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# Vector Graph

⚠️ This library is experimental until 1.0.0 in npm. For updates follow me!

Generate high-quality geometry and vector graphs with HTML:   Basic building blocks Geometry and angles Crank it up a notch
<vector-graph id="basics" units>
<line label="line" from="1,8" to="6,5"></line>
<point label="point" x="7" y="7"></point>
<vector label="vector" to="8,4" axis></vector>
</vector-graph>

<vector-graph id="triangle" x="3" y="3" axis="false">
<polygon points="0,0;1,3;3,1" sides="a,b,c" angles="α,β,γ"></polygon>
</vector-graph>

<vector-graph id="complete" x="4.9" y="4.9">
<vector label="b" color="blue" from="3,4" to="4,2" axis></vector>
<vector label="a" color="red" from="0,0" to="3,4" axis></vector>
<vector label="c" from="0,0" to="4,2"></vector>
</vector-graph>


Note: none of the ids are necessary, but we add them because it's nice

## Getting started

To use this library as usual you'll need three things. First, import it from a CDN; put this line anywhere in your HTML:

<script src="https://cdn.jsdelivr.net/npm/vector-graph"></script>


Now let's draw a graph anywhere within your HTML: <vector-graph grid id="plain">
<vector label="u" to="8,4"></vector>
<vector label="v" to="4,8"></vector>
</vector-graph>


## Documentation

The way you build images is with a parent <vector-graph> that draws the image and few top-level configuration (like the axis, grid, etc) and then add elements inside.

Unless specified otherwise all units should be local units. So for example, the default plane axis sizes are defined as x=[0,10] and y=[0,10]. This means that if you want to put a point in 2,2, then you'd use those coordinates, never pixel values: <vector-graph id="basic-units">
<point x="2" y="2" label="2,2"></point>
</vector-graph>


The same applies to positioning of all other elements. There are some exceptions, like the width and height of <vector-graph>, or the width for the <line width="3"> which is also in pixels.

### <vector-graph>

Create a vector graph image. It controls the display of grids, axis, numbers, etc.

attribute default description
width 200 The width of the containing SVG element (pixels)
height 200 The height of the containing SVG element (pixels)
x 0,10 The x-coordinates of the graph to fit into the SVG
y 0,10 The y-coordinates of the graph to fit into the SVG
units false Show the numbers on each of the axis
grid 1 The size of the grid, or false to hide it
axis x,y The X and Y axis labels, or false to hide the axis
dark auto Dark theme (true), light theme (false) or auto (undef)
pad 30 The space around the content to avoid SVG clipping

Control the grid size and position with x, y and grid:   Default grid 10x10 Shifted and scaled No grid at all
<vector-graph id="default-grid" units>
<point label="0,0" x="0" y="0"></point>
</vector-graph>

<vector-graph id="shifted-grid" x="-0.3,3" y="-0.3,3" units>
<point label="0,0" x="0" y="0"></point>
</vector-graph>

<vector-graph id="center-grid" x="-2.8,2.8" y="-2.8,2.8" units>
<point label="0,0" x="0" y="0"></point>
</vector-graph>


You can also hide the different parts of the grid; let's change the size, remove the units and disable the axis and grid:   1x1 grid of 0.2 steps Hide the grid Hide grid and axis
<vector-graph id="small-grid" x="0,1" y="0,1" grid="0.2" units>
<point label="0,0" x="0" y="0"></point>
</vector-graph>

<vector-graph id="no-grid" grid="false">
<point label="0,0" x="0" y="0"></point>
</vector-graph>

<vector-graph id="no-axis" grid="false" axis="false">
<point label="0,0" x="0" y="0"></point>
</vector-graph>


### <point>

Draws a small circle in the graph that represents a point in space: <vector-graph id="point">
<point label="a"></point>
<point x="2" y="1"></point>
<point x="4" y="2" label="c" color="blue"></point>
<point x="6" y="5" label="d" axis></point>
<point x="8" y="8" label="e" color="red" axis></point>
</vector-graph>

attribute default description
x 0 The horizontal coordinate where to draw the point
y 0 The vertical coordinate where to draw the point
label none The text to draw on top of the point
color black The color of the point, it can be a name or hexa
axis false Draw the horizontal and vertical coordinate lines

### <line>

Draws a segment between two given points: <vector-graph id="line">
<line label="a" to="6,6"></line>
<line label="b" from="2,8" to="8,8"></line>
<line label="c" from="6,1" to="6,5" color="red" width="1"></line>
<line label="d" from="8,1" to="8,7" color="blue" width="3" dashed></line>
</vector-graph>

attribute default description
to none The point where the line/segment ends
from 0,0 The point where the line/segment starts
label none Text to draw on the middle of the line
color black The color of the line, it can be a name or hexa
width 1.75 The stroke width of the line to draw
dashed false Show as dashes (true) or as a solid line (false)

### <circle>

Draw a hollow circle around the specified center: <vector-graph id="circle" x="-1,6" y="-1,6">
<circle label="a"></circle>
<circle label="c" x="2" y="5" color="red"></circle>
<circle label="d" x="5" y="2" width="1"></circle>
<circle label="e" x="5" y="5" color="blue" width="3"></circle>
</vector-graph>

attribute default description
x 0 The horizontal coordinate of the circle's center
y 0 The vertical coordinate of the circle's center
radius 1 The circle's radius, in coordinates size
label none Text to draw on the middle of the line
color black The color of the line, it can be a name or hexa
width 1.75 The stroke width of the line to draw

### <vector>

attribute default description
to none The point where the vector ends with an arrow
from 0,0 The point where the vector starts
label none Text to draw on the middle of the line
color black The color of the line, it can be a name or hexa
axis false Draw the horizontal and vertical coordinate lines

### <polygon>   Simple polygon Different shapes With angles and sides
<vector-graph id="regular-polygon">
<polygon points="2,2;6,2;6,6;2,6"></polygon>
</vector-graph>

<vector-graph id="complex-polygons" axis="false" x="6" y="6">
<polygon points="1,1;6,0;2,2;4,4;0,6" color="red"></polygon>
</vector-graph>

<vector-graph id="angles-polygon" axis="false">
<polygon points="1,1;7,1;9,9;1,7" sides="a,b,c,d" angles="α,β,γ,δ"></polygon>
</vector-graph>

attribute default description
points none All of the points of the domain
color black The color of the line, it can be a name or hexa
angles false Draw the angles in the internal vertices

### <angle>

Draws an arc representing the angle between two existing lines (the lines must be drawn separately). <vector-graph id="angle">
<angle label="b" from="45" to="90" radius="5" color="red"></angle>
<angle label="c" to="45" radius="5" color="blue" dashed="false"></angle>
<angle label="d" x="7" radius="2" from="0" to="180"></angle>
</vector-graph>

attribute default description
x 0 The horizontal coordinate of the angle's center
y 0 The vertical coordinate of the angle's center
from 0 The angle (in degrees) to start drawing the arc
to none The angle (in degrees) to finish drawing the arc
radius 1 The angle's arc radius, in coordinates size
label none Text to draw on the middle of the line
color black The color of the line, it can be a name or hexa
size normal The label's size
dashed true Draw dashes instead of a solid line

### <text>

attribute default description
text none The content that goes inside the label
x none The horizontal coordinate where to draw the label
y none The vertical coordinate where to draw the label
color black Color of text and border, it can be a name or hexa
size normal Define how big it is: "tiny, small, normal or large"
width auto The width of the label, leave it empty

### <label>

attribute default description
text none The content that goes inside the label
x none The horizontal coordinate where to draw the label
y none The vertical coordinate where to draw the label
color black Color of text and border, it can be a name or hexa
size normal Define how big it is: "tiny, small, normal or large"
width auto The width of the label, tip: leave it empty
height auto The height of the label, tip: leave it empty

### <plot> attribute default description
fn string The function to draw (in Javascript)
color black Color of plotted line, it can be a name or hexa
width auto The width of the line to draw
<vector-graph id="custom-function" x="-5,5" y="-2,2">
<plot fn="Math.tan(x)" color="red" width="1"></plot>
<plot fn="Math.sin(x)" color="green"></plot>
<plot fn="Math.cos(x)" color="blue"></plot>
</vector-graph>


## Examples <vector-graph id="imaginary">
<vector to="6,6" axis="a,b"></vector>
<point label="a+bi" x="6" y="6" color="red"></point>
</vector-graph>


### Custom function <vector-graph id="custom-function" x="-5,5" y="-2, 2">
<plot fn="Math.tan(x)" color="red" width="1"></plot>
<plot fn="Math.sin(x)" color="green"></plot>
<plot fn="Math.cos(x)" color="blue"></plot>
</vector-graph>


### Full XY Plane <vector-graph width="400" height="400" x="-5,5" y="-5,5" id="electromagnetism">
<point x="0" y="0"></point>

<text text="Electric Field" x="-2.7" y="2.4" color="red"></text>
<label text="Right Hand Rule" x="2.5" y="-4"></label>

<vector color="red" from="-0.5,-1" to="0.5,-1"></vector>
<vector color="red" from="0.5,1" to="-0.5,1"></vector>
<vector color="red" from="1,-0.5" to="1,0.5"></vector>
<vector color="red" from="-1,0.5" to="-1,-0.5"></vector>

<vector color="red" from="-1,-2" to="1,-2"></vector>
<vector color="red" from="1,2" to="-1,2"></vector>
<vector color="red" from="2,-1" to="2,1"></vector>
<vector color="red" from="-2,1" to="-2,-1"></vector>

<vector color="red" from="-1.5,-3" to="1.5,-3"></vector>
<vector color="red" from="1.5,3" to="-1.5,3"></vector>
<vector color="red" from="3,-1.5" to="3,1.5"></vector>
<vector color="red" from="-3,1.5" to="-3,-1.5"></vector>
</vector-graph>


## Environments

### Javascript

Follow the Getting Started guide and it'll all work great. You can include the script at the beginning or at the end of your HTML, it doesn't matter.

### Node.js

You can run this on the Node.js side to generate static SVGs as well. To do so, you'll need to install jsdom on your own and then use it like this:

import { JSDOM } from "jsdom";
import graph from "vector-graph";

// Make some of these variable accessible from anywhere
const dom = new JSDOM();
global.window = dom.window;
global.document = window.document;
global.DOMParser = window.DOMParser;

// Render the HTML to SVG
const svg = graph(
<vector-graph>
<point label="point" x="7" y="7"></point>
<line label="line" from="0,0" to="4,8"></line>
<vector label="vector" to="8,4"></vector>
</vector-graph>
);

console.log(svg);
// <svg width="200" height="200" viewBox="...">...</svg>


I love Katex and I've written several tutorials in the past about mathematics, but I've felt that we are lacking on a way of describing mathematic vectors and equations easily on the web.

There is one project that does a similar thing, but it's way too large (680kb of JS!) and overly complex in my opinion. Instead, I just wanted a way of easily define a simple graph with plain HTML, something like this: <vector-graph id="about">
<vector to="6,8"></vector>
</vector-graph>


So after some experimenting and seeing it was possible, I decided to create this library. I'm using SVG since it is scalable and its API is not terrible to work with. It's also not awesome to work with, hence a non-trivial part of the library internals are dedicated to work around some SVG issues.

Now, I've spent a lot of hours creating this and I'm releasing it for everyone to use for free. My ask is that if you want to use my work, you either also release your work for others to use, or compensate me so I can keep building amazing things!