220Echarts - 3D 地球（Animating Contour on Globe）

var config = {
    color: '#c0101a',
    levels: 1,
    intensity: 4,
    threshold: 0.01
}
var canvas = document.createElement('canvas');
canvas.width = 4096;
canvas.height = 2048;
context = canvas.getContext("2d");
context.lineWidth = 0.5;
context.strokeStyle = config.color;
context.fillStyle = config.color;
context.shadowColor = config.color;
$.when(
    $.getScript('./vendors/d3/d3-contour.js'),
    $.getScript('./vendors/d3/d3-geo.js'),
    $.getScript('./vendors/d3/d3-timer.js')
).done(function () {
    image('data-gl/asset/bathymetry_bw_composite_4k.jpg').then(function(image) {
        var m = image.height,
            n = image.width,
            values = new Array(n * m),
            contours = d3.contours().size([n, m]).smooth(true),
            projection = d3.geoIdentity().scale(canvas.width / n),
            path = d3.geoPath(projection, context);
        //   StackBlur.R(image, 5);
        for (var j = 0, k = 0; j < m; ++j) {
            for (var i = 0; i < n; ++i, ++k) {
            values[k] = image.data[(k << 2)] / 255;
            }
        }
        var opt = {
            image: canvas
        }
        var results = [];
        function update(threshold, levels) {
            context.clearRect(0, 0, canvas.width, canvas.height);
            var thresholds = [];
            for (var i = 0; i < levels; i++) {
                thresholds.push((threshold + 1 / levels * i) % 1);
            }
            results = contours.thresholds(thresholds)(values);
            redraw();
        }
        function redraw() {
            results.forEach(function (d, idx) {
                context.beginPath();
                path(d);
                context.globalAlpha = 1;
                context.stroke();
                if (idx > config.levels / 5 * 3) {
                    context.globalAlpha = 0.01;
                    context.fill();
                }
            });
            opt.onupdate();
        }
        d3.timer(function(t) {
            var threshold = (t % 10000) / 10000;
            update(threshold, 1);
        });
        initCharts(opt);
        update(config.threshold, config.levels);
    });
    function image(url) {
        return new Promise(function(resolve) {
            var image = new Image();
            image.src = url;
            image.onload = function() {
            var canvas = document.createElement("canvas");
            canvas.width = image.width / 8;
            canvas.height = image.height / 8;
            var context = canvas.getContext("2d");
            context.drawImage(image, 0, 0, canvas.width, canvas.height);
            resolve(context.getImageData(0, 0, canvas.width, canvas.height));
            };
        });
    }
    function initCharts(opt) {
        var contourChart = echarts.init(document.createElement('canvas'), null, {
            width: 4096,
            height: 2048
        });
        var img = new echarts.graphic.Image({
            style: {
                image: opt.image,
                x: -1,
                y: -1,
                width: opt.image.width + 2,
                height: opt.image.height + 2
            }
        });
        contourChart.getZr().add(img);
        opt.onupdate = function () {
            img.dirty();
        };
        myChart.setOption({
            backgroundColor: '#000',
            globe: {
                environment: 'data-gl/asset/starfield.jpg',
                heightTexture: 'data-gl/asset/bathymetry_bw_composite_4k.jpg',
                displacementScale: 0.05,
                displacementQuality: 'high',
                baseColor: '#000',
                shading: 'realistic',
                realisticMaterial: {
                    roughness: 0.2,
                    metalness: 0
                },
                postEffect: {
                    enable: true,
                    depthOfField: {
                        // enable: true
                    }
                },
                light: {
                    ambient: {
                        intensity: 0
                    },
                    main: {
                        intensity: 0.1,
                        shadow: false
                    },
                    ambientCubemap: {
                        texture: 'data-gl/asset/lake.hdr',
                        exposure: 1,
                        diffuseIntensity: 0.5,
                        specularIntensity: 2
                    }
                },
                viewControl: {
                    autoRotate: false
                },
                layers: [{
                    type: 'blend',
                    blendTo: 'emission',
                    texture: contourChart,
                    intensity: config.intensity
                }]
            }
        });
    }
});