Building on this - experimenting with fake 3d svg arcs using two nested orthographic projections and cardinal line interpolation.
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March 28, 2023 23:31
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Faux-3D Arcs
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<!DOCTYPE html> | |
<meta charset="utf-8"> | |
<style> | |
.land { | |
fill: #999; | |
stroke-opacity: 1; | |
} | |
.graticule { | |
fill: none; | |
stroke: black; | |
stroke-width:.5; | |
opacity:.2; | |
} | |
.labels { | |
font: 8px sans-serif; | |
fill: black; | |
opacity: .5; | |
display:none; | |
} | |
.noclicks { pointer-events:none; } | |
.point { opacity:.6; } | |
.arcs { | |
opacity:.1; | |
stroke: gray; | |
stroke-width: 3; | |
} | |
.flyers { | |
stroke-width:1; | |
opacity: .6; | |
stroke: darkred; | |
} | |
.arc, .flyer { | |
stroke-linejoin: round; | |
fill:none; | |
} | |
.arc { } | |
.flyer { } | |
.flyer:hover { } | |
</style> | |
<body> | |
<script src="http://d3js.org/d3.v3.min.js"></script> | |
<script src="http://d3js.org/queue.v1.min.js"></script> | |
<script src="http://d3js.org/topojson.v0.min.js"></script> | |
<script> | |
d3.select(window) | |
.on("mousemove", mousemove) | |
.on("mouseup", mouseup); | |
var width = 960, | |
height = 500; | |
var proj = d3.geo.orthographic() | |
.translate([width / 2, height / 2]) | |
.clipAngle(90) | |
.scale(220); | |
var sky = d3.geo.orthographic() | |
.translate([width / 2, height / 2]) | |
.clipAngle(90) | |
.scale(300); | |
var path = d3.geo.path().projection(proj).pointRadius(2); | |
var swoosh = d3.svg.line() | |
.x(function(d) { return d[0] }) | |
.y(function(d) { return d[1] }) | |
.interpolate("cardinal") | |
.tension(.0); | |
var links = [], | |
arcLines = []; | |
var svg = d3.select("body").append("svg") | |
.attr("width", width) | |
.attr("height", height) | |
.on("mousedown", mousedown); | |
queue() | |
.defer(d3.json, "/d/4686432/world-110m.json") | |
.defer(d3.json, "places.json") | |
.await(ready); | |
function ready(error, world, places) { | |
var ocean_fill = svg.append("defs").append("radialGradient") | |
.attr("id", "ocean_fill") | |
.attr("cx", "75%") | |
.attr("cy", "25%"); | |
ocean_fill.append("stop").attr("offset", "5%").attr("stop-color", "#fff"); | |
ocean_fill.append("stop").attr("offset", "100%").attr("stop-color", "#ababab"); | |
var globe_highlight = svg.append("defs").append("radialGradient") | |
.attr("id", "globe_highlight") | |
.attr("cx", "75%") | |
.attr("cy", "25%"); | |
globe_highlight.append("stop") | |
.attr("offset", "5%").attr("stop-color", "#ffd") | |
.attr("stop-opacity","0.6"); | |
globe_highlight.append("stop") | |
.attr("offset", "100%").attr("stop-color", "#ba9") | |
.attr("stop-opacity","0.2"); | |
var globe_shading = svg.append("defs").append("radialGradient") | |
.attr("id", "globe_shading") | |
.attr("cx", "55%") | |
.attr("cy", "45%"); | |
globe_shading.append("stop") | |
.attr("offset","30%").attr("stop-color", "#fff") | |
.attr("stop-opacity","0") | |
globe_shading.append("stop") | |
.attr("offset","100%").attr("stop-color", "#505962") | |
.attr("stop-opacity","0.3") | |
var drop_shadow = svg.append("defs").append("radialGradient") | |
.attr("id", "drop_shadow") | |
.attr("cx", "50%") | |
.attr("cy", "50%"); | |
drop_shadow.append("stop") | |
.attr("offset","20%").attr("stop-color", "#000") | |
.attr("stop-opacity",".5") | |
drop_shadow.append("stop") | |
.attr("offset","100%").attr("stop-color", "#000") | |
.attr("stop-opacity","0") | |
svg.append("ellipse") | |
.attr("cx", 440).attr("cy", 450) | |
.attr("rx", proj.scale()*.90) | |
.attr("ry", proj.scale()*.25) | |
.attr("class", "noclicks") | |
.style("fill", "url(#drop_shadow)"); | |
svg.append("circle") | |
.attr("cx", width / 2).attr("cy", height / 2) | |
.attr("r", proj.scale()) | |
.attr("class", "noclicks") | |
.style("fill", "url(#ocean_fill)"); | |
svg.append("path") | |
.datum(topojson.object(world, world.objects.land)) | |
.attr("class", "land noclicks") | |
.attr("d", path); | |
svg.append("circle") | |
.attr("cx", width / 2).attr("cy", height / 2) | |
.attr("r", proj.scale()) | |
.attr("class","noclicks") | |
.style("fill", "url(#globe_highlight)"); | |
svg.append("circle") | |
.attr("cx", width / 2).attr("cy", height / 2) | |
.attr("r", proj.scale()) | |
.attr("class","noclicks") | |
.style("fill", "url(#globe_shading)"); | |
svg.append("g").attr("class","points") | |
.selectAll("text").data(places.features) | |
.enter().append("path") | |
.attr("class", "point") | |
.attr("d", path); | |
// spawn links between cities as source/target coord pairs | |
places.features.forEach(function(a) { | |
places.features.forEach(function(b) { | |
if (a !== b) { | |
links.push({ | |
source: a.geometry.coordinates, | |
target: b.geometry.coordinates | |
}); | |
} | |
}); | |
}); | |
// build geoJSON features from links array | |
links.forEach(function(e,i,a) { | |
var feature = { "type": "Feature", "geometry": { "type": "LineString", "coordinates": [e.source,e.target] }} | |
arcLines.push(feature) | |
}) | |
svg.append("g").attr("class","arcs") | |
.selectAll("path").data(arcLines) | |
.enter().append("path") | |
.attr("class","arc") | |
.attr("d",path) | |
svg.append("g").attr("class","flyers") | |
.selectAll("path").data(links) | |
.enter().append("path") | |
.attr("class","flyer") | |
.attr("d", function(d) { return swoosh(flying_arc(d)) }) | |
refresh(); | |
} | |
function flying_arc(pts) { | |
var source = pts.source, | |
target = pts.target; | |
var mid = location_along_arc(source, target, .5); | |
var result = [ proj(source), | |
sky(mid), | |
proj(target) ] | |
return result; | |
} | |
function refresh() { | |
svg.selectAll(".land").attr("d", path); | |
svg.selectAll(".point").attr("d", path); | |
svg.selectAll(".arc").attr("d", path) | |
.attr("opacity", function(d) { | |
return fade_at_edge(d) | |
}) | |
svg.selectAll(".flyer") | |
.attr("d", function(d) { return swoosh(flying_arc(d)) }) | |
.attr("opacity", function(d) { | |
return fade_at_edge(d) | |
}) | |
} | |
function fade_at_edge(d) { | |
var centerPos = proj.invert([width/2,height/2]), | |
arc = d3.geo.greatArc(), | |
start, end; | |
// function is called on 2 different data structures.. | |
if (d.source) { | |
start = d.source, | |
end = d.target; | |
} | |
else { | |
start = d.geometry.coordinates[0]; | |
end = d.geometry.coordinates[1]; | |
} | |
var start_dist = 1.57 - arc.distance({source: start, target: centerPos}), | |
end_dist = 1.57 - arc.distance({source: end, target: centerPos}); | |
var fade = d3.scale.linear().domain([-.1,0]).range([0,.1]) | |
var dist = start_dist < end_dist ? start_dist : end_dist; | |
return fade(dist) | |
} | |
function location_along_arc(start, end, loc) { | |
var interpolator = d3.geo.interpolate(start,end); | |
return interpolator(loc) | |
} | |
// modified from http://bl.ocks.org/1392560 | |
var m0, o0; | |
function mousedown() { | |
m0 = [d3.event.pageX, d3.event.pageY]; | |
o0 = proj.rotate(); | |
d3.event.preventDefault(); | |
} | |
function mousemove() { | |
if (m0) { | |
var m1 = [d3.event.pageX, d3.event.pageY] | |
, o1 = [o0[0] + (m1[0] - m0[0]) / 6, o0[1] + (m0[1] - m1[1]) / 6]; | |
o1[1] = o1[1] > 30 ? 30 : | |
o1[1] < -30 ? -30 : | |
o1[1]; | |
proj.rotate(o1); | |
sky.rotate(o1); | |
refresh(); | |
} | |
} | |
function mouseup() { | |
if (m0) { | |
mousemove(); | |
m0 = null; | |
} | |
} | |
</script> |
Very cool! Here's a version which avoids the need for the nested sky projection, and makes arc "flying height" proportional to length.
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Spectacular work!
How would you go about linking only specific points rather than all as a mesh?
Regards