Create backAndForth.js

examples/backAndForth.js

@@ -0,0 +1,60 @@
+// ====  rgb goTo ====
+var arr = new Uint8ClampedArray(100*3); // ledsNum * RGB
+var currIdx2 = 0;
+var actualIdx = 0; // not currently used
+
+var goToRgb = function(idx){
+  console.log('currIdx before move: ' + currIdx2);
+  var diff = idx - currIdx2;
+  if(diff > 0){
+    console.log('increase by ' + diff);
+    for(var i=0; i < idx*3; i+=3){ arr[i] = 255; }
+    currIdx2 += diff;
+    actualIdx = currIdx2*3;
+  }
+  else if (diff < 0){
+    console.log('decrease by ' + diff);
+    var lastCurIdx = currIdx2;
+    currIdx2 += diff;
+    ////for(var i=currIdx2; i < lastCurIdx*3; i+=3){ arr[i] = 0; }
+    //for(var i=lastCurIdx*3; i >currIdx2; i-=3){ arr[i] = 0; } // doesn't work 4 all
+    //for(var i=currIdx2-1; i < idx*3; i+=3){ arr[i] = 3; }
+    for(var i=currIdx2*3; i < lastCurIdx*3; i++){
+      console.log('decreasing ..');
+      arr[i] = 0;
+    }
+  }
+  else if(diff == 0) { console.log('no move'); }
+  console.log('currIdx is now ' + currIdx2);
+  console.log('arr is now ' + arr.toString() );
+}
+
+// test out
+var max = 100;
+var curr = 0;
+/* increasing to full only
+setInterval(function(){
+  if( curr < max) curr++;
+  else curr = 0;
+  goToRgb(curr);
+require("neopixel").write('F1', arr);
+}, 50);
+*/
+/* decreasing to empty only
+setInterval(function(){
+  if( curr > 0) curr--;
+  else curr = max;
+  goToRgb(curr);
+require("neopixel").write('F1', arr);
+}, 50);
+*/
+// back & forth, starting with forth
+var dir = 0; // 0 == decreasing, 1 == increasing
+setInterval(function(){
+  if( dir == 1 && curr < max) curr++;
+  else if( dir == 0 && curr > 0) curr--;
+  else dir = !dir;
+
+  goToRgb(curr);
+  require("neopixel").write('F1', arr);
+}, 50);