From e47a8bb40587df88859dd63b9420acca50902adb Mon Sep 17 00:00:00 2001
From: Justin Lin <justin.sdk@gmail.com>
Date: Fri, 16 Apr 2021 18:29:37 +0800
Subject: [PATCH] add tri_delaunay2voronoi

---
 .../_impl/_tri_delaunay2voronoi_impl.scad     | 23 +++++++++
 .../demo/tri_delaunay2voronoi_demo.scad       | 22 +++++++++
 src/experimental/tri_delaunay2voronoi.scad    | 47 +++++++++++++++++++
 3 files changed, 92 insertions(+)
 create mode 100644 src/experimental/_impl/_tri_delaunay2voronoi_impl.scad
 create mode 100644 src/experimental/demo/tri_delaunay2voronoi_demo.scad
 create mode 100644 src/experimental/tri_delaunay2voronoi.scad

diff --git a/src/experimental/_impl/_tri_delaunay2voronoi_impl.scad b/src/experimental/_impl/_tri_delaunay2voronoi_impl.scad
new file mode 100644
index 00000000..799ccf88
--- /dev/null
+++ b/src/experimental/_impl/_tri_delaunay2voronoi_impl.scad
@@ -0,0 +1,23 @@
+use <experimental/tri_delaunay.scad>;
+use <util/map/hashmap_get.scad>;
+use <util/find_index.scad>;
+
+function delaunay_coords(d) = d[0];
+function delaunay_triangles(d) = d[1];
+function delaunay_circles(d) = d[2];
+	
+function indicesOfCell(iTris, triIndices) = 
+    let(
+	    vi = iTris[0][0],
+		indices = [],
+		leng = len(iTris)
+	)
+	_indicesOfCell(iTris, triIndices, leng, indices, vi);
+
+function _indicesOfCell(iTris, triIndices, leng, indices, vi, i = 0) =
+    i == leng ? indices :
+	let(
+	    t = iTris[find_index(iTris, function(t) t[0] == vi)],
+		nIndices = concat(indices, hashmap_get(triIndices, t))
+	)
+	_indicesOfCell(iTris, triIndices, leng, nIndices, t[1], i + 1);
diff --git a/src/experimental/demo/tri_delaunay2voronoi_demo.scad b/src/experimental/demo/tri_delaunay2voronoi_demo.scad
new file mode 100644
index 00000000..ad0e0e6e
--- /dev/null
+++ b/src/experimental/demo/tri_delaunay2voronoi_demo.scad
@@ -0,0 +1,22 @@
+use <experimental/tri_delaunay.scad>;
+use <experimental/tri_delaunay2voronoi.scad>;
+use <hull_polyline2d.scad>;
+
+points = [for(i = [0:20]) rands(-100, 100, 2)]; 
+
+color("black")
+for(p = points) {
+    translate(p)
+	circle(2);
+}
+
+%draw(tri_delaunay(points));
+
+d = tri_delaunay(points, ret = "DELAUNAY");
+#draw(tri_delaunay2voronoi(d));
+
+module draw(pointsOfTriangles) {
+	for(t = pointsOfTriangles) {
+	    hull_polyline2d(concat(t, [t[0]]));
+	}	
+}
\ No newline at end of file
diff --git a/src/experimental/tri_delaunay2voronoi.scad b/src/experimental/tri_delaunay2voronoi.scad
new file mode 100644
index 00000000..8296a741
--- /dev/null
+++ b/src/experimental/tri_delaunay2voronoi.scad
@@ -0,0 +1,47 @@
+use <experimental/_impl/_tri_delaunay2voronoi_impl.scad>;
+use <util/map/hashmap.scad>;
+use <util/map/hashmap_keys.scad>;
+use <util/map/hashmap_get.scad>;
+
+function tri_delaunay2voronoi(d) = 
+    let(
+	    coords = delaunay_coords(d),
+		coords_leng = len(coords),
+		circles = delaunay_circles(d),
+		tris = hashmap_keys(delaunay_triangles(d)),
+        // circumcircle centers
+        vertices = [for(t = tris) hashmap_get(circles, t)[0]],
+		i_rts = [
+			for(i = [0:len(tris) - 1])
+			let(
+				a = tris[i][0],
+				b = tris[i][1],
+				c = tris[i][2],
+			    rt1 = [b, c, a],
+			    rt2 = [c, a, b],
+			    rt3 = [a, b, c]
+			) 
+			each [[a, rt1], [b, rt2], [c, rt3]]
+		],
+		connectedTris = [
+		    for(i = [0:coords_leng - 1])
+			[for(i_rt = i_rts) if(i_rt[0] == i) i_rt[1]]
+		],
+		triIndices = hashmap([
+			for(i = [0:len(tris) - 1])
+			let(
+				a = tris[i][0],
+				b = tris[i][1],
+				c = tris[i][2],
+			    rt1 = [b, c, a],
+			    rt2 = [c, a, b],
+			    rt3 = [a, b, c]
+			) 
+			each [[rt1, i], [rt2, i], [rt3, i]]
+		]),
+		cells = [
+		    for(i = [4:coords_leng - 1])
+			indicesOfCell(connectedTris[i], triIndices)
+		]
+    )
+	[for(cell = cells) [for(i = cell) vertices[i]]];