D3 Examples - D3.js + Orthographic Projection

D3.js + Orthographic Projection
D3 Visualization: Places Traveled
This gist was originally created to illustrate the data scrubbing process, and all files are associated with my blog post under the same name.
The file progression proceeds from data.txt, a simple text document which contains a list of places, to formatting this original data set as GeoJSON, data.geojson.
Once formatted as GeoJSON, we use D3.js to visualize the data, drawing inspiration from similar visualizations utilizing the same framework.
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<!DOCTYPE html>
<html>
  <head>
        <meta charset="utf-8">
        <style>
            body {
                width: 100%;
                height: 100%;
                margin: 0;
            }
​
            .geo-globe {
                fill: rgba(0,0,0,0.1);
            }
​
            .geo-path {
                fill: #132A50; 
                stroke: #FFFFFF;
                stroke-width: 0.2;
            }
​
                .geo-path:hover {
                    fill: #3B5998;
                }
​
            .geo-node {
                stroke-width: 0.0;
                stroke: rgba(255, 0, 10, 0.66); 
                fill: rgba(255, 0, 10, 0.66); 
                
                cursor: pointer;                
            }
​
                .geo-node:hover {
                    stroke: #a00;
                    fill: #a00;
                }
        </style>
        <script type="text/javascript" src="https://code.jquery.com/jquery-1.9.1.min.js"></script>
        <script type="text/javascript" src="https://d3js.org/d3.v3.min.js" charset="utf-8"></script>
    </head>
    <body>
        <script>
            // Initialize some variables:
            var element = 'body',
                  width = $(document).width(),
                  height = $(document).height();
​
            var radius = 10,    // px
                hoverRadius = 20; // px
​
            var features, circles;
            
            // Define the type of map projection we want: (see https://github.com/mbostock/d3/wiki/Geo-Projections)
        var projection = d3.geo.orthographic()
            .scale(250) // scale the map
            .translate([width / 2, height / 2]) // set the center of the map to be the center of the canvas
            .clipAngle(90);
​
            // Save the path generator for the current projection:
            var path = d3.geo.path()
                .projection(projection)
                .pointRadius( function(d,i) {
                    return radius;
                });
​
            // Define the longitude and latitude scales, which allow us to map lon/lat coordinates to pixel values:
            var lambda = d3.scale.linear()
                .domain([0, width])
                .range([-180, 180]);
​
            var phi = d3.scale.linear()
                .domain([0, height])
                .range([90, -90]);
​
            // Create the drawing canvas:
            var svg = d3.select("body").append("svg:svg")
                .attr("width", '100%')
                .attr("height", '100%');
​
            //Create a base circle: (could use this to color oceans)
          var backgroundCircle = svg.append("svg:circle")
            .attr('cx', width / 2)
            .attr('cy', height / 2)
            .attr('r', 0)
            .attr('class', 'geo-globe');
                                
            // Make a <g> tag to group all our countries, which is useful for zoom purposes. (child elements belong to a 'group', which we can zoom all-at-once)
        var world = svg.append('svg:g');
        var zoomScale = 1; // default  
        
        // Create the element group to mark individual locations:
        var locations = svg.append('svg:g')
            .attr('id', 'locations');
​
        // Having defined the projection, update the backgroundCircle radius:
            backgroundCircle.attr('r', projection.scale() );
​
            
        // Construct our world map based on the projection:
        d3.json('data/world-countries.json', function(collection) { 
             
            features = world.selectAll('path')
                .data(collection.features)
                .enter()
                .append('svg:path')
                    .attr('class', 'geo-path')
                    .attr('d', path); 
            
            features.append('svg:title')
                .text( function(d) { return d.properties.name; });
               
            }); // end FUNCTION d3.json()
​
        // Load our location data:
        d3.json('data/data.geojson', function(collection) {
​
              // Plot the positions on the map:
        circles = locations.selectAll('path')
            .data(collection.features)
            .enter()
            .append('svg:path')
                .attr('class', 'geo-node')
                .attr('d', path)
                .on('mouseover', mouseover)
                .on('mouseout', mouseout);
  
        circles.append('svg:title')
            .text( function(d) { return d.properties.name; } );
​
            }); // end FUNCTION d3.json()            
​
            // Specify a few event handlers to allow globe rotation:
            d3.select(window)
                .on("mousemove", mousemove)
                .on("mouseup", mouseup);
            
            svg.on('mousedown', mousedown);
​
            // Setup zoom behavior:
        var zoom = d3.behavior.zoom(true)
            .scale( projection.scale() )
            .scaleExtent([100, 800])
            .on("zoom", globeZoom);
​
        svg.call(zoom)
            .on('dblclick.zoom', null);
​
​
        // MOUSE EVENTS //
​
        var mousePos;
        
        function mouseover(d, i) {
                
            path.pointRadius( function(d,i) {
                return hoverRadius;
            });
            
            // Increase the circle radius, so the user knows she is hovering over this node:
        d3.select(this).attr('d', path);                        
            
        }; // end FUNCTION mouseover(d,i)
        
        function mouseout(d, i) {
            
            path.pointRadius( function(d,i) {
                return radius;
            });
            
            // Reduce the circle radius to its pre-mouseover state:
        d3.select(this).attr('d', path);   
            
        }; // end FUNCTION mouseout(d,i)
        
        function mousedown() {
        
            // Determine mouse pixel coordinates:
            mousePos = [d3.event.pageX, d3.event.pageY];
            
            // Prevent the default behavior for mouse down events:
            d3.event.preventDefault();
              
            }; // end FUNCTION mousedown()
            
            function mousemove() {
​
                // Has the mouse button been released?
            if (mousePos) {
                
                var p = d3.mouse(svg[0][0]);
                projection.rotate([lambda(p[0]), phi(p[1])]);
                svg.selectAll("path").attr("d", path);
                
            };
              
            }; // end FUNCTION mousemouse()
            
            function mouseup() {
                
                // Do we have mouse coordinates? 
              if (mousePos) {
                
                // Yes, so update the map based on the final mouse coordinates and clear the mouse position:        
                mousemove();
                mousePos = null;
                
              }; 
              
            }; // end FUNCTION mouseup()
            
            
            
        // Helper functions //
            
            function globeZoom() {
                if (d3.event) {
                    var _scale = d3.event.scale;
​
                    projection.scale(_scale);
                    backgroundCircle.attr('r', _scale);
                    path.pointRadius( radius );
​
                    features.attr('d', path);
                    circles.attr('d', path); 
​
                }; // end IF
            };
        </script>
    </body>
</html>
​
    