Bresenham's line drawing algorithm added

mgechev · mgechev · commit 3bbb02f72d20 · 2013-09-07T21:28:50.000+03:00
diff --git a/src/graphics/bresenham-line-drawing.js b/src/graphics/bresenham-line-drawing.js
@@ -0,0 +1,38 @@
+/**
+ * Bresenham's line drawing algorithm.
+ * It has complexity O(n)
+ * @param  {number} x1 The first coordinate of the beginning of the line
+ * @param  {number} y1 The second coordinate of the beginning of the line
+ * @param  {number} x2 The first coordinate of the end of the line
+ * @param  {number} y2 The second coordinate of the end of the line
+ */
+function drawLine(x1, y1, x2, y2) {
+  var dx = Math.abs(x2 - x1),
+    dy = Math.abs(y2 - y1),
+    cx = (x1 < x2) ? 1 : -1,
+    cy = (y1 < y2) ? 1 : -1,
+    error = dx - dy,
+    doubledError;
+  
+  while (x1 !== x2 || y1 !== y2) {
+    drawPoint(x1, y1);
+    doubledError = error + error;
+    if (doubledError > -dy) {
+      error -= dy;
+      x1 += cx;
+    }
+    if (doubledError < dx) {
+      error += dx;
+      y1 += cy;
+    }
+  }
+}
+
+/**
+ * Draws (prints) the given coordinates
+ * @param  {number} x The first coordinate of the point
+ * @param  {number} y The second coordinate of the point
+ */
+function drawPoint(x, y) {
+  console.log(x, y);
+}
