounds[3]] :
+    pside <= 0 && cside > 0 ? [bounds[0], bounds[1] ? max(bounds[1],r) : r, bounds[2], bounds[3]] :
+                              [bounds[0] ? min(bounds[0], r) : r, bounds[1], bounds[2], bounds[3]]; // is_undef(cside) also returns this
+
+function _tri_delaunay_try_triangle(points, indices_boundIndices, i) = 
+   let(
+      indices = indices_boundIndices[0],
+      bounds = indices_boundIndices[1],
+      p0 = points[indices[0]],
+      p1 = points[indices[1]],
+      p2 = points[i],
+      c_circle = tri_circumcircle([p0, p1, p2]),
+      r = c_circle[1],
+      cside = c_circle == [] ? undef : cross(p1 - p0, c_circle[0] - p1)
+   )
+   c_circle == [] ? undef : 
+   (cside > 1  && (!bounds[2] && (!bounds[1] || r>=bounds[1]) && (!bounds[3] || r<=bounds[3]))) ||
+   (cside <= 1 && (!bounds[1] && (!bounds[2] || r>=bounds[2]) && (!bounds[0] || r<=bounds[0]))) ? concat(indices, [i]) :
+   undef;
+   
+function _tri_delaunay_triangleIndices(points, leng, indices_boundIndices, triangles, i = 0) =
+   let(
+      indices = indices_boundIndices[0],
+      newtriangle = _tri_delaunay_try_triangle(points, indices_boundIndices, i),
+      newtriangles = newtriangle ? concat(triangles, [newtriangle]) : triangles
+   )
+   i <= indices[1] ? _tri_delaunay_triangleIndices(points, leng, indices_boundIndices, [], indices[1] + 1) : 
+   i< leng - 1 ? _tri_delaunay_triangleIndices(points, leng, indices_boundIndices, newtriangles,i + 1) :
+   newtriangles;

src/experimental/tri_delaunay.scad

@@ -0,0 +1,18 @@
+use <experimental/_impl/_tri_delaunay_impl.scad>;
+use <experimental/flat.scad>;
+
+function tri_delaunay(points)=
+   let(
+      leng = len(points),
+      indices_lt = [for(i=[0:leng - 3]) for(j = [i + 1:leng - 2]) [i, j]],
+      indices_boundIndices_lt = [
+          for(indices = indices_lt) 
+              [indices, _tri_delaunay_boundIndices(points, leng, indices)]
+      ]
+   )
+   flat(
+       [
+           for(indices_boundIndices = indices_boundIndices_lt) 
+               _tri_delaunay_triangleIndices(points, leng, indices_boundIndices, [])
+       ]
+   );