The one funny outlier of the group is gl_FogCoord. I recommend that you pick attribute names that are contextually relevant, rather than trying to mimic these names. You'll see many desktop shaders that use the gl_MultiTexCoordX attribs as arbitrary data streams, often packing things like tangents or skinning data into them. Rather than exposing vertex streams to arbitrary attributes in the shader, they had pre-defined names they were associated with:Īlmost all of these are very straightforward attributes that don't require much guesswork, and they can all be replaced directly with attribute names of your choice. for example: glVertexPointer, glNormalPointer, and glTexCoordPointer. In OpenGL 2.0 there are a number of special cased variants of gl.vertexAttribPointer that imply specific semantics in the fixed function pipeline. Simple stuff, so you shouldn't have any trouble finding a reasonable way to replace ftransform() should you encounter it. Gl_Position = projectionMatrix * modelviewMatrix * vec4(position, 1.0) You can replace it entirely with a couple of matrix multiplies: In essence all that this does is instruct the shader 'Run my vertex through the standard fixed function transform logic.' It's a nice shortcut for developers coming from an older style of OpenGL development, but it's also not doing nearly as much work as you might think. Other logic here, setting up varyings, etc. Occasionally you will see vertex shaders that look like this: I felt this deserved it's own section, as it's one of the only functions explicitly provided to mimic fixed function pipeline behavior in a shader. (For a quick glance at everything available to OpenGL 2.0 shaders, check out this handy cheat sheet) If that sounds like you, then this is your guide! These can make a simple 'Oh just use this legacy shader' recommendation an exercise in frustration for someone who isn't intimately familiar with OpenGL 2.0 development on the desktop. There are, however, some oddities from the desktop relm that have (wisely) been excised from OpenGL ES 2.0, OpenGL 3.1+, and WebGL.

Typically it's only when you start looking at OpenGL 3+ (DirectX 10+) level hardware and applications do we run into things that are simply out of reach of WebGL as it stands today. When discussing graphical techniques in WebGL, it's not uncommon to hear people say 'Here's some shader code from an OpenGL desktop app! Use that!' And for the most part that's an entirely reasonable thing to say.

Gltexcoordpointer opengl es 2.0