From 018b2e8be2425f8a40e7612d878b96e3a2f7e413 Mon Sep 17 00:00:00 2001
From: Justin Lin <caterpillar@openhome.cc>
Date: Tue, 18 Feb 2020 11:13:11 +0800
Subject: [PATCH] add surface_grapher

---
 src/experimental/surface_grapher.scad | 159 ++++++++++++++++++++++++++
 1 file changed, 159 insertions(+)
 create mode 100644 src/experimental/surface_grapher.scad

diff --git a/src/experimental/surface_grapher.scad b/src/experimental/surface_grapher.scad
new file mode 100644
index 00000000..864eb30d
--- /dev/null
+++ b/src/experimental/surface_grapher.scad
@@ -0,0 +1,159 @@
+/**
+* surface_grapher.scad
+*
+* @copyright Justin Lin, 2020
+* @license https://opensource.org/licenses/lgpl-3.0.html
+*
+* @see https://openhome.cc/eGossip/OpenSCAD/lib2x-surface_grapher.html
+*
+**/ 
+
+use <util/reverse.scad>;
+use <experimental/flat.scad>;
+
+module surface_grapher(surface1, surface2, slicing = "SLASH") {
+    rows = len(surface1);
+    columns = len(surface1[0]);
+
+    yi_range = [0:rows - 2];
+    xi_range =  [0:columns - 2];
+
+    module faces() {
+        function xy_to_index(x, y, columns) = y * columns + x; 
+
+        flatted_sf1 = flat(surface1);
+        flatted_sf2 = flat(surface2);
+        
+        leng_pts = len(flatted_sf1);
+                
+        sf1_tri_faces1 = slicing == "SLASH" ? [
+            for(yi = yi_range) 
+                for(xi = xi_range)
+                    [
+                        xy_to_index(xi, yi, columns),
+                        xy_to_index(xi + 1, yi + 1, columns),
+                        xy_to_index(xi + 1, yi, columns)
+                    ]    
+        ] : [
+            for(yi = yi_range)
+                for(xi = xi_range)
+                    [
+                        xy_to_index(xi, yi, columns),
+                        xy_to_index(xi, yi + 1, columns),
+                        xy_to_index(xi + 1, yi, columns)
+                    ]    
+        ];
+
+        sf1_tri_faces2 = slicing == "SLASH" ? [
+            for(yi = yi_range) 
+                for(xi = xi_range)
+                    [
+                        xy_to_index(xi, yi, columns),
+                        xy_to_index(xi, yi + 1, columns),
+                        xy_to_index(xi + 1, yi + 1, columns)
+                    ]    
+        ] : [
+            for(yi = yi_range) 
+                for(xi = xi_range)
+                    [
+                        xy_to_index(xi, yi + 1, columns),
+                        xy_to_index(xi + 1, yi + 1, columns),
+                        xy_to_index(xi + 1, yi, columns)
+                    ]    
+        ];        
+
+        offset_v = [leng_pts, leng_pts, leng_pts];
+        sf2_tri_faces1 = [
+            for(face = sf1_tri_faces1)
+                reverse(face) + offset_v
+        ];
+
+        sf2_tri_faces2 = [
+            for(face = sf1_tri_faces2)
+                reverse(face) + offset_v
+        ];
+        
+        side_faces1 = [
+            for(xi = xi_range)
+                let(
+                    idx1 = xy_to_index(xi, 0, columns),
+                    idx2 = xy_to_index(xi + 1, 0, columns)
+                )
+                [
+                    idx1,
+                    idx2,
+                    idx2 + leng_pts,
+                    idx1 + leng_pts
+                ]
+        ];
+
+        side_faces2 = [
+            for(yi = yi_range)
+                let(
+                    xi = columns - 1,
+                    idx1 = xy_to_index(xi, yi, columns),
+                    idx2 = xy_to_index(xi, yi + 1, columns)
+                )
+                [
+                    idx1,
+                    idx2,
+                    idx2 + leng_pts,
+                    idx1 + leng_pts
+                ]
+        ];                  
+      
+        side_faces3 = [
+            for(xi = xi_range)
+                let(
+                    yi = rows - 1,
+                    idx1 = xy_to_index(xi, yi, columns), 
+                    idx2 = xy_to_index(xi + 1, yi, columns)
+                )
+                [
+                    idx2,
+                    idx1,
+                    idx1 + leng_pts,
+                    idx2 + leng_pts
+                ]
+        ];
+        
+        side_faces4 = [
+            for(yi = yi_range)
+                let(
+                    idx1 = xy_to_index(0, yi, columns),
+                    idx2 = xy_to_index(0, yi + 1, columns)
+                )
+                [
+                    idx2,
+                    idx1,
+                    idx1 + leng_pts,
+                    idx2 + leng_pts
+                ]
+        ];                  
+        
+        pts = concat(flatted_sf1, flatted_sf2);
+        face_idxs = concat(
+                sf1_tri_faces1, sf1_tri_faces2,
+                sf2_tri_faces1, sf2_tri_faces2, 
+                side_faces1, 
+                side_faces2, 
+                side_faces3, 
+                side_faces4
+            );
+
+        polyhedron(
+            points = pts, 
+            faces = face_idxs
+        );
+
+        // hook for testing
+        test_surface_grapher_faces(pts, face_idxs);
+    }
+
+    faces();
+}
+
+// override it to test
+module test_surface_grapher_faces(surface1, faces) {
+
+}
\ No newline at end of file