An Overview of Phong Shading in GLSL

https://github.com/stackgl/glsl-lighting-walkthrough

by mattdesl • 11 years ago

46 13 11 years ago

yoklov5• 11 years ago

Does `#pragma glslify : foo = require('foo')` leave an awful taste in anyone elses mouth?

Not sure if it's because it's totally opaque, or because it adds a dependency and potentially a whole heap load of transitive dependancies. You're putting your game/app/whatever's performance in the hand of someone else (moreso than for infrequently run CPU code), not only hoping they didn't write a crappy implementation of whatever, but hoping nothing they depended on did either.

Not to mention, they might have done it differently than you would. For example, lots of times you want to do gamma correction using square/square root, and not using pow 2.2 (monitors vary so much that this is in all likelihood just as/nearly as correct, and it's vastly cheaper).

... Also, you'd think in a discussion about how to do most of these things, they'd actually show the code and not just say 'oh a library magically handles it'

mattdesl2• 11 years ago

In most cases the public modules (like glsl-perturb-normal) exist so you can get things up and running quickly. After you're happy with the results, if you've benchmarked and found the shaders are causing performance issues, it is trivial to fork the modules and tweak things by hand, or just inline functions as you see fit.

Anyways, thanks for the comments. Modular programming has a lot of merits, but it isn't for everybody. :)

jawngee• 11 years ago

As someone who writes a lot of glsl (for effects for a video editor, not for 3D), I ended up writing my own preprocessor to include dependencies (and to "patch" differences between GLSL ES and regular GLSL). Package management is the next logical step, so I personally don't see a problem with it.

It's like anything, you're not just going to dump a third party library into your code and hope for the best. You're going to see if it does the job, does the job well, and if it doesn't - you'll figure something else out.

codeka• 11 years ago

This is something I really miss from a few years ago when I was using Cg to do my shaders. It had (what I would consider) fairly basic features like #include and the ability to specify texture states and so on within the shader file. Now I have to do all of that manually, or write my own preprocessor or something...

moron4hire2• 11 years ago

Isn't... isn't that the case with literally all code? At some point you just have to give up on this fantasy that you'll write every last instruction and just call out to a library somewhere.

Game code isn't magic, despite how much game programmers want to act like it is.

yoklov5• 11 years ago

Shader code is extremely performance sensitive, and poorly written or complex shaders can absolutely destroy framerate.

Conditionals, loops, and even function calls on bad drivers are all things that need to be avoided, when possible, and it's very rare you can get ship a game without having to spend time optimizing your shaders.

bhouston• 11 years ago

Nice tutorial. :) It is impressive the breath of glslify coverage there is.

An Overview of Phong Shading in GLSL

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