Sign in to follow this  
Trapper Zoid

OpenGL What level of stencil/depth buffer support can I assume?

Recommended Posts

I am presently working on a hobby 2D game project, using textured quads in OpenGL (and SDL) to display my sprites. Previously I have only been using OpenGL as an easy way of transforming and rotating sprites, but for this game I would like to play around with a few more advanced effects. I have between reading up in my copy of the OpenGL Superbible on the various hardware buffers available, and am starting to come to grips with at least the theory of how most of those are meant to work (or at least I think so). However one question I have revolves around the functionality offered by the hardware available in today's computers. Thinking things through most of the effects I'd like to implement in my 2D games such as shadows and transition effects could be done with masking, whether implemented via the stencil buffer or the depth buffer. However given I am not very knowledgeable about the capabilities of graphics hardware I am unsure exactly what functionality I can expect in standard computers today. From what I have read I assume I can expect at least a one bit stencil buffer under OpenGL, even if that is implemented via software emulation. I am uncertain about the depth buffer, but I expect an OpenGL implementation has to at least have one, although to what bit depth I am unsure. But I don't know what is reasonable to assume for a halfway decent computer these days. I don't particularly need to put in a lot of special effects so I don't want to use a feature that limits my game to higher-end graphics cards, and from the date of some of the articles I've read on the internet and here at GameDev suggest that most computers would have more than enough for my 2D games. But exactly what can I expect a computer to do? Sorry if this is a bit vague or newbie-ish, as I'm pretty new to OpenGL and gaming hardware related topics. Thanks in advance for any replies.

Share this post

Link to post
Share on other sites
well, you can't assume anything, but I think most cards support 24/8 these days, 24-bit depth and 8-bit stencil. You can query the formats in windows to find out all the supported formats of a card.

Share this post

Link to post
Share on other sites
Original post by GrumpyAndTired
well, you can't assume anything, but I think most cards support 24/8 these days, 24-bit depth and 8-bit stencil. You can query the formats in windows to find out all the supported formats of a card.

Thanks - that's the impression I got. Am I right though in assuming that OpenGL is assured to have a depth buffer of at least 8 bit resolution? Given my game is fairly simple in 2D it's possible I could fudge the functionality I need for masking using the depth buffer. I'd prefer to use the buffer that's most widely supported if possible.

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
    • Total Posts
  • 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.  
      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