D3 3.0 supports three-axis rotation for geographic projections. This example demonstrates rotating lambda (λ), phi (φ) and gamma (γ) in three side-by-side bottomley projections.
forked from mbostock's block: Three-Axis Rotation
-
-
Save Fil/df0afe191dc666d9d2c0 to your computer and use it in GitHub Desktop.
Three-Axis Bottomley Rotation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| <!DOCTYPE html> | |
| <meta charset="utf-8"> | |
| <style> | |
| .title { | |
| display: inline-block; | |
| font-size: 48px; | |
| line-height: 90px; | |
| text-align: center; | |
| } | |
| </style> | |
| <body> | |
| <script src="//d3js.org/d3.v3.min.js"></script> | |
| <script src="//d3js.org/topojson.v1.min.js"></script> | |
| <script> | |
| var π = Math.PI, halfπ=π/2; | |
| function bottomleyRaw(ψ) { | |
| function forward(λ, φ) { | |
| var ρ = halfπ - φ, | |
| η = ρ ? λ * Math.sin(ψ) * Math.sin(ρ) / ρ : ρ; | |
| return [ | |
| ρ * Math.sin(η) / Math.sin(ψ), | |
| halfπ - ρ * Math.cos(η) | |
| ]; | |
| } | |
| forward.invert = function(x, y) { | |
| var x1 = x * Math.sin(ψ), | |
| y1 = halfπ - y; | |
| var ρ = Math.sqrt( x1 * x1 + y1 * y1 ), | |
| η = Math.atan( x1 / y1 ); | |
| return [ | |
| (ρ ? ρ / Math.sin(ρ) : 1) * η / Math.sin(ψ), | |
| halfπ - ρ | |
| ]; | |
| }; | |
| return forward; | |
| } | |
| (d3.geo.bottomley = function() { | |
| var ψ = π/6, | |
| mutate = d3.geo.projectionMutator(bottomleyRaw), | |
| projection = mutate(ψ); | |
| projection.variant = function(_) { | |
| if (!arguments.length) return ψ; | |
| return mutate(ψ = _); | |
| }; | |
| return projection; | |
| }).raw = bottomleyRaw; | |
| var diameter = 960 / 3, | |
| radius = diameter >> 1, | |
| velocity = .01, | |
| then = Date.now(); | |
| var projection = d3.geo.bottomley() | |
| .scale(radius/2 - 2) | |
| .translate([radius, radius]) | |
| //.clipAngle(90) | |
| .precision(0); | |
| d3.select("body").selectAll(".title") | |
| .data(["λ", "φ", "γ"]) | |
| .enter().append("div") | |
| .attr("class", "title") | |
| .style("width", diameter + "px") | |
| .text(function(d) { return d; }); | |
| var canvas = d3.select("body").selectAll("canvas") | |
| .data(d3.range(3)) | |
| .enter().append("canvas") | |
| .attr("width", diameter) | |
| .attr("height", diameter); | |
| var path = d3.geo.path() | |
| .projection(projection); | |
| d3.json("https://gist.githubusercontent.com/mbostock/4090846/raw/d534aba169207548a8a3d670c9c2cc719ff05c47/world-110m.json", function(error, world) { | |
| if (error) throw error; | |
| var land = topojson.feature(world, world.objects.land), | |
| globe = {type: "Sphere"}; | |
| d3.timer(function() { | |
| var angle = velocity * (Date.now() - then); | |
| canvas.each(function(i) { | |
| var rotate = [0, 0, 0], context = this.getContext("2d"); | |
| rotate[i] = angle, projection.rotate(rotate); | |
| context.clearRect(0, 0, diameter, diameter); | |
| context.beginPath(), path.context(context)(land), context.fill(); | |
| context.beginPath(), path(globe), context.stroke(); | |
| }); | |
| }); | |
| }); | |
| </script> |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment