Author Topic: Opengl ES resources  (Read 3837 times)

0 Members and 1 Guest are viewing this topic.

Charles Pegge

  • Admin Support Member
  • *****
  • Posts: 3745
    • Oxygen Basic
Opengl ES resources
« on: August 23, 2012, 02:50:50 AM »
Some nice tutorials here:

http://www.learnopengles.com/

Charles Pegge

  • Admin Support Member
  • *****
  • Posts: 3745
    • Oxygen Basic
Re: Opengl ES resources
« Reply #1 on: August 26, 2012, 02:58:46 AM »
Tutorials:

Demonstrated the i-phone (2009-2010)

Excellent description of Transform Matrices in Tutorial 7

http://iphonedevelopment.blogspot.co.uk/2009/05/opengl-es-from-ground-up-table-of.html

John

  • Hero Member
  • *****
  • Posts: 3249
Re: Opengl ES resources
« Reply #2 on: August 26, 2012, 08:20:19 PM »
For the record, I'm only willing to support the O2C emitter on the Linux platform. Both MS and Apple have closed OS solutions which increase the risk factor in these volatile (mobile centric) times.

kryton9

  • Hero Member
  • *****
  • Posts: 721
Re: Opengl ES resources
« Reply #3 on: August 26, 2012, 10:12:07 PM »
I went to try out the free visual studio 2012 c++ tonight and it crashed and burned halfway into the install.
But to be fair, I had installed the latest ubuntu into a virtual box machine to try to get the beta 5 of QT and I followed the tutorial step by step and couldn't get it to work either.
I know it is probably user error, but I like to blame the operating systems :)

John

  • Hero Member
  • *****
  • Posts: 3249
Re: Opengl ES resources
« Reply #4 on: August 26, 2012, 11:13:13 PM »
I'm running Ubuntu 12.04 LTS that is suppose to be the gold standard as far as their distribution of Linux goes but ARM is like an orphan to them. I still haven't seen what the real plan for Ubuntu on a tablets is. I'm happy for the moment with my chroot setup on Android but I feel like I'm going it alone.


Charles Pegge

  • Admin Support Member
  • *****
  • Posts: 3745
    • Oxygen Basic
Re: Opengl ES resources
« Reply #5 on: August 27, 2012, 05:39:22 AM »
Opengl ES should look much the same whether on Android or Apple.

But One potential problem I read about is the Android emulator does not emulate Opengl ES. I don't know whether this has changed recently.

Charles

John

  • Hero Member
  • *****
  • Posts: 3249
Re: Opengl ES resources
« Reply #6 on: August 27, 2012, 09:37:49 AM »
I would install the iPad emulator on my laptop but I'm afraid Apple would claim that the Android emulator runs on the same host and therefore violates their patients of emulation.

Charles Pegge

  • Admin Support Member
  • *****
  • Posts: 3745
    • Oxygen Basic
Re: Opengl ES resources
« Reply #7 on: August 27, 2012, 10:56:22 AM »

It's really the OpenglES constraints I am investigating, it just happens to be an iphone site hosting the tutorial.

OpenGl does not implement a number of functions used in classical OpenGl: Texturing and Lighting have to be done using Vertex and Fragment Shaders. The familiar glVertex calls also disappear and one has to use Vertex Buffer Objects (VBOs) instead. This is also the trend with OpenGl 3.0 and above. They want to deprecate the older technology, in favour of the greater computational flexibilty available in the newer generation of Graphics processors. Petr Schreiber warned us about this.

Charles

efgee

  • Full Member
  • ***
  • Posts: 172
Re: Opengl ES resources
« Reply #8 on: August 27, 2012, 11:40:07 AM »
I'm running Ubuntu 12.04 LTS... but ARM is like an orphan to them. I still haven't seen what the real plan for Ubuntu on a tablets is.

Ubuntu says:
In every dual-core phone, there’s a PC trying to get out: There is a Ubuntu for Android.
Can't tell you if it's any good (haven't had time to try it out yet...)


John

  • Hero Member
  • *****
  • Posts: 3249
Re: Opengl ES resources
« Reply #9 on: August 27, 2012, 07:27:06 PM »
Quote
Can't tell you if it's any good (haven't had time to try it out yet...)

Unless you're a commercial phone/tablet vendor, I doubt if you will be able to get it otherwise. If you find a download link, let me know, I'll give it a spin.

Petr Schreiber

  • Guest
Re: Opengl ES resources
« Reply #10 on: August 28, 2012, 12:36:48 AM »
Hi Charles,

if you want to avoid use of shaders, and use glTranslate, glRotate and other friends, you can still use the OpenGL 1.X ES context. For most tasks it is still powerful enough. I tried it on HTC phones at work and it behaved nicely (Android + Java).

On desktops, it is still supported to use fixed pipeline, even in OpenGL 4.X, you just have to create compatibility context instead of core. There is no performance hit using compatibility context, right the opposite, I remember the talk on OpenGL forums that the core context was a bit slower, because it had to do more checking to trigger invalid function usage errors :) But I guess that was the case mostly in the early implementations, now I observe no difference.


Petr

Charles Pegge

  • Admin Support Member
  • *****
  • Posts: 3745
    • Oxygen Basic
Re: Opengl ES resources
« Reply #11 on: August 28, 2012, 01:12:18 AM »

Hi Petr,

I think time spent on shaders is a good investment. I am particularly interested in shader lighting.

GLSL is of course  built into OpenGl, and I am curious to know how this compares with using Cg, which I have not played with yet.

I want to ensure that we can easily tap into the best platform-independent GL resources available on the web.

Charles

Petr Schreiber

  • Guest
Re: Opengl ES resources
« Reply #12 on: August 29, 2012, 12:09:05 PM »
Hi Charles,

I think desktop GLSL is getting better (features and implementation quality) comparing to previous revisions. On mobile devices, I have not enough experience to judge it.

I think the specific syntax does not matter - once brain is ready for data parallel calculations, it can jump between specific implementations without bigger issues :)

I agree learning shader programming is very important!


Petr