diff --git a/src/experimental/2_edge_wang_tiles.scad b/src/experimental/2_edge_wang_tiles.scad
index 1327a9c3..3bc12fb4 100644
--- a/src/experimental/2_edge_wang_tiles.scad
+++ b/src/experimental/2_edge_wang_tiles.scad
@@ -1,4 +1,4 @@
-module 2_edge_wang_tiles(rows, columns, tile_width, seed) {
+module 2_edge_wang_tiles(rows, columns, tile_width, mask, seed) {
 	edges = is_undef(seed) ? [
 		for(y = [0:rows])
 		[
@@ -15,16 +15,26 @@ module 2_edge_wang_tiles(rows, columns, tile_width, seed) {
 		]
 	];
 
+	m = is_undef(mask) ? [
+		for(y = [0:rows - 1])
+		    [for(x = [0:columns - 1]) 1]
+	] : [
+		for(y = rows - 1; y > -1; y = y - 1)
+		    [for(x = [0:columns - 1]) mask[y][x]]
+	];
+
     half_w = tile_width / 2;
     translate([half_w, half_w])
 	for(y = [0:rows - 1]) {
 		for(x = [0:columns - 1]) {
-			i = (edges[y + 1][x][0] == 1 ? 1 : 0) +
-			(edges[y][x + 1][1] == 1 ? 2 : 0) +
-			(edges[y][x][0] == 1 ? 4 : 0) +
-			(edges[y][x][1] == 1 ? 8 : 0);
-			translate([x, y] * tile_width)
-				children(i);
+			if(m[y][x] == 1) {
+				i = (edges[y + 1][x][0] == 1 ? 1 : 0) +
+					(edges[y][x + 1][1] == 1 ? 2 : 0) +
+					(edges[y][x][0] == 1 ? 4 : 0) +
+					(edges[y][x][1] == 1 ? 8 : 0);
+				translate([x, y] * tile_width)
+					children(i);
+			}
 		}
 	}
 }
\ No newline at end of file