1 files changed, 67 insertions, 0 deletions
diff --git a/js/draw.js b/js/draw.js
index cedfea2..eb58a27 100644
--- a/js/draw.js
+++ b/js/draw.js
@@ -27,6 +27,72 @@ var draw = (function(){
     last_point[1] = point[1]
   }
   
+  function move_toroidal (e, lex, point) {
+    var w = canvas.w, h = canvas.h
+    var src_x_quantile = quantile( last_point[0], w )
+    var src_y_quantile = quantile( last_point[1], h )
+    var dst_x_quantile = quantile( point[0], w )
+    var dst_y_quantile = quantile( point[1], h )
+    var src_x_mod = mod( last_point[0], w )
+    var src_y_mod = mod( last_point[1], h )
+    var dst_x_mod = mod( point[0], w )
+    var dst_y_mod = mod( point[1], h )
+    // if we've moved across the edge of the board, draw two lines
+    if (src_x_quantile != dst_x_quantile || src_y_quantile != dst_y_quantile) {
+      var xa, ya
+      if (src_x_quantile < dst_x_quantile) {
+        xa = [
+          [src_x_mod, dst_x_mod + w],
+          [src_x_mod-w, dst_x_mod],
+        ]
+      }
+      else if (src_x_quantile == dst_x_quantile) {
+        xa = [
+          [src_x_mod, dst_x_mod],
+          [src_x_mod, dst_x_mod],
+        ]
+      }
+      else {
+        xa = [
+          [src_x_mod, dst_x_mod-w],
+          [src_x_mod+w, dst_x_mod],
+        ]
+      }
+
+      if (src_y_quantile < dst_y_quantile) {
+        ya = [
+          [src_y_mod, dst_y_mod + h],
+          [src_y_mod-h, dst_y_mod],
+        ]
+      }
+      else if (src_y_quantile == dst_y_quantile) {
+        ya = [
+          [src_y_mod, dst_y_mod],
+          [src_y_mod, dst_y_mod],
+        ]
+      }
+      else {
+        ya = [
+          [src_y_mod, dst_y_mod-h],
+          [src_y_mod+h, dst_y_mod],
+        ]
+      }
+      line(lex, [ xa[0][0], ya[0][0] ], [ xa[0][1], ya[0][1] ], erasing)
+      line(lex, [ xa[1][0], ya[1][0] ], [ xa[1][1], ya[1][1] ], erasing)
+    }
+    else {
+      var last_point_mod = [], point_mod = []
+      last_point_mod[0] = mod( last_point[0], w )
+      last_point_mod[1] = mod( last_point[1], h )
+      point_mod[0] = mod( point[0], w )
+      point_mod[1] = mod( point[1], h )
+      line(lex, last_point_mod, point_mod, erasing)
+    }
+    last_point[0] = point[0]
+    last_point[1] = point[1]
+    // y = point.y
+  }
+  
   function point (lex, x, y, erasing) {
     stamp (canvas, brush, x, y, erasing)
   }
@@ -109,6 +175,7 @@ var draw = (function(){
   draw.down = down
   draw.set_last_point = set_last_point
   draw.move = move
+  draw.move_toroidal = move_toroidal
   draw.stamp = stamp
   draw.line = line
   draw.point = point