New grid type: compass dodecagonal

A grid based on dodecagons with square symmetry. In between dodecagons
there are 4 triangles around 1 square, which resembles a compass rose.
https://en.wikipedia.org/wiki/3-4-3-12_tiling

1 files changed, 97 insertions, 1 deletions

diff --git a/grid.c b/grid.c
index 5ea3743..7d98ab7 100644
--- a/grid.c
+++ b/grid.c
@@ -2747,7 +2747,7 @@ static grid *grid_new_greatgreatdodecagonal(int width, int height, const char *d
                 d = grid_get_dot(g, points, px + (2*a + 2*b), py - 2*a); grid_face_set_dot(g, d, 5);
             }
 
-            /* hexagon on bottom right  of dodecagon */
+            /* hexagon on bottom right of dodecagon */
             if ((y < height - 1) && (x < width - 1 || !(y % 2))) {
                 grid_face_add_new(g, 6);
                 d = grid_get_dot(g, points, px + (a + 2*b), py + (2*a + b)); grid_face_set_dot(g, d, 0);
@@ -2839,6 +2839,102 @@ static grid *grid_new_greatgreatdodecagonal(int width, int height, const char *d
     return g;
 }
 
+static void grid_size_compassdodecagonal(int width, int height,
+                                         int *tilesize, int *xextent, int *yextent)
+{
+    int a = DODEC_A;
+    int b = DODEC_B;
+
+    *tilesize = DODEC_TILESIZE;
+    *xextent = (4*a + 2*b) * width;
+    *yextent = (4*a + 2*b) * height;
+}
+
+static grid *grid_new_compassdodecagonal(int width, int height, const char *desc)
+{
+    int x, y;
+    /* Vector for side of triangle - ratio is close to sqrt(3) */
+    int a = DODEC_A;
+    int b = DODEC_B;
+
+    /* Upper bounds - don't have to be exact */
+    int max_faces = 6 * width * height;
+    int max_dots = 18 * width * height;
+
+    tree234 *points;
+
+    grid *g = grid_empty();
+    g->tilesize = DODEC_TILESIZE;
+    g->faces = snewn(max_faces, grid_face);
+    g->dots = snewn(max_dots, grid_dot);
+
+    points = newtree234(grid_point_cmp_fn);
+
+    for (y = 0; y < height; y++) {
+        for (x = 0; x < width; x++) {
+            grid_dot *d;
+            /* centre of dodecagon */
+            int px = (4*a + 2*b) * x;
+            int py = (4*a + 2*b) * y;
+
+            /* dodecagon */
+            grid_face_add_new(g, 12);
+            d = grid_get_dot(g, points, px + (  a    ), py - (2*a + b)); grid_face_set_dot(g, d, 0);
+            d = grid_get_dot(g, points, px + (  a + b), py - (  a + b)); grid_face_set_dot(g, d, 1);
+            d = grid_get_dot(g, points, px + (2*a + b), py - (  a    )); grid_face_set_dot(g, d, 2);
+            d = grid_get_dot(g, points, px + (2*a + b), py + (  a    )); grid_face_set_dot(g, d, 3);
+            d = grid_get_dot(g, points, px + (  a + b), py + (  a + b)); grid_face_set_dot(g, d, 4);
+            d = grid_get_dot(g, points, px + (  a    ), py + (2*a + b)); grid_face_set_dot(g, d, 5);
+            d = grid_get_dot(g, points, px - (  a    ), py + (2*a + b)); grid_face_set_dot(g, d, 6);
+            d = grid_get_dot(g, points, px - (  a + b), py + (  a + b)); grid_face_set_dot(g, d, 7);
+            d = grid_get_dot(g, points, px - (2*a + b), py + (  a    )); grid_face_set_dot(g, d, 8);
+            d = grid_get_dot(g, points, px - (2*a + b), py - (  a    )); grid_face_set_dot(g, d, 9);
+            d = grid_get_dot(g, points, px - (  a + b), py - (  a + b)); grid_face_set_dot(g, d, 10);
+            d = grid_get_dot(g, points, px - (  a    ), py - (2*a + b)); grid_face_set_dot(g, d, 11);
+
+            if (x < width - 1 && y < height - 1) {
+                /* north triangle */
+                grid_face_add_new(g, 3);
+                d = grid_get_dot(g, points, px + (2*a + b), py + (  a    )); grid_face_set_dot(g, d, 0);
+                d = grid_get_dot(g, points, px + (3*a + b), py + (  a + b)); grid_face_set_dot(g, d, 1);
+                d = grid_get_dot(g, points, px + (  a + b), py + (  a + b)); grid_face_set_dot(g, d, 2);
+
+                /* east triangle */
+                grid_face_add_new(g, 3);
+                d = grid_get_dot(g, points, px + (3*a + 2*b), py + (2*a + b)); grid_face_set_dot(g, d, 0);
+                d = grid_get_dot(g, points, px + (3*a +   b), py + (3*a + b)); grid_face_set_dot(g, d, 1);
+                d = grid_get_dot(g, points, px + (3*a +   b), py + (  a + b)); grid_face_set_dot(g, d, 2);
+
+                /* south triangle */
+                grid_face_add_new(g, 3);
+                d = grid_get_dot(g, points, px + (3*a + b), py + (3*a +   b)); grid_face_set_dot(g, d, 0);
+                d = grid_get_dot(g, points, px + (2*a + b), py + (3*a + 2*b)); grid_face_set_dot(g, d, 1);
+                d = grid_get_dot(g, points, px + (  a + b), py + (3*a +   b)); grid_face_set_dot(g, d, 2);
+
+                /* west triangle */
+                grid_face_add_new(g, 3);
+                d = grid_get_dot(g, points, px + (a + b), py + (  a + b)); grid_face_set_dot(g, d, 0);
+                d = grid_get_dot(g, points, px + (a + b), py + (3*a + b)); grid_face_set_dot(g, d, 1);
+                d = grid_get_dot(g, points, px + (a    ), py + (2*a + b)); grid_face_set_dot(g, d, 2);
+
+                /* square in center */
+                grid_face_add_new(g, 4);
+                d = grid_get_dot(g, points, px + (3*a + b), py + (  a + b)); grid_face_set_dot(g, d, 0);
+                d = grid_get_dot(g, points, px + (3*a + b), py + (3*a + b)); grid_face_set_dot(g, d, 1);
+                d = grid_get_dot(g, points, px + (  a + b), py + (3*a + b)); grid_face_set_dot(g, d, 2);
+                d = grid_get_dot(g, points, px + (  a + b), py + (  a + b)); grid_face_set_dot(g, d, 3);
+            }
+        }
+    }
+
+    freetree234(points);
+    assert(g->num_faces <= max_faces);
+    assert(g->num_dots <= max_dots);
+
+    grid_make_consistent(g);
+    return g;
+}
+
 typedef struct setface_ctx
 {
     int xmin, xmax, ymin, ymax;