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在 Paperjs 网站上，此页面上有一个移动多个项目的示例http://paperjs.org/tutorials/animation/creating-animations/移动的项目是从左到右连续移动的浮动圆圈。我正在尝试修改此示例以使圆圈连续从底部浮动到顶部。到目前为止，我已经设法让它们从底部漂浮到顶部，但由于某种原因，它不是连续的。

我试图对示例进行的另一个修改是让圆圈具有基于给定颜色数组的随机颜色。到目前为止，仅在每次刷新和加载页面时都会生成随机颜色。

  1. 我怎样才能让圆圈从底部到顶部连续浮动？

  2. 如何让圆圈在动画中随机着色，而不仅仅是在页面加载时？

这是我的修改代码：

// The amount of circles we want to make:
    var count = 50;

    /*random colors for circles*/
    var circleColors = new Array();
    circleColors[0] = "#2ab4e4";//BLUE
    circleColors[1] = "#a2a7a6";//GREY
    circleColors[2] = "#ef7047";//ORANGE
    circleColors[3] = "#ffffff";//WHITE
    /*end random colors for circles*/

    // Create a symbol, which we will use to place instances of later:
    var path = new Path.Circle({
        center: [0, 0],
        radius: 35,
        fillColor: circleColors[Math.floor(Math.random() * circleColors.length)]
    });

    var symbol = new Symbol(path);

    // Place the instances of the symbol:
    for (var i = 0; i < count; i++) {
        // The center position is a random point in the view:
        var center = Point.random() * view.size;
        var placedSymbol = symbol.place(center);
        placedSymbol.scale(i / count);
    }

    // The onFrame function is called up to 60 times a second:
    function onFrame(event) {
        // Run through the active layer's children list and change
        // the position of the placed symbols:
        for (var i = 0; i < count; i++) {
            var item = project.activeLayer.children[i];

            // Move the item 1/20th of its width to the right. This way
            // larger circles move faster than smaller circles:
            item.position.y -= item.bounds.height / 20;

            // If the item has left the view on the right, move it back
            // to the left:
            if (item.bounds.bottom > view.size.height) {
                item.position.y = -item.bounds.height;
            }
        }
    }

这是 Paperjs 的原始代码：

// The amount of circles we want to make:
    var count = 150;

// Create a symbol, which we will use to place instances of later:
    var path = new Path.Circle({
    center: [0, 0],
    radius: 10,
    fillColor: 'white',
    strokeColor: 'black'
    });

    var symbol = new Symbol(path);

// Place the instances of the symbol:
    for (var i = 0; i < count; i++) {
    // The center position is a random point in the view:
    var center = Point.random() * view.size;
    var placedSymbol = symbol.place(center);
    placedSymbol.scale(i / count);
    }

// The onFrame function is called up to 60 times a second:
    function onFrame(event) {
    // Run through the active layer's children list and change
    // the position of the placed symbols:
    for (var i = 0; i < count; i++) {
    var item = project.activeLayer.children[i];

    // Move the item 1/20th of its width to the right. This way
    // larger circles move faster than smaller circles:
    item.position.x += item.bounds.width / 20;

    // If the item has left the view on the right, move it back
    // to the left:
    if (item.bounds.left > view.size.width) {
        item.position.x = -item.bounds.width;
    }
    }
    }
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1 回答 1

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paper.js 坐标系的原点位于画布的左上角。要将项目置于视口边界之下，您需要将视图的高度添加到项目的高度。

if (item.bounds.bottom < 0) {
            item.position.y = view.size.height+item.bounds.height;
        }

至于随机颜色，您必须使用 pathItems，而不是放置符号来改变对象的颜色样式。而不是这个：

var path = new Path.Circle({
    center: [0, 0],
    radius: 35,
    fillColor: circleColors[Math.floor(Math.random() * circleColors.length)]
});

var symbol = new Symbol(path);

// Place the instances of the symbol:
for (var i = 0; i < count; i++) {
    // The center position is a random point in the view:
    var center = Point.random() * view.size;
    var placedSymbol = symbol.place(center);
    placedSymbol.scale(i / count);
}

你需要更多类似的东西：

// Place the instances of the symbol:
for (var i = 0; i < count; i++) {
    var path = new Path.Circle({
    center: Point.random() * view.size,
    radius: i / count,
    fillColor: circleColors[Math.floor(Math.random() * circleColors.length)]
});

有关详细信息，请参阅此帖子： Swarm 中的所有路径都需要具有相同的填充颜色吗？

于 2013-07-23T17:30:40.003 回答