Sign in to follow this  
tonnot

OpenGL VBO (Vertex Buffer Objects) and can I'm sure that today almost graph cards can support it ?

Recommended Posts

I have two ways to draw my wordl, vertex arrays or vertex buffer objects.
As I have readen, VBO are the best.
But I'm ask myself .... today I can be completely sure that it is supporte by almost all graphic cards ?
The fist version of opengl that suport it was 1.5 . OpenGL 2.0 was released on 2004.

So, Have I to duplicate my code to support both ways ? (arrays and VBO's ) ??

I have more doubts.
I have read :
[i][b]Legacy Note:[/b] Versions of OpenGL prior to 3.0 allowed the use of client-side data for vertex rendering, but GL 3.0 deprecated this. Core GL 3.1 and greater forbid client-side vertex data, so VBOs are the only means for rendering.
What means ?
Thanks[/i]

Share this post


Link to post
Share on other sites
[quote]So, Have I to duplicate my code to support both ways ? (arrays and VBO's ) ??[/quote]
That is up to you. If you want to support Intel stuff, then I suggest that you use D3D since their driver support is better.

[quote][i]What means ?[/i] [/quote]
It means that you should not create a forward compatible context. Create a legacy context so that you can use plain old vertex arrays.
In more specific terms, don't do what we do here http://www.opengl.org/wiki/Tutorials
Notice how we search for
WGL_ARB_create_context

Share this post


Link to post
Share on other sites
In my opinion, you should safely assume that OpenGL 2.1 is present, simply by making it a minimum requirement (and of course checking the version and aborting if it isn't).

The reasoning behind that is:
[list=1][*]it solves 90% of your headaches (VBO, PBO, FBO, non-POT) because you have a good working set of base functionality that is guaranteed[*]not half a million extra checks and 20 different code paths for all eventualities[*]every graphics card that is not 10 years old can do OpenGL 2.1[*]if OpenGL 2.1 is not supported, then [i]either [/i]it's a software fallback, and a really bad one too[*][i]or,[/i] the graphics card is so old/cheap that the user [i]will not have any fun either way[/i], because it does not have enough fillrate/memory/whatever[/list]
That said, vertex buffer objects are something that can easily be emulated in software (without any penalties) too, if the hardware really does not support them. Insofar, there is no excuse for VBO not being supported even on 10 year old hardware. Of course it won't be [i]magically [/i]faster, but it will work the same. If an implementation really doesn't support VBO, it is just hopelessly old (or hopelessly poor).

So, even [i]blindly [/i]assuming that VBO is always present (not even looking at the version or extension string) may be a valid point of view although it's of course incorrect.

[u]Ed:[/u]
Worded differently: If the most basic functionality is not present, you should conclude that it does not make sense to support this particular client at all. It is not in your client's interest having a game run at 1 FPS (or slower), and it is not in your interest dealing with the unavoidable support queries of this client.
Your interest is making it work for [u][i]as many people as reasonably possible[/i][/u], and making it work [u][i]well[/i][/u].

Making it work [i]badly [/i]for someone who did not care to spend $20 on a graphics card five years ago is not in the interest of anyone.

Note that you can even buy OpenGL 3.2/3.3 compatible cards for under $20 nowadays (which is why I personally don't target anything below version 3.2 at all any more, it just does not warrant the trouble of maintaining extra codepaths -- the people who can't (or don't want to) afford a $20 card can't (or don't want to) afford to pay you either, so putting extra work in supporting them means only to put extra work in people who will only pirate your stuff). Edited by samoth

Share this post


Link to post
Share on other sites
[quote name='samoth' timestamp='1311157964' post='4837879']
In my opinion, you should safely assume that OpenGL 2.1 is present, simply by making it a minimum requirement (and of course checking the version and aborting if it isn't).

The reasoning behind that is:
[list=1][*]it solves 90% of your headaches (VBO, PBO, FBO, non-POT) because you have a good working set of base functionality that is guaranteed[*]not half a million extra checks and 20 different code paths for all eventualities[*]every graphics card that is not 10 years old can do OpenGL 2.1[*]if OpenGL 2.1 is not supported, then [i]either [/i]it's a software fallback, and a really bad one too[*][i]or,[/i] the graphics card is so old/cheap that the user [i]will not have any fun either way[/i], because it does not have enough fillrate/memory/whatever[/list]
That said, vertex buffer objects are something that can easily be emulated in software (without any penalties) too, if the hardware really does not support them. Insofar, there is no excuse for VBO not being supported even on 10 year old hardware. Of course it won't be [i]magically [/i]faster, but it will work the same. If an implementation really doesn't support VBO, it is just hopelessly old (or hopelessly poor).

So, even [i]blindly [/i]assuming that VBO is always present (not even looking at the version or extension string) may be a valid point of view although it's of course incorrect.

[u]Ed:[/u]
Worded differently: If the most basic functionality is not present, you should conclude that it does not make sense to support this particular client at all. It is not in your client's interest having a game run at 1 FPS (or slower), and it is not in your interest dealing with the unavoidable support queries of this client.
Your interest is making it work for [u][i]as many people as reasonably possible[/i][/u], and making it work [u][i]well[/i][/u].

Making it work [i]badly [/i]for someone who did not care to spend $20 on a graphics card five years ago is not in the interest of anyone.

Note that you can even buy OpenGL 3.2/3.3 compatible cards for under $20 nowadays (which is why I personally don't target anything below version 3.2 at all any more, it just does not warrant the trouble of maintaining extra codepaths -- the people who can't (or don't want to) afford a $20 card can't (or don't want to) afford to pay you either, so putting extra work in supporting them means only to put extra work in people who will only pirate your stuff).
[/quote]

I'd +2 this if I could; awesome advice and seconded all the way.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

Sign in to follow this  

  • Forum Statistics

    • Total Topics
      627719
    • Total Posts
      2978790
  • Similar Content

    • By DelicateTreeFrog
      Hello! As an exercise for delving into modern OpenGL, I'm creating a simple .obj renderer. I want to support things like varying degrees of specularity, geometry opacity, things like that, on a per-material basis. Different materials can also have different textures. Basic .obj necessities. I've done this in old school OpenGL, but modern OpenGL has its own thing going on, and I'd like to conform as closely to the standards as possible so as to keep the program running correctly, and I'm hoping to avoid picking up bad habits this early on.
      Reading around on the OpenGL Wiki, one tip in particular really stands out to me on this page:
      For something like a renderer for .obj files, this sort of thing seems almost ideal, but according to the wiki, it's a bad idea. Interesting to note!
      So, here's what the plan is so far as far as loading goes:
      Set up a type for materials so that materials can be created and destroyed. They will contain things like diffuse color, diffuse texture, geometry opacity, and so on, for each material in the .mtl file. Since .obj files are conveniently split up by material, I can load different groups of vertices/normals/UVs and triangles into different blocks of data for different models. When it comes to the rendering, I get a bit lost. I can either:
      Between drawing triangle groups, call glUseProgram to use a different shader for that particular geometry (so a unique shader just for the material that is shared by this triangle group). or
      Between drawing triangle groups, call glUniform a few times to adjust different parameters within the "master shader", such as specularity, diffuse color, and geometry opacity. In both cases, I still have to call glBindTexture between drawing triangle groups in order to bind the diffuse texture used by the material, so there doesn't seem to be a way around having the CPU do *something* during the rendering process instead of letting the GPU do everything all at once.
      The second option here seems less cluttered, however. There are less shaders to keep up with while one "master shader" handles it all. I don't have to duplicate any code or compile multiple shaders. Arguably, I could always have the shader program for each material be embedded in the material itself, and be auto-generated upon loading the material from the .mtl file. But this still leads to constantly calling glUseProgram, much more than is probably necessary in order to properly render the .obj. There seem to be a number of differing opinions on if it's okay to use hundreds of shaders or if it's best to just use tens of shaders.
      So, ultimately, what is the "right" way to do this? Does using a "master shader" (or a few variants of one) bog down the system compared to using hundreds of shader programs each dedicated to their own corresponding materials? Keeping in mind that the "master shaders" would have to track these additional uniforms and potentially have numerous branches of ifs, it may be possible that the ifs will lead to additional and unnecessary processing. But would that more expensive than constantly calling glUseProgram to switch shaders, or storing the shaders to begin with?
      With all these angles to consider, it's difficult to come to a conclusion. Both possible methods work, and both seem rather convenient for their own reasons, but which is the most performant? Please help this beginner/dummy understand. Thank you!
    • By JJCDeveloper
      I want to make professional java 3d game with server program and database,packet handling for multiplayer and client-server communicating,maps rendering,models,and stuffs Which aspect of java can I learn and where can I learn java Lwjgl OpenGL rendering Like minecraft and world of tanks
    • By AyeRonTarpas
      A friend of mine and I are making a 2D game engine as a learning experience and to hopefully build upon the experience in the long run.

      -What I'm using:
          C++;. Since im learning this language while in college and its one of the popular language to make games with why not.     Visual Studios; Im using a windows so yea.     SDL or GLFW; was thinking about SDL since i do some research on it where it is catching my interest but i hear SDL is a huge package compared to GLFW, so i may do GLFW to start with as learning since i may get overwhelmed with SDL.  
      -Questions
      Knowing what we want in the engine what should our main focus be in terms of learning. File managements, with headers, functions ect. How can i properly manage files with out confusing myself and my friend when sharing code. Alternative to Visual studios: My friend has a mac and cant properly use Vis studios, is there another alternative to it?  
    • By ferreiradaselva
      Both functions are available since 3.0, and I'm currently using `glMapBuffer()`, which works fine.
      But, I was wondering if anyone has experienced advantage in using `glMapBufferRange()`, which allows to specify the range of the mapped buffer. Could this be only a safety measure or does it improve performance?
      Note: I'm not asking about glBufferSubData()/glBufferData. Those two are irrelevant in this case.
    • By xhcao
      Before using void glBindImageTexture(    GLuint unit, GLuint texture, GLint level, GLboolean layered, GLint layer, GLenum access, GLenum format), does need to make sure that texture is completeness. 
  • Popular Now