使用two.js生成的卫星环绕动画效果

来源：GBin1.com



two.js是一个帮助你实现绘图和动画效果的类库，同时支持三种前端绘图实现：

webgl

svg

2d画布

使用这个类库，可以方便的支持这三种不同的实现，你只需要设置参数：Two.Types.canvas, Two.Types.svg, or Two.Types.webgl

下面是使用two.js生成的一个动画效果：

http://www.gbtags.com/gb/debug/592abb4d-6449-4654-a824-0232c0c3b110.htm

相关JS代码如下：

var el = document.getElementById("main"),
two = new Two({
width: '800',
height: '600'
});
two.appendTo(el);

var earthAngle = 0,
moonAngle = 0,
distance = 30,
radius = 50,
padding = 100,
orbit = 200,
offset = orbit + padding,
orbits = two.makeGroup();

var earthOrbit = two.makeCircle(offset, offset, orbit);
earthOrbit.noFill();
earthOrbit.linewidth = 2;
earthOrbit.stroke = "#EFEFEF";
orbits.add(earthOrbit);
two.update();

var pos = getPositions(earthAngle++, orbit),
earth = two.makeCircle(pos.x + offset, pos.y + offset, radius);
earth.stroke = "#444";
earth.linewidth = 3;
earth.fill = "#CCCCCC";

var moonOrbit = two.makeCircle(earth.translation.x, earth.translation.y, radius + distance);
moonOrbit.noFill();
moonOrbit.linewidth = 2;
moonOrbit.stroke = "#ccc";
orbits.add(moonOrbit);
var pos = getPositions(moonAngle, radius + distance),
moon = two.makeCircle(earth.translation.x + pos.x, earth.translation.y + pos.y, radius / 4);
moonAngle += 5;
moon.fill = "#474747";

two.bind("update", function (frameCount) {
var pos = getPositions(earthAngle++, orbit);
earth.translation.x = pos.x + offset;
earth.translation.y = pos.y + offset;

var moonPos = getPositions(moonAngle, radius + distance);
moon.translation.x = earth.translation.x + moonPos.x;
moon.translation.y = earth.translation.y + moonPos.y;
moonAngle += 5;
moonOrbit.translation.x = earth.translation.x;
moonOrbit.translation.y = earth.translation.y;
});

function getPositions(angle, orbit) {
return {
x: Math.cos(angle * Math.PI / 180) * orbit,
y: Math.sin(angle * Math.PI / 180) * orbit
};
}
two.play();

网站地址：http://jonobr1.github.io/two.js

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来源：使用two.js生成的卫星环绕动画效果