WebGL Fundamentals

This is a series of lessons or tutorials about WebGL.

Unlike most WebGL lessons these are not based off of OpenGL. OpenGL is 20 years old. The lessons of OpenGL don't match well with WebGL. The APIs have changed too much. The ideas of OpenGL and OpenGL tutorials are out of date with WebGL, OpenGL ES 2.0 and the land of shaders.

I would argue that WebGL is actually a very simple API. What makes it appear complicated is the way in which it's used. The complications are added by the programmer. WebGL itself is simple.

These lessons try to show that simplicity and well as teach the fundamentals of 2D math and 3D math so readers can hopefully have an easier time writing their own WebGL programs and understanding the complexity that other programmers pile on top of simple WebGL.

This is work in progress. Feel free to contribute.

Contributing

Of course bug fixes are always welcome.

If you'd like to write a new article please try to always take one step at a time. Don't do 2 or more things in a single step. Explain any new math in the simplest terms possible. Ideally with diagrams where possible.

Translating

Each translation goes in a folder under webgl/lessons/<country-code>.

Required files are

langinfo.hanson
index.md
toc.html

`langinfo.hanson`

Defines various language specific options. Hanson is a JSON like format but allows comments.

Current fields are

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

  // 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: 'http://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="http://stackoverflow.com/questions/tagged/webgl">Ask on stackoverflow</a>.</div>\n        <div>Issue/Bug? <a href="http://github.com/greggman/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/greggman/webgl-fundamentals)! 😄\n\n[Here's the original English article for now]({{{origLink}}}).",

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

`index.md`

This is the template for the main page for each language

`toc.html`

This is the table of contents for the language. It is included on both the index and on each article. It's up to if you want to link to English articles for non-translated articles. The build system will create a placeholder for every English article for which there is no corresponding article in that langauge. It will be filled the missing message from above.

Translation notes

The build process will make a placeholder html file for each article has an english .md file in webgl/lessons but no corresponding .md file for the language. This is to make it easy to include links in one article that links to another article but that other article has not yet been translated. This way you don't have to go back and fix already translated articles. Just translate one article at a time and leave the links as is. They'll link to placeholders until someone translates the missing articles.

UI localization

Some of the diagrams allow passing translations for the UI and other text.

For example if there is a slider named "rotation" you can add "?ui-rotation=girar" at the end of the URL for the diagram. For 2 or more translations separate them with a &. Certain characters are disallowed in URLs like =, #, & etc. For those use their uri encoding.

For diagram labels you'll have to look inside the code. For example for the directional lighting diagram near the start of the code it looks like this

const lang = {
  lightDir: opt.lightDir || "light direction",
  dot: opt.dot || "dot(reverseLightDirection,surfaceDirection) = ",
  surface1: opt.surface1 || "surface",
  surface2: opt.surface2 || "direction",
};

Which means you can localize the labels like this

{{{diagram url="resources/directional-lighting.html?lightDir=光線方向&surface1=オブジェクト&surface2=表面方向&dot=dot(光線反対方向,表面方向)%20%3D%20&ui-rotation=角度" caption="方向を回転してみて" width="500" height="400"}}}

For testing reference the sample directly in your browser. For example

http://localhost:8080/webgl/lessons/resources/directional-lighting.html?lightDir=光線方向&surface1=オブジェクト&surface2=表面方向&dot=dot(光線反対方向,表面方向)%20%3D%20&ui-rotation=角度

To build

The site is built into the out folder

Steps

git clone https://github.com/greggman/webgl-fundamentals.git
npm install
npm run build
npm start

now open your browser to http://localhost:8080

TO DO

A list of articles I'd like to write or see written

lighting
- spot lighting
- normal maps
- shadow maps
geometry
- plane, cube, sphere, cone, disc, torus
  - lines vs triangles
  - indexed vs non
  - vertex colors
- .obj
- other
- pre-process (don't load .obj, .dae, .fbx etc at runtime)
- pre-optimize (texture atlas, sizes, combine meshes, etc...)
animation
- blendshapes
- hierarchical animation
- skinning
debugging
- debugging JS WebGL
  - example (https://goo.gl/8U5whT)
  - CHECK THE GAWD DAMN CONSOLE!
    - actually read the error message
    - understand it.
      - INVALID_ENUM means one of your gl.XXX values is not valid period
      - INVALID_VALUE means one of the int or float values is probably off
      - INVALID_OPERATION means something you tried to do won't work for the given state
      - texture not renderable
      - attribute out of range
      - check your framebuffers
      - check your extensions
  - make shorter samples (MCVE) See https://meta.stackoverflow.com/a/349790/128511
    - remove any code you don't need
    - get rid of CSS
    - get rid of HTML
    - consider using a POINT (no attributes needed)
    - don't use images if they are not relevant. Use a canvas or a single and double pixel texture
    - While creating this MCVE you'll often find the bug
- debugging a shader
  - set fragment shader to solid color.
  - render normals
  - render texcoords
  - render cube/sphere/plane
text
- glyph cache
post processing
- how to render to a texture (scene on cube)
- DOF
- glow
- light rays
- RGB glitch, CRT distortion, scanlines
- color mapping/tone mapping
Creative coding
- color palettes
- indexed everything
- tilemaps
- generated geometry
- histogram
- particles
- toon/ramp shading
- procedural textures
- vsa
- screen shaders (shadertoy)
  - https://stackoverflow.com/questions/4638317/how-to-implement-this-rotating-spiral-in-webgl
code organization
- scene graph
  - putting lights and camera in scene graph
Engine Creation
- culling
  - frustum culling
  - grid culling
  - quad tree / oct tree
  - portals (is this still a thing?)
  - PVS
- materials
- lighting DB
Physically based rendering

armno / webgl-fundamentals