|
<!DOCTYPE html> |
|
<html> |
|
<head> |
|
<meta http-equiv="Content-Type" content="text/html;charset=utf-8"> |
|
<title>Z-Order Curve</title> |
|
<script src="http://d3js.org/d3.v3.min.js"></script> |
|
<style type="text/css"> |
|
|
|
body { |
|
background: #fff; |
|
} |
|
|
|
.brush .extent { |
|
stroke: #fff; |
|
fill-opacity: .125; |
|
shape-rendering: crispEdges; |
|
} |
|
|
|
</style> |
|
</head> |
|
<body> |
|
<script type="text/javascript"> |
|
|
|
var w = 1200, |
|
h = 800, |
|
scale = 8; |
|
|
|
var brush = d3.svg.brush() |
|
.x(d3.scale.identity().domain([0, w])) |
|
.y(d3.scale.identity().domain([0, h])) |
|
.on("brush", brushed) |
|
.extent([[100, 100], [200, 200]]); |
|
|
|
// http://stackoverflow.com/questions/4909263/how-to-efficiently-de-interleave-bits-inverse-morton |
|
deinterleave = function(x) |
|
{ |
|
x = x & 0x55555555; |
|
x = (x | (x >> 1)) & 0x33333333; |
|
x = (x | (x >> 2)) & 0x0F0F0F0F; |
|
x = (x | (x >> 4)) & 0x00FF00FF; |
|
x = (x | (x >> 8)) & 0x0000FFFF; |
|
return x; |
|
} |
|
|
|
// http://graphics.stanford.edu/~seander/bithacks.html#InterleaveBMN |
|
interleave = function(x, y) { |
|
|
|
var B = [0x55555555, 0x33333333, 0x0F0F0F0F, 0x00FF00FF]; |
|
var S = [1, 2, 4, 8]; |
|
|
|
x = (x | (x << S[3])) & B[3]; |
|
x = (x | (x << S[2])) & B[2]; |
|
x = (x | (x << S[1])) & B[1]; |
|
x = (x | (x << S[0])) & B[0]; |
|
|
|
y = (y | (y << S[3])) & B[3]; |
|
y = (y | (y << S[2])) & B[2]; |
|
y = (y | (y << S[1])) & B[1]; |
|
y = (y | (y << S[0])) & B[0]; |
|
|
|
z = x | (y << 1); |
|
return z; |
|
} |
|
|
|
// Builds the x,y points for the z curve with the given range of values |
|
buildCurve = function(startZ, endZ) { |
|
|
|
var curve = []; |
|
|
|
for ( var z = startZ; z < endZ; ++z ) { |
|
var x = deinterleave(z); |
|
var y = deinterleave(z >> 1); |
|
curve.push( {"x" : x*scale, "y" : y*scale} ); |
|
} |
|
|
|
return curve; |
|
} |
|
|
|
var lineFunction = d3.svg.line() |
|
.x(function(d) { return d.x; }) |
|
.y(function(d) { return d.y; }) |
|
.interpolate("linear"); |
|
|
|
var svg = d3.select("body").append("svg") |
|
.attr("width", w) |
|
.attr("height", h); |
|
|
|
svg.append("path") |
|
.attr("d", lineFunction( buildCurve(0, 30000) )) |
|
.attr("stroke", "#333") |
|
.attr("stroke-width", 1) |
|
.attr("fill", "none"); |
|
|
|
svg.append("path") |
|
.attr("class", "scanned") |
|
.attr("stroke", "#f00") |
|
.attr("stroke-width", 1) |
|
.attr("fill", "none"); |
|
|
|
svg.append("g") |
|
.attr("class", "brush") |
|
.call(brush); |
|
|
|
brushed(); |
|
|
|
function brushed() { |
|
var extent = brush.extent(); |
|
|
|
// get the z values for the extent |
|
zUL = zFromPoint( Math.round(extent[0][0]/scale), Math.round(extent[0][1]/scale) ); |
|
zLR = zFromPoint( Math.round(extent[1][0]/scale), Math.round(extent[1][1]/scale) ); |
|
|
|
// Set the data for the scanned path |
|
svg.selectAll(".scanned") |
|
.attr("d", lineFunction( buildCurve(zUL, zLR) )) |
|
} |
|
|
|
function zFromPoint(x, y) { |
|
return interleave(x, y); |
|
} |
|
|
|
</script> |
|
</body> |
|
</html> |
