fix some bugs and add OBBs.

Fix some bugs and add a layout for the word cloud algorithm.

common/random.js

@@ -20,4 +20,19 @@ export function easyRandom(s) {
       seed = (seed * 16807) % 2147483647
       return (seed - 1) / 2147483647
     }
+}
+
+export function normalRandomFactory(seed, m_, s_) {
+    const mu = m_
+    const sigma = s_
+    const pi2 = 2 * Math.PI
+    const random = random_seed(seed)
+    return function( ) {
+        let u1 = 1 - random()
+        let u2 = random()
+        const mag = sigma * Math.sqrt(-2 * Math.log(u1))
+        const z0 = mag * Math.cos(pi2 * u2) + mu
+        const z1 = mag * Math.sin(pi2 * u2) + mu
+        return z0
+    }
 }

infovis/text/wordcloud.html

@@ -38,6 +38,13 @@ <h3>Perception</h3>
                 </li>
                 <li>exploration: tag clouds provide suboptimal support when searching for specific tags</li>
             </ul>
+            <h3>Algorithm</h3>
+            <p>
+                The word cloud layout algorithm is straightforward. For each word, an outgoing spiraling path centered at the center 
+                of the drawing area is generated. Words are moved stepwise along the path. At each step, if the word is place in the 
+                canvas if there are no collision with other words. The computation of collisions uses OBBs and the 
+                Separating Axis Theorem.
+            </p>
             <hr>
             <div class="canvas">
                 <div id="word-cloud" class="grid-container-1-column"></div>