code: function(inPositions) {
  			var p = inPositions;
  			// yay math!, rad -> deg
  			var a = Math.asin(p.y / p.h) * (180 / Math.PI);
  			// fix for range limits of asin (-90 to 90)
  			// Quadrants II and III
  			if (p.x < 0) {
  				a = 180 - a;
  			}
  			// Quadrant IV
  			if (p.x > 0 && p.y < 0) {
  				a += 360;
  			}
  			return a;
  		}
docs: find rotation angle