GFXFundamentals Lesson Builder

This is the lesson builder (static site generator) used on WebGLFundamentals, WebGL2Fundamentals, and ThreeJSFundamentals.

The code is a mess as it started small and got hacked over time.

Still, I got tired of propagating changes between projects so I managed to get it separated out.

I'm not sure it has any features over something like Jekyll except

it's written in JavaScript.

I'm not saying Ruby is bad. Only that I really only want to have to maintain one dev environment.

I particularly like that npm defaults to all dependencies being local. No knowledge needed. No special incantations. It just works. My, very limited experience with Ruby is that Ruby expects many things to be globally installed and you have to use other tools to help you make things local.
I think, but I'm probably wrong, that it handles HTML better.

My markdown files have lots of embedded HTML. For whatever reason most of time I try this in other systems they get confused and end up seeing markdown inside portions of HTML. I probably just don't know how to use them correctly.
It handles multiple languages

I'm sure other systems do that too but it's not a common request so I'm guessing that's often less supported.

Anyway, I'm not trying to promote this as a solution to anything. It's just what I have hacked together over the years to make the sites listed above.

Docs

These are in no way complete. They're most notes to myself.

.md files

.md files have front matter like headers at the front. Basically a keyword followed by a colon. and a space. A blank line ends the front matter and starts the content

Title: The title for the page
TOC: (optional) The title for the table of contents if different
Description: A description currently only used for meta data like for facebook/twitter
Link: (optional) A link to some other page

The link's sole purpose is to put an external link in the table of contents. It also lets the title of that link be localized (the link can be localized too) as in

some-article.md
```
Title: How to use Canvas
Link: https://developer.mozilla.org/en-US/docs/Web/API/Canvas_API
```
ja/some-article.md
```
Title: Canvasの使い方
Link: https://developer.mozilla.org/ja/docs/Web/API/Canvas_API
```

English lessons sit in .md files in a folder called lessons below a folder named whatever, usually the topic of the site. Example webgl/lessons/some-lesson.md. Translations have .md files of the same name one subfolder deeper, ideally using the language code. Example webgl/lessons/zh_cn/some-lesson.md.

required files

contributors.md
toc.hanson
build/templates/index.template
build/templates/lessons.template
build/templates/missing.template
build/templates/example.template
build/templates/diagram.template
<topic>/lessons/index.md
<topic>/lessons/toc.html
<topic>/lessons/langinfo.hanson
<topic>/lessons/at-least-one-lesson.md

langinfo.hanson

Each language folder as well as the English folder have a langinfo.hanson file which is similar to JSON except comments and trailing commas are allowed.

The contents is

{
  // The language (will show up in the language selection menu)
  language: 'English',

  // only needed if different from the folder name
  langCode: 'en',

  // Phrase that appears under examples
  defaultExampleCaption: "click here to open in a separate window",

  // Title that appears on each page
  title: 'WebGL Fundamentals',

  // Basic description that appears on each page
  description: 'Learn WebGL from the ground up. No magic',

  // Link to the language root.
  link: 'https://webglfundamentals.org/webgl/lessons/ja',  // replace `ja` with country code

  // html that appears after the article and before the comments
  commentSectionHeader: '<div>Questions? <a href="https://stackoverflow.com/questions/tagged/webgl">Ask on stackoverflow</a>.</div>\n        <div>Issue/Bug? <a href="https://github.com/gfxfundamentals/webgl-fundamentals/issues">Create an issue on github</a>.</div>',

  // markdown that appears for untranslated articles
  missing: "Sorry this article has not been translated yet. [Translations Welcome](https://github.com/gfxfundamentals/webgl-fundamentals)! 😄\n\n[Here's the original English article for now]({{{origLink}}}).",

  // various translations
  translations: {
    badTranslation: 'Sorry, the translation of this area is out of date. <a href="{{packageJSON.homepage}}/blob/master/{{contentFileName}}">Please consider helping to fix it</a>.',
    updateNeeded: 'The translation of this article is out of date.  <a href="{{packageJSON.homepage}}/blob/master/{{contentFileName}}">Please consider helping to fix it</a>.',
  },

  // the phrase "Table of Contents"
  toc: "Table of Contents",

  // translation of categories for table of contents
  categoryMapping: {
    'fundamentals': "Fundamentals",
    'image-processing': "Image Processing",
    'matrices': "2D translation, rotation, scale, matrix math",
    '3d': "3D",
    'lighting': "Lighting",
    'organization': "Structure and Organization",
    'geometry': "Geometry",
    'textures': "Textures",
    'rendertargets': "Rendering To A Texture",
    '2d': "2D",
    'text': "Text",
    'misc': "Misc",
    'reference': "Reference",
  },

}

toc.hanson

This is the table of contents. It looks like this

{
  "topic1": [
    "some-article.md",
    "some-other-article.md",
  ],
  "topic2": [
    "another-article.md",
    "yet-another-article.md",
  ],
  "topic3": [
    "sub-topic1": [
      "foo-article.md",
      "bar-article.md",
    ],
  ]
}

The actual HTML generated is a nested <ul> list where topic1 is translated via the langInfo.json and the titles come from the articles/lessons.

toc.html

This is a language specific template the table of contents. allowing you to add links that are language specific. Example:

{{{tocHtml}}}
<ul>
  <li><a href="/docs/">Helper API Docs</a></li>
  <li><a href="https://twgljs.org">TWGL, A tiny WebGL helper library</a></li>
  <li><a href="https://github.com/gfxfundamentals/webgl-fundamentals">github</a></li>
</ul>

Yes: this should be renamed to toc.template 😅

index.md

This is the language specific content of index.html for each language that gets inserted as content into the index.template.

Example:

Title: WebGL Fundamentals

WebGL from the ground up. No magic.

These are a set of articles that teach WebGL from basic principles.
They are NOT old rehashed out of date OpenGL articles like many others on the net.
They are entirely new, discarding the old out of date ideas and bringing you
to a full understanding of what WebGL really is and how it really works.

{{{include "webgl/lessons/toc.html"}}}

Building

const buildStuff = require('@gfxfundamentals/lesson-builder');
async function main() {}
  const buildSettings = {
    outDir: 'out',  // where to generate the site
    baseUrl: 'https://webglfundamentals.org',  // the site
    rootFolder: 'webgl',  // folder where `lessons` folder is
    lessonGrep: 'webgl*.md',  // grep to find .md files for lessons
    siteName: 'WebGLFundamentals',
    siteThumbnail: 'webglfundamentals.jpg',  // in rootFolder/lessons/resources 
    templatePath: 'build/templates',  // where the templates are
    owner: 'gfxfundamentals',  // owner of git repo
    repo: 'webgl-fundamentals',  // name of git repo
    thumbnailOptions: {
      thumbnailBackground: 'webglfundamentals.jpg',
      text: [
        {
          font: '100px lesson-font',
          verticalSpacing: 100,
          offset: [100, 120],
          textAlign: 'left',
          shadowOffset: [15, 15],
          strokeWidth: 15,
          textWrapWidth: 1000,
        },
      ],
    },
  };

  await buildStuff(buildSettings);
}

You can build specific lessons by passing in an array of filenames in the settings

{
  ...
  filenames: [
    'some-article.md',
    'another-article.md',
  ];
}

This is mostly to facilitate a continuous build. If you monitor for lesson article changing then you can pass the list of changed files to build just those files.

Note: the builder only builds index.html, the lesson html files, sitemap.xml, link-check.html, contributors.html, contributors.js, and atom.xml. It does not copy any other files. (examples, images, etc...). Use other build tools for that.

contributors.js is the list of contributors from github. By default this is bogus data of 2 entires. To get real data at build time set the environment variable LESSON_BUILDER_ENV to production in which case a request will be made to github. I would have preferred to use git but (a) git has no info about links to people. github at least as link I can insert. (b) git has no avatar links - I suppose here I could use gravatar but for now I opted to use github.

contributors.html is build from contributors.md and inserted into the index.template. It just assumes contributors.md is a manually edited file.

.templates

The build system looks for handlebars template files in build\templates. The main templates it expects are index.template which it uses for the index.html file for each language and lesson.template which it use for each lesson.

Available to the templates are the following variables.

settings is the buildSettings passed into the builder (see above)
langInfo is the contents of the langinfo.hanson file above.
langInfo.baseDirname: The basename of the language folder.

There is no good reason for this to be different than the langCode but it can be.
langInfo.home: The path to the home eg topic/lessons/ja

langInfo.carousel: Some JSON for Schema.org schema.

Example usage

<script type="application/ld+json">
{
  "@context":"https://schema.org",
  "@type":"ItemList",
  "itemListElement":
  {{{langInfo.carousel}}}
}
</script>

originalLangInfo is the contents of the english langinfo.hanson file

This is useful in a template with the stringify helper as you can do stuff like
```
<div>{{{stringify names="langInfo.toc,originalLangInfo.toc"}}}</div>
```
and have it insert either the language specific translation or fallback to the english.
content: The .md file converted to HTML
langs: An array of info for all available languages

Each entry includes
- language: The text from the langinfo.language
- url (the URL to the corresponding page for this language)
- relUrl (the relative URL for this language from this page)
  
  effective if this is "" then the page being generated is this language (not really)
Here is an example handlebars template generating a language <select> dropdown using langs
```
<select class="language">
{{#each langs}}
   <option value="{{url}}" {{{selected key="url" value="relUrl" re="index\.html" sub="" }}}>{{language}}</a>
 {{/each}}
</select>
```
title: The title of the lesson from the .md front matter
description: The description of the less from the .md from matter
src_file_name: the .md file
dst_file_name: the .html file being written
toc: ???
tocHTML: the language specific generated table of contents
url: The url of the page
relUrl: The relative url of the page
screenshot: url for a screenshot for meta tags
screenshotSize: the size of the screenshot
templateOptions: same as langInfo above. Just cruft.

handlebar helpers

include: Includes another template
```
{{{include "some/other/file"}}}
```

ifexists: Checks if a file exists

{{#ifexists filename="foo/{{bar}}/test.txt" bar={{langInfo.langCode}}}
   <div>it exists</div>
{{else}}
   <div>it does not exist</div>
{{/ifexists}}

example: Inserts an example using example.template
```
{{{example url="../some-example.html}}}
```
Optionally takes a caption, width, height, startPane
```
{{{example url="../example.html" caption="adjust slider" width="500" height="400"}}}
```
Passed to example.template are the width, height, caption, examplePath (so links are absolute), encodedUrl in case there is a query string url, cacheid for cache busting, params (which is whatever the startPane parameter was)
diagram: Inserts an diagram using diagram.template

Optionally takes a caption, width, height, and a className

Passed to diagram.template are the width, height, caption, examplePath (so links are absolute), url, className
image: Inserts an image using image.template

Optionally takes a caption, and a className
selected: Inserts the word selected. See langs
stringify: Insert the JSON.stringify(value) of the named value.

example const foo = {{{stringify names="langInfo.toc,originalLangInfo.toc"}}} will insert langInfo.toc if it exists else originalLangInfo.toc (the English)
warning: Inserts the warning template with a translated message.
escapehtml

Inside markdown you can insert code using triple backticks but sometimes you're embedding code in HTML in which case markdown is not processed.

To handle that you can use escapehtml. Example:
```
<pre class="prettyprint"><code>{{#escapehtml}}
  <div>
    <div>foo</div>
  </div>
{{/escapehtml}}</code></pre>
```
which will produce
```
<pre class="prettyprint"><code>
  &lt;div&gt;
    &lt;div&gt;foo&lt;/div&gt;
  &lt;/div&gt;
</code></pre>
```
NOTE: double brackets are required, triple brackets will fail!

markdown issues / notes

HTML blocks (vs inline) requires no blank lines

BAD !!

<div>
hello

world
</div>

Good

<div>
hello
world
</div>

Inline html infuriatingly has its content parsed as markdown

text <span class="equation">a*b*c</span> text

produces

<p>text <span class="equation">a<em>b</em>c</span> text</p>

space at end of line means break

abc<space>
def

produces <p>abc<br>def</p>

Debugging

You can set the following environment variables to help find issues.

ARTICLE_FILTER: only articles with this substring in the filename will be built
ARTICLE_VERBOSE: Set to 1, Prints more info (not much though)
ARTICLE_FIX: Set to 1, Tries to fix URLS

I don't totally remember what this is for but it loads an lesson .md file, tries to fix some URLs, then writes that .md file back out. So, be sure your originals are checked into git.
SHOW_CONTENT: Set to 1, shows various transformations

Testing

I started adding some tests to hopefully make it easy to um, test. Before this I had to use one of the other repos using this repo.

One test generates files in the out folder and then diffs them to the test/expected folder. If it prints a difference and you want to update the expectations you can use

UPDATE_EXPECTED=true npm test

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