No, I understand that point. I just don't agree with it in this case.
* "thou shalt not break working code". That's not some Universal Code of Software Engineering, that's just something he made up.
* No one in their right mind would expect you could port 20 year old C using OpenGL 1.x code to an iPhone with no effort.
* There are plenty of reasons APIs can benefit from breaking changes. Security fixes, major architectural improvements, platform porting, even general evolution and modernization. The question is always one of cost/benefit, relative pain vs relative gain.
* Sorry JWZ, but your X screensaver project is actually not an overriding concern driving the evolution of OpenGL ES.
* I didn't mention it again because so many other have pointed this out, but this isn't even the same API. OpenGL ES is not the same thing as OpenGL 1.x.
* Changing the major version number is a common and accepted way to indicate breaking changes are present in an API. The OpenGL board went even farther and gave it a different name and a different versioning scheme specifically because it is different.
"Sorry JWZ, but your X screensaver project is actually not an overriding concern driving the evolution of OpenGL ES."
Seriously, if you think that's a valid response, then you did not understand his point. Repeating something does not make it any more valid an argument.
OK I re-read his post. I think I understand his point. He has a something of a valid point, but what he is raising are considerations, not overriding principles.
If he wants to write his code by treating these as "thou shalt not" type laws, that's fine. He can criticize others for not following the same principles. But calling a bunch of top graphics engineers "idiots" because they looked at a vastly different engineering problem with different priorities and arrived at a different design is rude and ignorant and it reflects poorly on JWZ.
JWZ makes this statement: "Your users have code that works."
He is simply wrong about this.
* No one had working OpenGL ES code before OpenGL ES was standardized. This is by definition and one cannot argue the definition of OpenGL ES with the OpenGL standardization body itself.
* Even if you wanted to accept the mistake of thinking of the existing OpenGL 1.x codebase was supposed to be forwards compatible with ES, it's not true in the main. The amount of existing OpenGL 1.x that could plausibly benefit from being ported to embedded devices is insignificant. Seriously, JWZ may have just ported most of it.
This is what I mean by "X screensaver project is actually not an overriding concern driving the evolution of OpenGL ES."
JWZ seems to think that his principles of software engineering are the only correct way to look at it. He goes so far as to say "If you don't agree with that, then please, get out of the software industry right now. Find another line of work. Please."
To support such absolute claims and broad sweeping statements he uses a toy porting project that takes three days. The vendors who participate in the OpenGL ARB are concerned with projects that take 3 years and APIs that persist for more than 20! Don't you think they actually might know a thing or two about APIs and engineering them for software? Don't you think they might know extremely well what the costs of failed backwards compatibility are?
But that's OK, everybody scratches their head for a bit trying to sort out the different flavors of graphics APIs. Even single-vendor Direc3D has similar issues. If this is the most confusing thing about OpenGL to him and he can do something useful with OpenGL ES in his first three days of messing with it, he is a really really smart guy.
It showed that some existing code with a shim containing a reimplementation of a small subset of OpenGL 1.3 could be made to run acceptably fast on a rather beefy example of 2012's mobile hardware.
It certainly did not show that there was no need to exclude those calls back in 2003 when they were originally not included in OpenGL ES.
Yet another incomplete ad-hoc extended subset of OpenGL 1.x functionality lacking documentation, regression and performance tests, a stable and committed team of maintainers, ...
That is a noble goal, but it's one of hundreds of often-conflicting noble goals. It's not inherently wrong to design a toaster that fails to work as a refrigerator.
