Stash original

sweep.js

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+var Canvas = require('canvas'),
+    Image = Canvas.Image,
+    fs = require('fs'),
+    canvas = new Canvas(980,980),
+    ctx = canvas.getContext('2d');
+
+var d3_radians = Math.PI / 180;
+// TODO clip input coordinates on opposite hemisphere
+var azimuthal = function() {
+  var mode = "orthographic", // or stereographic
+      origin,
+      scale = 200,
+      translate = [480, 250],
+      x0,
+      y0,
+      cy0,
+      sy0;
+
+  function azimuthal(coordinates) {
+    var x1 = coordinates[0] * d3_radians - x0,
+        y1 = coordinates[1] * d3_radians,
+        cx1 = Math.cos(x1),
+        sx1 = Math.sin(x1),
+        cy1 = Math.cos(y1),
+        sy1 = Math.sin(y1),
+        k = mode === "stereographic" ? 1 / (1 + sy0 * sy1 + cy0 * cy1 * cx1) : 1,
+        x = k * cy1 * sx1,
+        y = k * (sy0 * cy1 * cx1 - cy0 * sy1);
+    return [
+      scale * x + translate[0],
+      scale * y + translate[1]
+    ];
+  }
+
+  azimuthal.invert = function(coordinates) {
+    var x = (coordinates[0] - translate[0]) / scale,
+        y = (coordinates[1] - translate[1]) / scale,
+        p = Math.sqrt(x * x + y * y),
+        c = mode === "stereographic" ? 2 * Math.atan(p) : Math.asin(p),
+        sc = Math.sin(c),
+        cc = Math.cos(c);
+    return [
+      (x0 + Math.atan2(x * sc, p * cy0 * cc + y * sy0 * sc)) / d3_radians,
+      Math.asin(cc * sy0 - (y * sc * cy0) / p) / d3_radians
+    ];
+  };
+
+  azimuthal.mode = function(x) {
+    if (!arguments.length) return mode;
+    mode = x + "";
+    return azimuthal;
+  };
+
+  azimuthal.origin = function(x) {
+    if (!arguments.length) return origin;
+    origin = x;
+    x0 = origin[0] * d3_radians;
+    y0 = origin[1] * d3_radians;
+    cy0 = Math.cos(y0);
+    sy0 = Math.sin(y0);
+    return azimuthal;
+  };
+
+  azimuthal.scale = function(x) {
+    if (!arguments.length) return scale;
+    scale = +x;
+    return azimuthal;
+  };
+
+  azimuthal.translate = function(x) {
+    if (!arguments.length) return translate;
+    translate = [+x[0], +x[1]];
+    return azimuthal;
+  };
+
+  return azimuthal.origin([0, 0]);
+};
+
+var mercator = function() {
+  var scale = 500,
+      translate = [480, 250];
+
+  function mercator(coordinates) {
+    var x = coordinates[0] / 360,
+        y = -(Math.log(Math.tan(Math.PI / 4 + coordinates[1] * d3_radians / 2)) / d3_radians) / 360;
+    return [
+      scale * x + translate[0],
+      scale * Math.max(-.5, Math.min(.5, y)) + translate[1]
+    ];
+  }
+
+  mercator.invert = function(coordinates) {
+    var x = (coordinates[0] - translate[0]) / scale,
+        y = (coordinates[1] - translate[1]) / scale;
+    return [
+      360 * x,
+      2 * Math.atan(Math.exp(-360 * y * d3_radians)) / d3_radians - 90
+    ];
+  };
+
+  mercator.scale = function(x) {
+    if (!arguments.length) return scale;
+    scale = +x;
+    return mercator;
+  };
+
+  mercator.translate = function(x) {
+    if (!arguments.length) return translate;
+    translate = [+x[0], +x[1]];
+    return mercator;
+  };
+
+  return mercator;
+};
+
+
+var fcanvas = new Canvas(600,300),
+    fctx = fcanvas.getContext('2d');
+
+var merc = mercator()
+    .scale(400)
+    .translate([200, 200]);
+
+var ortho = azimuthal()
+      .scale(130)
+      .origin([0, 40])
+      .mode("orthographic")
+      .translate([140, 140]);
+
+var pts = [];
+var colors = [];
+
+for (var x = -180; x <= 180; x += 1) {
+    for (var y = -90; y <= 90; y += 1) {
+        pts.push({coord: [x, y]});
+    }
+}
+
+fs.readFile(__dirname + '/bm.jpeg', function(err, im){
+    img = new Image();
+    img.src = im;
+    fctx.drawImage(img, 0, 0, 600, 300);
+    var w = 600;
+    var imgData = fctx.getImageData(0, 0, fcanvas.width, fcanvas.height);
+    var data = imgData.data;
+
+    for (var i = 0; i < pts.length; i++) {
+        // var x = Math.round(((~pts[i].coord[0] + 180) / 360) * 600);
+        // var y = Math.round(((-pts[i].coord[1] + 90) / 180) * 300);
+        var x = -pts[i].coord[0] + 180;
+        var y = -pts[i].coord[1] + 90;
+        var r = data[4 * (y * w + x) + 0],
+            g = data[4 * (y * w + x) + 1],
+            b = data[4 * (y * w + x) + 2];
+        pts[i].color = 'rgb(' + [r, g, b].join(',') + ')';
+    }
+    draw();
+});
+
+
+function draw() {
+
+    ctx.fillStyle = "#000000";
+    ctx.fillRect(0, 0, 480, 320);
+
+
+    for (var i = 0; i < pts.length; i++) {
+        var px = merc(pts[i].coord);
+        ctx.fillStyle = pts[i].color;
+        console.log(px);
+        ctx.fillRect(px[0], px[1], 1, 1);
+    }
+
+    var fs = require('fs'),
+        out = fs.createWriteStream(__dirname + '/test.png'),
+        stream = canvas.createPNGStream();
+
+    stream.on('data', function(chunk){
+      out.write(chunk);
+    });
+
+    stream.on('end', function(){
+      console.log('saved png');
+    });
+}
+
+// console.log(merc([0, 5]));