Sign in to follow this  
deavik

OpenGL Opengl and graphics cards

Recommended Posts

I don't know much about the basics of how opengl works, ie how it interacts with the hardware ... but here are some questions I was asking myself: 1. Most people on this forum who have tested my code or anything have quality cards like GeForces and the like ... but lots of people I know use the Intel 810 graphics driver (poor souls). How will GL programs do in hardware like that? 2. Similar to the previous question, as we say move back in time in the development of graphics hardware ... in what ways will the performance of the application be affected except for just frame rate? 3. If you remember, old games such as NFSIII had a "Software render" option. What is that all about? 4. Some GL extensions, as far as I know, are vendor specific, aren't they? How do I know which extensions will work where? Related: What are the GL_ARB extensions? Do they have any hardware dependence, or will just having the latest runtime do? Sure I will compile with the latest headers, but what about the runtime? 5. How does DirectX compare with OpenGL on the above counts of compatibility? Thanks in advance for taking time out to answer!

Share this post


Link to post
Share on other sites
Quote:
Original post by deavik
I don't know much about the basics of how opengl works, ie how it interacts with the hardware ... but here are some questions I was asking myself:

1. Most people on this forum who have tested my code or anything have quality cards like GeForces and the like ... but lots of people I know use the Intel 810 graphics driver (poor souls). How will GL programs do in hardware like that?

2. Similar to the previous question, as we say move back in time in the development of graphics hardware ... in what ways will the performance of the application be affected except for just frame rate?

3. If you remember, old games such as NFSIII had a "Software render" option. What is that all about?

4. Some GL extensions, as far as I know, are vendor specific, aren't they? How do I know which extensions will work where? Related: What are the GL_ARB extensions? Do they have any hardware dependence, or will just having the latest runtime do? Sure I will compile with the latest headers, but what about the runtime?

5. How does DirectX compare with OpenGL on the above counts of compatibility?

Thanks in advance for taking time out to answer!



1. never heard of it, so i wouldn't have the highest of hopes

2. unless you make your program frame rate dependant( game physics, etc ) or if the gl commands to update screen( i use SDL, so my SDL_GL_SwapBuffers() ) blocks until drawing completes

3. software renderer - use the processor instead of a graphics card. slow
http://www.mesa3d.org/ i think this does software...

4. dont use them yet

5. directx is windows only , thats the only compatability issue i need.

Share this post


Link to post
Share on other sites
Quote:
Original post by deavik
I don't know much about the basics of how opengl works, ie how it interacts with the hardware ... but here are some questions I was asking myself:

1. Most people on this forum who have tested my code or anything have quality cards like GeForces and the like ... but lots of people I know use the Intel 810 graphics driver (poor souls). How will GL programs do in hardware like that?

Depends on the quality of the driver and the hardware. In general the i810 aren't bad if you're just pushing a few textured polys, but they're missing lots of features.

Quote:
2. Similar to the previous question, as we say move back in time in the development of graphics hardware ... in what ways will the performance of the application be affected except for just frame rate?

Older cards won't have as many features. If you're using basic GL 1.1 then you're fine. If you start using extentions you need to check if these are available first (typically you'll be using at least multitexturing, which is an extension).

Quote:
3. If you remember, old games such as NFSIII had a "Software render" option. What is that all about?

What it says on the tin. Ignores the graphics card and does everything on the CPU.

Quote:
4. Some GL extensions, as far as I know, are vendor specific, aren't they? How do I know which extensions will work where? Related: What are the GL_ARB extensions? Do they have any hardware dependence, or will just having the latest runtime do? Sure I will compile with the latest headers, but what about the runtime?

ARB extensions are vendor-independant and usually availible on lots of hardware. Ideally stick with these whenever possible. You can use glGetString(GL_EXTENSIONS) so your code can determine at run time what extensions are available and which aren't. Theres a whole section on extensions in the forum FAQ.

Quote:
5. How does DirectX compare with OpenGL on the above counts of compatibility?

Depends on the drivers, but usually about the same.

Share this post


Link to post
Share on other sites
Thanks for the replies! glGetString(GL_EXTENSIONS) seems to be the best way to do things for now. And I read in a wiki article that on Vista they would clamp to a Opengl 1.4 version support. I don't need to worry, though, till date I haven't used a single extension except for GL_BGR_EXT!

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
      627741
    • Total Posts
      2978887
  • 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