function decodePolygon(coordinate, encodeOffsets, encodeScale) {
	        var result = [];
	        var prevX = encodeOffsets[0];
	        var prevY = encodeOffsets[1];

	        for (var i = 0; i < coordinate.length; i += 2) {
	            var x = coordinate.charCodeAt(i) - 64;
	            var y = coordinate.charCodeAt(i + 1) - 64;
	            // ZigZag decoding
	            x = (x >> 1) ^ (-(x & 1));
	            y = (y >> 1) ^ (-(y & 1));
	            // Delta deocding
	            x += prevX;
	            y += prevY;

	            prevX = x;
	            prevY = y;
	            // Dequantize
	            result.push([x / encodeScale, y / encodeScale]);
	        }

	        return result;
	    }
Simple view coordinate system
Mapping given x, y to transformd view x, y