adding rotation sets

1 files changed, 75 insertions, 0 deletions

diff --git a/orientation.py b/orientation.py
new file mode 100644
index 0000000..d31579c
--- /dev/null
+++ b/orientation.py
@@ -0,0 +1,75 @@
+# There are a limited number of valid orientation combinations available,
+# assuming each card has two neighboring patterns of the same gender, e.g.,
+# north and east are the same gender, wst and south are the same gender in the
+# initial position
+#
+# Since the gender of a neighboring edge has to be opposite, the following
+# constraints apply:
+#
+ORIENTATION_CONSTRAINTS = [(-1,-1),(0,-1),(1,-1), \
+                           (-1,0), (3,1), (4,2), \
+                           (-1,3), (6,4), (7,5)]
+# where the pairs are (left dependency, top dependency)
+# and -1 indicates an edge, i.e., no dpendency
+#
+# Thus there are 4x2x2x2x1x1x2x1x1 = 64 possible orientation sets.
+
+# unconstrained positions
+ROTS = (0,90,180,270)
+
+# constraint tables
+LEFT = {0:(0,270),90:(90,180),180:(90,180),270:(0,270)}
+TOP = {0:(0,90),90:(0,90),180:(180,270),270:(180,270)}
+TOP_LEFT = [{0:0,90:90,180:90,270:0}, \
+                 {0:0,90:90,180:90,270:0}, \
+                 {0:270,90:180,180:180,270:270}, \
+                 {0:270,90:180,180:180,270:270}]
+
+def get_rotation_sets():
+
+    # Create a list of rotation sets (assuming CCW rotation)
+    rot_sets = []
+    for i in range(64):
+        rot_sets.append([])
+    
+    # first tile can be any rotation (4 groups of 16)
+    for i in range(4):
+        for j in range(16):
+            rot_sets[i*16+j].append(ROTS[i])
+
+    # second tile is constrained to the left only (4 groups of 8x2)
+    for i in range(4):
+        for j in range(8):
+            rot_sets[i*16+j].append(LEFT[rot_sets[i*16+j][0]][0])
+            rot_sets[i*16+j+8].append(LEFT[rot_sets[i*16+j+8][0]][1])
+
+    # third tile is constrained to the left only (8 groups of 4x2)
+    for i in range(8):
+        for j in range(4):
+            rot_sets[i*8+j].append(LEFT[rot_sets[i*8+j][1]][0])
+            rot_sets[i*8+j+4].append(LEFT[rot_sets[i*8+j+4][1]][1])
+
+    # fourth tile is constrained to the top only (16 groups of 2x2
+    for i in range(16):
+        for j in range(2):
+            rot_sets[i*4+j].append(TOP[rot_sets[i*4+j][1]][0])
+            rot_sets[i*4+j+2].append(TOP[rot_sets[i*4+j+2][1]][1])
+
+    # fifth tile is constrained by top and left
+    # sixth tile is constrained by top and left
+    for i in range(64):
+        rot_sets[i].append(TOP_LEFT[ROTS.index(rot_sets[i][1])][rot_sets[i][3]])
+        rot_sets[i].append(TOP_LEFT[ROTS.index(rot_sets[i][2])][rot_sets[i][4]])
+
+    # seventh tile is constrained to the top only (32 groups of 1x2)
+    for i in range(32):
+        rot_sets[i*2].append(TOP[rot_sets[i*2][4]][0])
+        rot_sets[i*2+1].append(TOP[rot_sets[i*2+1][4]][1])
+
+    # eigth tile is constrained by top and left
+    # ninth tile is constrained by top and left
+    for i in range(64):
+        rot_sets[i].append(TOP_LEFT[ROTS.index(rot_sets[i][4])][rot_sets[i][6]])
+        rot_sets[i].append(TOP_LEFT[ROTS.index(rot_sets[i][5])][rot_sets[i][7]])
+
+    return rot_sets