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<html>
    <head>
        <meta charset="utf-8">
        <meta name="viewport" content="width=device-width, initial-scale=1" />
        <script src="https://unpkg.com/d3-array@3"></script>
        <script src="https://unpkg.com/d3-geo@3/dist/d3-geo.js"></script>

        <script src="lib/simpleRequire.js"></script>
        <script src="lib/config.js"></script>
        <script src="lib/jquery.min.js"></script>
        <script src="lib/facePrint.js"></script>
        <script src="lib/testHelper.js"></script>
        <script src="lib/dat.gui.min.js"></script>

        <!-- <script src="ut/lib/canteen.js"></script> -->
        <link rel="stylesheet" href="lib/reset.css" />
    </head>
    <body>
        <style>
            body {
                margin: 0;
            }
            #main {
                position: absolute;
                left: 0;
                top: 0;
                bottom: 0;
                right: 0;
            }
        </style>


        <div id="main"></div>


        <script>
        require([
            'echarts',
            './data/map/json/world.json',
            './data/usa.json'
        ], function (echarts, worldJson, usaJson) {

            var d3Projections =  [
                ['default'],
                // Azimuthal Projections
                ['geoAzimuthalEqualArea'],
                ['geoAzimuthalEquidistant'],
                // 'geoGnomonic',
                ['geoOrthographic'],
                ['geoStereographic', d3.geoStereographic().rotate([-27, 0])],


                // Conic Projections
                ['geoConicConformal'],
                ['geoConicEqualArea'],
                ['geoConicEquidistant'],

                // Cylindrical Projections
                ['geoEquirectangular'],
                ['geoMercator'],
                ['geoTransverseMercator', d3.geoStereographic()],
                // Equal-Earth
                ['geoEqualEarth'],
                ['geoNaturalEarth1']
            ];

            function createLineString(start, end) {
                var dx = end[0] - start[0];
                var dy = end[1] - start[1];
                var segs = 100;
                var stepX = dx / segs;
                var stepY = dy / segs;
                var points = [];
                // TODO needs adaptive sampling on the -180 / 180 of azimuthal projections.
                for (let i = 0; i <= segs; i++) {
                    points.push([
                        start[0] + i * stepX,
                        start[1] + i * stepY
                    ]);
                }
                return points;
            }
            function normalizePoint(pt) {
                if (pt[0] === -180) {
                    pt[0] += 1e-2;
                }
                if (pt[0] === 180) {
                    pt[0] -= 1e-2;
                }
                if (pt[1] === -80) {
                    pt[1] += 1e-2;
                }
                if (pt[1] === 80) {
                    pt[1] -= 1e-2;
                }
                return pt;
            }
            // Add graticule
            var graticuleLineStrings = [];
            for (var lat = -80; lat <= 80; lat += 10) {
                graticuleLineStrings.push(
                    createLineString(normalizePoint([-180, lat]), normalizePoint([180, lat]))
                );
            }
            for (var lng = -180; lng <= 180; lng += 10) {
                graticuleLineStrings.push(
                    createLineString(normalizePoint([lng, -80]), normalizePoint([lng, 80]))
                );
            }

            worldJson.features.unshift({
                geometry: {
                    type: 'MultiLineString',
                    coordinates: graticuleLineStrings
                },
                properties: {
                    name: 'graticule'
                }
            });


            echarts.registerMap('world', worldJson);

            function createWorldOption(name, projection) {
                return {
                    series : [
                        {
                            type: 'map',
                            map: 'world',
                            roam: false,
                            itemStyle: {
                                borderColor: '#fff',
                                areaColor: '#000'
                            },
                            projection,
                            universalTransition: true,
                            animationDurationUpdate: 2000,
                            data:[
                                {
                                    name: 'graticule',
                                    itemStyle: {
                                        borderColor: '#ddd'
                                    },
                                    emphasis: {
                                        itemStyle: {
                                            borderColor: '#ddd'
                                        }
                                    }
                                }
                            ]
                        }
                    ]
                };
            }

            var chart = echarts.init(document.querySelector('#main'));

            var config = {
                projection: 'default'
            };

            function updateProjection(projectionName) {
                var projection = d3Projections.find(item => item[0] === projectionName)[1]
                    || d3[projectionName] && d3[projectionName]();
                var projectionOpt = projection && {
                    project: (pt) => {
                        return projection(pt)
                    },
                    unproject: (pt) => projection.invert(pt),
                    stream: projection.stream
                };
                var option = createWorldOption(projectionName, projectionOpt);
                if (projectionName === 'geoStereographic') {
                    // TODO
                    option.series[0].center = projection([0, 0]);
                    option.series[0].zoom = 30;
                }
                else if (projectionName === 'geoTransverseMercator') {
                    option.series[0].center = projection([0, 0]);
                    option.series[0].zoom = 4000;
                }
                else {
                    option.series[0].center = null,
                    option.series[0].zoom = 1;
                }
                option.title = {
                    text: projectionName,
                    left: 'center',
                    top: 0,
                    textStyle: {
                        fontSize: 14
                    }
                };
                chart.setOption(option);
            }

            updateProjection(config.projection);

            var gui = new dat.GUI();
            gui.add(config, 'projection',  d3Projections.map(item => item[0])).onChange(function () {
                updateProjection(config.projection);
            })
        });
        </script>


    </body>
</html>