/*
The idea (a slight variation of a proposal by
Harold Cooper) is to extend the Manhattan
Grid in all directions, so that every point on Earth can be addressed as
"Xth Ave & Yth St".
The origin of this coordinate system is the intersection of Zero Ave (a.k.a.
Avenue A) and Zero St (a.k.a. Houston St). Avenues east of Zero Ave, just as
Streets south of Zero St, have negative numbers. Broadway, which will split not
only Manhattan but the entire globe into an eastern and a western hemisphere,
retains its orientation, but is adjusted slightly so that it originates at the
intersection of Zero & Zero. From there, Broadway, Zero Avenue and Zero Street
continue as perfectly straight equatorial lines. All three will intersect once
more, exactly halfway, in the Indian Ocean, (southwest of Australia), at the
point furthest from Manhattan.
As subsequent avenues remain exactly parallel to Zero Ave, and subsequent
streets exactly parallel to Zero St, they form smaller and smaller circles
around the globe. The northernmost and southernmost streets are small circles
in Central Asia (east of the Caspian Sea) and the southern Pacific (near Easter
Island), the westernmost and easternmost avenues small circles in the North
Pacific (west of Hawaii) and the South Atlantic (near St. Helena). These four
extreme points are the North Pole, South Pole, West Pole and East Pole of the
coordinate system.
*/
'use strict';
/*
Include the Image module.
*/
Ox.load('Image', function() {
/*
Ox.EARTH_CIRCUMFERENCE (40075016.68557849) is a built-in constant.
*/
var C = Ox.EARTH_CIRCUMFERENCE,
/*
We need a few points to determine the orientation and spacing of
avenues and streets.
*/
points = {
/*
Columbus Circle, the lower western corner of Central Park
*/
'8 & 59': {lat: 40.76807,lng: -73.98190},
/*
The upper western corner of Central Park, 51 streets up from
Columbus Circle
*/
'8 & 110': {lat: 40.80058, lng: -73.95818},
/*
The lower eastern corner of Central Park, 3 avenues east of
Columbus Circle
*/
'5 & 59': {lat: 40.76429, lng: -73.97301},
},
/*
Ox.getBearing returns the bearing, in degrees, from one lat/lng pair to
another. To make sure that avenues and streets cross at an exact right
angle, we first calculate the bearing of a line that cuts the upper
western quadrant of Columbus Circle in half, then add 45 degrees for
the direction of the avenues and subtract 45 degrees for the direction
of the streets.
*/
bearing = (
Ox.getBearing(points['8 & 59'], points['8 & 110'])
+ Ox.getBearing(points['5 & 59'], points['8 & 59'])
) / 2 + 180,
bearings = {
// fixme: Ox.mod ?
avenues: (bearing + 45) % 360,
streets: (bearing - 45) % 360
},
/*
Ox.getDistance returns the distance, in meters, from one lat/lng pair
to another. We use this to determine the spacing between avenues and
between streets. The result is 287 meters between Avenues and 81 meters
between streets, which is not too far from the actual
Plan
of the grid.
*/
distances = {
avenues: Ox.getDistance(points['8 & 59'], points['5 & 59']) / 3,
streets: Ox.getDistance(points['8 & 59'], points['8 & 110']) / 51
},
/*
The number of avenues and streets, in each direction, is a quarter of
the Earth's circumference divided by the respective spacing. The result
is 34,966 avenues and 123,582 streets.
*/
numbers = Ox.map(distances, function(distance) {
return C / 4 / distance;
}),
colors = {
broadway: 'rgba(0, 0, 255, 0.5)',
avenues: 'rgba(0, 255, 0, 0.5)',
streets: 'rgba(255, 0, 0, 0.5)'
},
precision = 8,
step = 10000,
$body = Ox.$('body'),
$post = Ox.$('
-90 % 360
,
which in JavaScript is -90, Ox.mod(-90, 360) returns 270.
*/
westBroadway: Ox.getPoint(
points['0 & 0'],
C / 4,
Ox.mod(bearings.broadway - 90, 360)
),
eastBroadway: Ox.getPoint(
points['0 & 0'],
C / 4,
Ox.mod(bearings.broadway + 90, 360)
)
};
/*
Now we calculate circles for Broadway, Avenues and Streets. Ox.getCircle
returns an array of lat/lng pairs that form a circle around a given point,
with a given radius and a given precision, so that the circle will have
Math.pow(2, precision)
segments.
*/
lines = {
/*
Since there is only one Broadway, this is an array with just one circle
that runs around one of the Broadway Poles, at a distance of a quarter
of the Earth's circumference.
*/
broadway: [Ox.getCircle(poles.westBroadway, C / 4, precision)],
/*
For each 10,000th avenue, we compute a circle around the East Pole.
From there, avenues range from -34,966th to 34,966th, so we start at a
distance of 966 avenues from the pole, stop once the distance is half
of the Earth's circumference (the West Pole), and in each step increase
the distance by 10,000 avenues.
*/
avenues: Ox.range(
distances.avenues * (numbers.avenues % step),
C / 2,
distances.avenues * step
).map(function(distance) {
return Ox.getCircle(poles.east, distance, precision);
}),
/*
Then we do the same for streets, starting at the South Pole.
*/
streets: Ox.range(
distances.streets * (numbers.streets % step),
C / 2,
distances.streets * step
).map(function(distance) {
return Ox.getCircle(poles.south, distance, precision);
})
};
/*
Print our data to the console.
*/
Ox.print(JSON.stringify({
bearings: bearings,
distances: distances,
numbers: numbers,
points: points,
poles: poles
}, null, ' '));
/*
Before we start drawing, we define a few helper functions.
getXYByLatLng
returns screen coordinates for a given point.
We use Ox.getXYByLatLng, which takes a lat/lng pair and returns its x/y
position on a 1x1 Mercator position, with {x: 0, y: 0}
at the
bottom left and {x: 1, y: 1}
at the top right.
*/
function getXYByLatLng(point) {
return Ox.map(Ox.getXYByLatLng(point), function(v) {
return v * mapSize;
});
}
/*
getLatLngByXY
is just the inverse, just like Ox.getLatLngByXY.
*/
function getLatLngByXY(xy) {
return Ox.getLatLngByXY(Ox.map(xy, function(v) {
return v / mapSize;
}));
}
/*
getASByLatLng
takes lat/lng and returns avenue/street. To
compute the avenue, we subtract the point's distance from the West Pole, in
avenues, from the total number of avenues. To compute the street, we
subtract the point's distance from the North Pole, in avenues, from the
total number of streets. We also return the bearing of the avenues at this
point (which form a right angle with the line from the point to the West
Pole), the bearing of the streets (at a right angle with the line to the
North Pole) and the hemisphere (east or west of Broadway).
*/
function getASByLatLng(point) {
var n = Ox.getDistance(point, poles.north),
w = Ox.getDistance(point, poles.west);
return {
avenue: numbers.avenues - w / distances.avenues,
street: numbers.streets - n / distances.streets,
bearings: {
avenues: Ox.mod(Ox.getBearing(point, poles.west) + (
w < C / 4 ? -90 : 90
), 360),
streets: Ox.mod(Ox.getBearing(point, poles.north) + (
n < C / 4 ? -90 : 90
), 360)
},
hemisphere: Ox.getDistance(point, poles.eastBroadway) < C / 4
? 'E' : 'W'
};
}
/*
getASByXY
returns avenue and street at the given screen
coordinates.
*/
function getASByXY(xy) {
return getASByLatLng(getLatLngByXY(xy));
}
/*
drawPath
draws a path of lat/lng pairs on an image. For each
path segment, we have to check if it crosses the eastern or western edge of
the map that splits the Pacific Ocean. Note that our test (a segment
crosses the edge if it spans more than 180 degrees longitude) is obviously
incorrect, but works in our case, since all segments are sufficiently
short.
*/
function drawPath(image, path, options) {
var n, parts = [[]];
/*
...
*/
path.push(path[0]);
n = path.length;
Ox.loop(n, function(i) {
var lat, lng, split;
/*
Append each point to the last part.
*/
Ox.last(parts).push(path[i]);
if (Math.abs(path[i].lng - path[(i + 1) % n].lng) > 180) {
/*
If the next line crosses the edge, get the lat/lng of the
points where the line leaves and enters the map.
*/
lat = Ox.getCenter(path[i], path[i + 1]).lat;
lng = path[i].lng < 0 ? [-180, 180] : [180, -180];
/*
Append the first point to the last part and create a new part
with the second point.
*/
Ox.last(parts).push({lat: lat, lng: lng[0]});
parts.push([{lat: lat, lng: lng[1]}]);
}
});
/*
We draw each part, translating lat/lng to [x, y].
*/
parts.forEach(function(part) {
image.drawPath(part.map(function(point) {
var xy = getXYByLatLng(point);
return [xy.x, xy.y];
}), options);
});
}
/*
...
*/
Ox.Image('jpg/earth1024.jpg', function(image) {
mapSize = image.getSize().width;
drawPath(image, Ox.getCircle(points['0 & 0'], C / 4, 8), {
color: 'rgba(255, 255, 255, 0.25)'
});
['streets', 'avenues', 'broadway'].forEach(function(type) {
lines[type].forEach(function(line, i) {
drawPath(image, line, {
color: colors[type],
width: i == lines[type].length / 2 - 0.5 ? 2 : 1
});
});
});
$body.css({
minWidth: mapSize + 'px',
height: mapSize + 'px',
backgroundImage: 'url(' + image.src() + ')'
})
.bind({
click: click,
mouseover: mouseover,
mousemove: mousemove,
mouseout: mouseout
});
[
{point: points['0 & 0'], title: 'Manhattan', z: 12},
{point: {lat: 48.87377, lng: 2.29505}, title: 'Paris', z: 13},
{point: poles.north, title: 'Uzbekistan', z: 14}
].forEach(function(marker, i) {
var as = getASByLatLng(marker.point),
g = {s: 256, v: 108, z: marker.z},
xy = getXYByLatLng(marker.point);
Ox.print(as)
Ox.extend(g, Ox.map(Ox.getXYByLatLng(marker.point), function(v) {
return Math.floor(v * Math.pow(2, g.z));
}));
Ox.$('