我发现svg过滤器元素与路径元素一起使用时会出现问题。当路径元素有像这个d="M28,46L28,23L77,23"这样的指令来渲染两条正交线时，它可以正常工作，滤镜和阴影渲染按预期方式，但随着其中一条线的长度接近零，出现了一个问题：路径元素（包括任何标记）开始被过滤器剪切
我不明白究竟发生了什么，但似乎过滤器的边界框（路径边界框的百分比）会折叠到零高度，这会以某种方式剪切引用路径元素。一旦路径边界框变为零，问题就会消失（至少在Chrome和Opera中会消失...）。
我找不到任何关于此的错误报告，有人能解释这种行为和/或建议一种处理它的方法吗？
var width = 300,
height = 100,
constant = 10;
var svg = d3.select('body').append('svg')
.attr('width', width)
.attr('height', height);
var defs = svg.append("defs");
var markerW = 8,
markerH = 6,
marker = defs.append('marker')
.attr('id', "triangle")
.attr('viewBox', "0 0 10 10")
.attr('refX', "0")
.attr('refY', 5)
.attr('markerUnits', 'strokeWidth')
.attr('markerWidth', markerW)
.attr('markerHeight', markerH)
.attr('orient', 'auto')
var path = marker.append('path')
.attr('d', "M 0 0 L 10 5 L 0 10 z")
// create filter with id #drop-shadow
// height=130% so that the shadow is not clipped
var filter = defs.append("filter")
.attr("id", "drop-shadow")
.attr({
"height": "200%",
"width": "200%",
x: "-50%",
y: "-50%"
})
/*.style({opacity: 0.5})*/
;
// SourceAlpha refers to opacity of graphic that this filter will be applied to
// convolve that with a Gaussian with standard deviation 3 and store result
// in blur
filter.append("feGaussianBlur")
.attr("in", "SourceAlpha")
.attr("stdDeviation", 1)
.attr("result", "blur");
// translate output of Gaussian blur to the right and downwards with 2px
// store result in offsetBlur
var feOffset = filter.append("feOffset")
.attr("in", "blur")
.attr("dx", 2)
.attr("dy", 2)
.attr("result", "offsetBlur");
// overlay original SourceGraphic over translated blurred opacity by using
// feMerge filter. Order of specifying inputs is important!
var feMerge = filter.append("feMerge");
feMerge.append("feMergeNode")
.attr("in", "offsetBlur")
feMerge.append("feMergeNode")
.attr("in", "SourceGraphic");
var connector = d3.svg.line().interpolate("linear")
.x(function(d) {
return Math.round(d[0])
})
.y(function(d) {
return Math.round(d[1])
});
function linkPath(d) {
var x1 = d[0][0],
y1 = d[0][1],
x2 = d[1][0],
y2 = d[1][1];
return connector([
[x1, y1],
[x1, y2],
[x2, y2]
]);
}
var link = svg.selectAll('.link')
.data([
[
[10, 40],
[200, 40]
]
])
.enter()
.append('path').attr("class", "link")
.attr("stroke-width", "2")
.attr('marker-end', 'url(#triangle)')
.attr('stroke', 'black')
.attr("fill", "none")
.style("filter", "url(#drop-shadow)")
.attr("d", linkPath)
function start() {
var t = 3000;
link.data([
[
[10, 60],
[200, 40]
]
])
.transition().delay(t / 3).duration(t).ease("linear")
.attr("d", linkPath)
.each("end", function() {
link.data([
[
[10, 40],
[200, 40]
]
])
.transition().duration(t).ease("linear")
.attr("d", linkPath)
.each("end", function() {
link.data([
[
[10, 20],
[200, 40]
]
])
.transition().delay(t / 3).duration(t).ease("linear")
.attr("d", linkPath)
.each("end", function() {
link.data([
[
[10, 40],
[200, 40]
]
])
.transition().duration(t).ease("linear")
.attr("d", linkPath)
.each("end", start)
})
})
})
};
start();<script src="https://cdnjs.cloudflare.com/ajax/libs/d3/3.4.11/d3.min.js"></script>
答案 0 :(得分：1)
在调整过滤器区域大小时，不同浏览器的行为会有所不同。它们中的一些忽略了笔划宽度 - 因此当您获得水平或垂直线时，过滤器区域会折叠为零。您可以通过在userSpace单元中指定过滤器区域，或者将过滤器放在具有显式尺寸的包装g元素上来修复它。
答案 1 :(得分：1)
The Filter Effects Region中的特定文本，该文本使用x，{{1 }}，y和width属性描述了过滤器适用的区域。
如果按百分比定义它，它会随着路径边界框的缩小而缩小。即使您使用较大的百分比，它也会在边界框中折叠为零。这就是你剪裁的原因。
好消息是你不必使用百分比。只需在适当的坐标中指定过滤区域即可。
height var width = 300,
height = 100,
constant = 10;
var svg = d3.select('body').append('svg')
.attr('width', width)
.attr('height', height);
var defs = svg.append("defs");
var markerW = 8,
markerH = 6,
marker = defs.append('marker')
.attr('id', "triangle")
.attr('viewBox', "0 0 10 10")
.attr('refX', "0")
.attr('refY', 5)
.attr('markerUnits', 'strokeWidth')
.attr('markerWidth', markerW)
.attr('markerHeight', markerH)
.attr('orient', 'auto')
var path = marker.append('path')
.attr('d', "M 0 0 L 10 5 L 0 10 z")
// create filter with id #drop-shadow
// height=100 pixels so that the shadow is not clipped
var filter = defs.append("filter")
.attr("id", "drop-shadow")
.attr("filterUnits", "userSpaceOnUse")
.attr({
"height": "100",
"width": "300",
x: "-50",
y: "-50"
})
/*.style({opacity: 0.5})*/
;
// SourceAlpha refers to opacity of graphic that this filter will be applied to
// convolve that with a Gaussian with standard deviation 3 and store result
// in blur
filter.append("feGaussianBlur")
.attr("in", "SourceAlpha")
.attr("stdDeviation", 1)
.attr("result", "blur");
// translate output of Gaussian blur to the right and downwards with 2px
// store result in offsetBlur
var feOffset = filter.append("feOffset")
.attr("in", "blur")
.attr("dx", 2)
.attr("dy", 2)
.attr("result", "offsetBlur");
// overlay original SourceGraphic over translated blurred opacity by using
// feMerge filter. Order of specifying inputs is important!
var feMerge = filter.append("feMerge");
feMerge.append("feMergeNode")
.attr("in", "offsetBlur")
feMerge.append("feMergeNode")
.attr("in", "SourceGraphic");
var connector = d3.svg.line().interpolate("linear")
.x(function(d) {
return Math.round(d[0])
})
.y(function(d) {
return Math.round(d[1])
});
function linkPath(d) {
var x1 = d[0][0],
y1 = d[0][1],
x2 = d[1][0],
y2 = d[1][1];
return connector([
[x1, y1],
[x1, y2],
[x2, y2]
]);
}
var link = svg.selectAll('.link')
.data([
[
[10, 40],
[200, 40]
]
])
.enter()
.append('path').attr("class", "link")
.attr("stroke-width", "2")
.attr('marker-end', 'url(#triangle)')
.attr('stroke', 'black')
.attr("fill", "none")
.style("filter", "url(#drop-shadow)")
.attr("d", linkPath)
function start() {
var t = 3000;
link.data([
[
[10, 60],
[200, 40]
]
])
.transition().delay(t / 3).duration(t).ease("linear")
.attr("d", linkPath)
.each("end", function() {
link.data([
[
[10, 40],
[200, 40]
]
])
.transition().duration(t).ease("linear")
.attr("d", linkPath)
.each("end", function() {
link.data([
[
[10, 20],
[200, 40]
]
])
.transition().delay(t / 3).duration(t).ease("linear")
.attr("d", linkPath)
.each("end", function() {
link.data([
[
[10, 40],
[200, 40]
]
])
.transition().duration(t).ease("linear")
.attr("d", linkPath)
.each("end", start)
})
})
})
};
start();