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D3.js custom edge rendering

I am trying to make a graph which is sort of similar to a map. Here, I use a force-directed graph in which the nodes are locations and the edges are the paths between locations.
However, I can't seem to find any documentation on how to render an edge any different than a line with color attributes. (which I am doing now but looks kind of bland)
Is there some kind of way to have the edges custom rendered, for example, a repeated image of some sorts? Or even more specific, in my case for example, as a dirt path or similar?
Thanks in advance!

You can use <filter>:
<svg>
<filter id="my-filter">
<feFlood flood-color="orange" flood-opacity="0.75" in="SourceGraphic"></feFlood>
<feComposite operator="in" in2="SourceGraphic"></feComposite>
<feGaussianBlur stdDeviation="4"></feGaussianBlur>
<feComponentTransfer result="glow1">
<feFuncA type="linear" slope="4" intercept="0"></feFuncA>
</feComponentTransfer>
<feMerge>
<feMergeNode in="glow1"></feMergeNode><feMergeNode in="SourceGraphic"></feMergeNode>
</feMerge>
</filter>
<path d="M 10,10 L 100,100" filter="url(#my-filter)" stroke="orange" stroke-width="3"/>
</svg>

SVG make different sections of the path in different colors

I have been trying to implement the following requirements.
1. SVG path to have multiple colors on different sections (eg - red color the curves and rest of it, in black color)
2. Only allow mouse event- click on those colored areas (curves)
I have tried with plain javascript and snap.svg
Plain html & Javascript
[Codepen using HTML & Js][1]
SNAP.svg
[Codepen using SNAP.svg][2]
[1]: https://codepen.io/sanathko1234/pen/vvMQQZ
[2]: https://codepen.io/sanathko1234/pen/OrGoRa
How can this be achieved?

One solution would be to use the path twice: first the green one and next the one using stroke-dasharray. The dashes are only over the curves. If you don't like the position or the length of the dashes change them to what you need. The gaps are not sensitive to mouse events, only the dashes are.
In css I've added #gold:hover{cursor:pointer} so that you can see that only the dashes are sensitive to the mouse.
I hope it helps.
svg{border:1px solid}
use{fill:none;stroke-width:18;}
#gold:hover{cursor:pointer}
<svg viewBox="-10 50 580 360" width="580" height="360" xmlns="http://www.w3.org/2000/svg">
<defs>
<path id="svg_1" d="m555,272c1,0.76736 4,85.76736 -71,97.76736c-75,12 -387,-39 -388,-39.76736c0,-0.23264 -29,-1.23264 -45,-21.23264l-42,-124.76736c-3,-11.23264 -3,-21.23264 3,-26.23264c6,-5 46,-67 69,-69.76736l474,184z" />
</defs>
<g>
<title>background</title>
<rect fill="#fff" id="canvas_background" height="360" width="580" x="-10" y="50"/>
</g>
<g>
<title>Layer 1</title>
<use xlink:href="#svg_1" stroke="green" />
<use xlink:href="#svg_1" stroke="gold" stroke-dasharray ="130 370 110 60 90 40 90 400 52.45" id="gold" pointer-events="stroke" />
</g>
</svg>
Observation: the sum of the dashes and the gaps is 1342.45 which is also the total path length.

How would I add custom SVG shapes to an equation generated with MathJax?

I'd like to use MathJax to write various equations that include SVG shapes along the lines of the following:
(2 * [red box]) + [red box] = [three red boxes]
Where each item in brackets would be a custom SVG element defined in the HTML ranging from simple (a single box) to more complex (multiple shapes). The reason for needing this is that I want to use MathJax's ability to format math equations while replacing some symbols with SVG shapes. I may need to specify other HTML as well.
I suspect this can be achieved by using MathJax's HTML snippets but I don't know how to take the sample code they provide and make it work for any given equation.
Any help would be greatly appreciated.

If you are using MathML input, you can use the <mglyph> element to include an svg image into your expression, as in:
<math>
<mglyph src="dice.svg" height="42px" width="42px" valign="-14px" alt="Dice showing five dots"></mglyph>
</math>
or even
<math>
<mglyph src='data:image/svg+xml,
<svg xmlns="http://www.w3.org/2000/svg" height="42px" width="42px">
<rect stroke="black" fill="none" x="1px" y="1px" stroke-width="2px" rx="5px" width="40px" height="40px"></rect>
<circle stroke="black" fill="black" cy="30px" cx="30px" r="5px"></circle>
<circle stroke="black" fill="black" cy="30px" cx="10px" r="5px"></circle>
<circle stroke="black" fill="black" cy="20px" cx="20px" r="5px"></circle>
<circle stroke="black" fill="black" cy="10px" cx="30px" r="5px"></circle>
<circle stroke="black" fill="black" cy="10px" cx="10px" r="5px"></circle>
</svg>'
valign="-14px"
alt="Dice showing five dots">
</mglyph>
</math>
If you are using TeX input, you can create the mglyph using the \mmlToken macro:
\mmlToken{mglyph}[src="dice.svg" width="42px" height="42px" valign="-14px" alt="Dice showing five dots"]{}
You can also use the "img" extension from the third-party extension library. This defines an \img macro that makes loading the image a bit easier:
\img[-14px][42px][42px]{dice.svg}
I think you should be able to do what you want using one of those.
(This is my response to the cross-post on the MathJax User's Forum)

How to adjust contrast, darken/lighten vector graphics using dojox.gfx

I am using dojox.gfx to create and manipulate vector graphics. I need to adjust contrast and apply blur, darken/lighten effect on them?
And the browser I need to support are IE 8+. So, I have to achieve these things on SVG(IE 9) and VML(IE 8)
Is there a way to achieve this? Through dojo or any other library.

This is for svg:
<svg xmlns="http://www.w3.org/2000/svg" width="200" height="200">
<filter id="brightness">
<feComponentTransfer>
<feFuncR type="linear" slope="4"/>
<feFuncG type="linear" slope="4"/>
<feFuncB type="linear" slope="4"/>
</feComponentTransfer>
</filter>
<image filter="url(#brightness)" x="0" y="0" width="200" height="100" xlink:href="pic.png" />
</svg>
For VML I'm not sure.
It might be the blacklevel attribute,values are between -0.5(pure black) and 0.5(pure white)
<v:image style='width:200px;height:100px' src="images/temporary/pic2.png" blacklevel="-0.2"/>
This is the link for the vml blacklevel attribute
http://msdn.microsoft.com/en-us/library/bb229563%28v=vs.85%29.aspx

Is it possible to dynamically modify an SVG loaded as a resource with Javascript?

I have these icons and I'd like to procedurally add a drop shadow (basically, something, anything) to them on hover so they don't look so hokey.
They are SVG's so in theory I can prepend something like this:
<filter id="f1" x="0" y="0" width="200%" height="200%">
<feOffset result="offOut" in="SourceAlpha" dx="20" dy="20" />
<feGaussianBlur result="blurOut" in="offOut" stdDeviation="10" />
<feBlend in="SourceGraphic" in2="blurOut" mode="normal" />
</filter>
and some javascript magic to apply it on mouse over. This could possibly save ages of design work.
Problem is, the svg's are presented as <a style='background-image:url(icon.svg)' />.
Is there a way to get into the SVG element?

No, it's not directly possible. A workaround if you need this would be to use inline svg in html, or reference the svg files with either <object>, <iframe> or <embed>.
An example of using inline svg and a filter effect on hover here. The svg part looks like this essentially:
<svg width="400" height="400" viewBox="-2 -2 36 32">
<defs>
<style>
#stack polygon:hover { filter: url(#glow); }
</style>
<filter id="glow">
<feMorphology radius="0.7"/>
<feGaussianBlur stdDeviation="1"/>
<feColorMatrix type="matrix"
values="0 0 0 0 0
0 0 0 0.9 0
0 0 0 0.9 0
0 0 0 1 0"/>
</filter>
</defs>
<g id="stack" class="icon" fill="#850508">
<polygon points="0,20 16,24 32,20 32,24 16,28 0,24"/>
<polygon points="0,12 16,16 32,12 32,16 16,20 0,16"/>
<polygon points="0,4 16,0 32,4 32,8 16,12 0,8"/>
</g>
</svg>

If you're using SVG as an image then you can't get to the image's DOM and manipulate it via javascript.
While you could load them using XMLHTTPRequest and then insert them into the main document as inline data using the DOMParser object, this exposes you to the security issues that the browsers are trying to protect you from by locking down image access i.e. the image could change and you may be loading arbitrary javascript into your page.
What would seem simplest and safest to me is if you just alter the image files directly using an editor and add the filter into them then use the modified images.

What if you use jquery addclass and simply link to another svg that has your changes?
You can also create an svg element with html code (right click on file --> view with notepad) and you will have the code there -- there are online converters that can make all neccessary tweaks and then you can enter the svg code with javascript

I don't know how to do it in the way you show... as a background image... but if you can load the svg file inside a div as in this example you can you can use my importer (a modified version of others importers founded on github) that it's here: http://www.dariomac.com/Document/Raphael-Utils. You can also see this storify where I describe all the steps followed by me to import SVG directly from file.