[Bf-viewport] OpenGL ES compatibility

[Yuri Kovelenov]

Hi Brecht, guys,

I'd like to share our experience here in Blend4Web regarding target API 
level.
WebGL (which is essentially JavaScript binding to OpenGL ES 2.0 API) is 
supposed to run everywhere,
on desktops, mobiles, TVs, consoles, etc. This is theory - in practice, 
however,
some our users are reporting glitches, crashes or unavailability of 
WebGL on
different platforms - mainly because of driver issues (both proprietary 
and open source).
Upcoming WebGL 2.0 (counterpart of ES 3.0) will possibly bring even more 
problems since it offers
much wider feature set.

My point is that targeting OpenGL 2.1/ES 2.0 is already quite 
restrictive and will alienate some Blender users who will be
forced to update their hardware or stick to older Blender version. To my 
opinion, targeting OpenGL 3.x will result in significant decreasing
of Blender user base. This can be illustrated with the Unity3D stats - 
40% of Web Player users (general public on the Internet)
do not have DX 10+ (roughly corresponds to OpenGL 3.x-4.x) capabilities.
http://hwstats.unity3d.com/web/gpu.html (see picture at the bottom)

Accessibility has always been the main advantage of Blender. Being a 
FOSS tool, Blender is natural choice for CG beginners,
freelancers and small teams. Some of them cannot afford paying for 
expensive hardware. It is also often used on Linux where
open source drivers are often of bad quality and thus can lead to 
inability to run Blender.

In our team we would prefer if Blender targeted mandatory OpenGL ES 2.0 
with optional OpenGL ES 3.0 features
activated on supported platforms. This is how we are going to do with 
WebGL 1.0/2.0. The Google-maintained ANGLE open source
library suggested by Martijn Berger perhaps could be used as a backend 
to insure cross-platform performance
similar to Chrome and Firefox browsers which work literally everywhere. 
Targeting OpenGL ES is preferable over generic
desktop OpenGL due to better portability. This will lay groundwork for 
Blender to run on tablets and even as a PPAPI browser plug-in.

In any case what you are doing is already awesome. We are going to 
dedicate a programmer for the viewport project as well.

Best regards,

Yuri

Blend4Web Team
https://www.blend4web.com