Fix #45 - better default scales.

package.json

@@ -32,6 +32,7 @@
   },
   "devDependencies": {
     "canvas": "1",
+    "d3-format": "1",
     "eslint": "2",
     "package-preamble": "0.0",
     "rollup": "0.33",

src/projection/azimuthalEqualArea.js

@@ -12,6 +12,6 @@ azimuthalEqualAreaRaw.invert = azimuthalInvert(function(z) {
 
 export default function() {
   return projection(azimuthalEqualAreaRaw)
-      .scale(120)
+      .scale(124.75)
       .clipAngle(180 - 1e-3);
 }

src/projection/azimuthalEquidistant.js

@@ -1,4 +1,4 @@
-import {acos, sin, tau} from "../math";
+import {acos, sin} from "../math";
 import {azimuthalRaw, azimuthalInvert} from "./azimuthal";
 import projection from "./index";
 
@@ -12,6 +12,6 @@ azimuthalEquidistantRaw.invert = azimuthalInvert(function(z) {
 
 export default function() {
   return projection(azimuthalEquidistantRaw)
-      .scale(480 / tau)
+      .scale(79.4188)
       .clipAngle(180 - 1e-3);
 }

src/projection/conicConformal.js

@@ -29,5 +29,6 @@ export function conicConformalRaw(y0, y1) {
 }
 
 export default function() {
-  return conicProjection(conicConformalRaw);
+  return conicProjection(conicConformalRaw)
+      .scale(131.8);
 }

src/projection/conicEqualArea.js

@@ -22,6 +22,6 @@ export function conicEqualAreaRaw(y0, y1) {
 
 export default function() {
   return conicProjection(conicEqualAreaRaw)
-      .scale(151)
-      .translate([480, 347]);
+      .scale(155.424)
+      .center([0, 33.6442]);
 }

src/projection/conicEquidistant.js

@@ -24,6 +24,6 @@ export function conicEquidistantRaw(y0, y1) {
 
 export default function() {
   return conicProjection(conicEquidistantRaw)
-      .scale(128)
-      .translate([480, 280]);
+      .scale(131.154)
+      .center([0, 13.9389]);
 }

src/projection/equirectangular.js

@@ -1,4 +1,3 @@
-import {pi} from "../math";
 import projection from "./index";
 
 export function equirectangularRaw(lambda, phi) {
@@ -8,5 +7,6 @@ export function equirectangularRaw(lambda, phi) {
 equirectangularRaw.invert = equirectangularRaw;
 
 export default function() {
-  return projection(equirectangularRaw).scale(480 / pi);
+  return projection(equirectangularRaw)
+      .scale(152.63);
 }

src/projection/gnomonic.js

@@ -11,6 +11,6 @@ gnomonicRaw.invert = azimuthalInvert(atan);
 
 export default function() {
   return projection(gnomonicRaw)
-      .scale(139)
+      .scale(144.049)
       .clipAngle(60);
 }

src/projection/mercator.js

@@ -10,7 +10,8 @@ mercatorRaw.invert = function(x, y) {
 };
 
 export default function() {
-  return mercatorProjection(mercatorRaw);
+  return mercatorProjection(mercatorRaw)
+      .scale(961 / tau);
 }
 
 export function mercatorProjection(project) {
@@ -31,12 +32,13 @@ export function mercatorProjection(project) {
   m.clipExtent = function(_) {
     if (!arguments.length) return clipAuto ? null : clipExtent();
     if (clipAuto = _ == null) {
-      var k = pi * scale(), t = translate();
+      var k = pi * scale(),
+          t = translate();
       _ = [[t[0] - k, t[1] - k], [t[0] + k, t[1] + k]];
     }
     clipExtent(_);
     return m;
   };
 
-  return m.clipExtent(null).scale(961 / tau);
+  return m.clipExtent(null);
 }

src/projection/orthographic.js

@@ -10,6 +10,6 @@ orthographicRaw.invert = azimuthalInvert(asin);
 
 export default function() {
   return projection(orthographicRaw)
-      .scale(240)
+      .scale(249.5)
       .clipAngle(90 + epsilon);
 }

src/projection/stereographic.js

@@ -13,6 +13,6 @@ stereographicRaw.invert = azimuthalInvert(function(z) {
 
 export default function() {
   return projection(stereographicRaw)
-      .scale(240)
+      .scale(250)
       .clipAngle(142);
 }

src/projection/transverseMercator.js

@@ -22,5 +22,6 @@ export default function() {
     return arguments.length ? rotate([_[0], _[1], _.length > 2 ? _[2] + 90 : 90]) : (_ = rotate(), [_[0], _[1], _[2] - 90]);
   };
 
-  return rotate([0, 0, 90]);
+  return rotate([0, 0, 90])
+      .scale(159.155);
 }

test/compute-scale

@@ -0,0 +1,47 @@
+#!/usr/bin/env node
+
+var width = 960 - 1,
+    height = 500 - 1,
+    projectionName = process.argv[2],
+    projectionSymbol = "geo" + projectionName[0].toUpperCase() + projectionName.slice(1);
+
+if (!/^[a-z0-9]+$/i.test(projectionName)) throw new Error;
+
+var topojson = require("topojson"),
+    d3_format = require("d3-format"),
+    d3_geo = require("../");
+
+var formatNumber = d3_format.format(".6");
+
+var projection = d3_geo[projectionSymbol]()
+    .precision(0.01)
+    .scale(1)
+    .translate([0, 0])
+    .center([0, 0]);
+
+if (projection.rotate) projection.rotate([0, 0]);
+
+var land = {type: "Sphere"};
+
+switch (projectionName) {
+  case "conicConformal":
+  case "stereographic": {
+    projection.clipAngle(90);
+    break;
+  }
+}
+
+var path = d3_geo.geoPath()
+    .projection(projection);
+
+var bounds = path.bounds(land),
+    dx = bounds[1][0] - bounds[0][0],
+    dy = bounds[1][1] - bounds[0][1],
+    cx = (bounds[1][0] + bounds[0][0]) / 2,
+    cy = (bounds[1][1] + bounds[0][1]) / 2,
+    scale = Math.min(width / dx, height / dy);
+
+console.log(`d3.${projectionSymbol}()
+    .scale(${formatNumber(scale)})
+    .center([${(projection.invert ? projection.invert([cx, cy]) : [0, 0]).map(formatNumber).join(", ")}]);
+`);

test/render-us

@@ -18,7 +18,7 @@ var canvas = new Canvas(width, height),
 var us = require("./data/us-10m.json");
 
 var path = d3_geo.geoPath()
-    .projection(d3_geo[projectionSymbol]())
+    .projection(d3_geo[projectionSymbol]().precision(0.1))
     .context(context);
 
 context.fillStyle = "#fff";

test/render-world

@@ -15,16 +15,30 @@ var fs = require("fs"),
 var canvas = new Canvas(width, height),
     context = canvas.getContext("2d");
 
-var world = require("./data/world-50m.json");
+var world = require("./data/world-50m.json"),
+    graticule = d3_geo.geoGraticule(),
+    outline = {type: "Sphere"};
 
-var graticule = d3_geo.geoGraticule();
+// switch (projectionName) {
+//   case "littrow": outline = graticule.extent([[-90, -60], [90, 60]]).outline(); break;
+// }
 
 var path = d3_geo.geoPath()
     .projection(d3_geo[projectionSymbol]().precision(0.1))
     .context(context);
 
 context.fillStyle = "#fff";
 context.fillRect(0, 0, width, height);
+context.save();
+
+// switch (projectionName) {
+//   case "armadillo": {
+//     context.beginPath();
+//     path(outline);
+//     context.clip();
+//     break;
+//   }
+// }
 
 context.beginPath();
 path(topojson.feature(world, world.objects.land));
@@ -36,8 +50,10 @@ path(graticule());
 context.strokeStyle = "rgba(119,119,119,0.5)";
 context.stroke();
 
+context.restore();
+
 context.beginPath();
-path({type: "Sphere"});
+path(outline);
 context.strokeStyle = "#000";
 context.stroke();