add sf_bend

src/experimental/sf_bend.scad

@@ -0,0 +1,51 @@
+use <experimental/sf_solidify.scad>;
+use <experimental/tf_bend.scad>;
+
+/*
+    levels : A list of numbers (0 ~ 255).
+    radius: The radius of the arc after being bent
+    thickness: shell thickness
+    angle: The central angle of the arc..
+    invert: inverts how the gray levels are translated into height values.
+*/
+module sf_bend(levels, radius, thickness, angle, invert = false) {
+    columns = len(levels);
+    rows = len(levels[0]);
+    
+    size = [columns - 1, rows - 1];
+
+    surface1 = [
+        for(r = [0:rows - 1]) 
+        [
+            for(c = [0:columns - 1]) 
+            let(lv = invert ? 255 - levels[c][r] : levels[c][r])
+            [c, r, lv / 255 * thickness]
+        ]
+    ];
+
+    surface2 = [
+        for(r = [0:rows - 1]) 
+        [
+            for(c = [0:columns - 1]) 
+            [c, r, 0]
+        ]
+    ];
+
+    offset_z = invert ? thickness : 0;
+    sf_solidify(
+        [
+            for(row = surface1) 
+            [
+                for(p = row) 
+                tf_bend(size, p, radius + offset_z, angle)
+            ]
+        ]
+        ,
+        [
+            for(row = surface2) 
+            [
+                for(p = row) tf_bend(size, p, radius, angle)
+            ]
+        ]
+    );
+}