Function zOrder

libs/mapv/mapv.js:2039–2055

(x, y, minX, minY, size)

// z-order of a point given coords and size of the data bounding box
function zOrder(x, y, minX, minY, size) {
    // coords are transformed into non-negative 15-bit integer range
    x = 32767 * (x - minX) / size;
    y = 32767 * (y - minY) / size;

    x = (x | x << 8) & 0x00FF00FF;
    x = (x | x << 4) & 0x0F0F0F0F;
    x = (x | x << 2) & 0x33333333;
    x = (x | x << 1) & 0x55555555;

    y = (y | y << 8) & 0x00FF00FF;
    y = (y | y << 4) & 0x0F0F0F0F;
    y = (y | y << 2) & 0x33333333;
    y = (y | y << 1) & 0x55555555;

    return x | y << 1;
}

// find the leftmost node of a polygon ring
function getLeftmost(start) {