Sign in to follow this  
mikealexander

OpenGL newbie has a problem w/ tga.

Recommended Posts

I hate to bother everyone with this, but I haven't been able to fix it by myself after several hours at it (like, 12). I have been working on tga loading code to load textures for an opengl scene. Everything appears to be alright, at least up to the actual image data. But when I go to texture an object in my scene, the square remains white... I was wondering if somebody could take a look through my code to see if they can find my screw-up? you can get the files here: PELoadTGA.cpp PELoadTGA.h Just as a forewarning, the code is probably a bit ugly, and there may be some incorrect naming conventions and such, but I'm sure you can figure it out. also, before anyone suggests I use code thats already out there, I'm trying to do this my own way (somewhat) so I can learn how it all works. Thanks for the help, and God bless! Mike (Im using dev-cpp if that matters)

Share this post


Link to post
Share on other sites
If the image appears to load correct, but the texturing is wrong, why show the image loading code which appears to work and not the texturing code which appears to not work?

Check the usual things like unsuported texture size (possible power of two limits) and filtering mode (default minification filter requires a complete mipmap set).

Share this post


Link to post
Share on other sites
Square remaining white usually means the data wasn't uploaded correctly, or you haven't enabled GL_TEXTURE_2D (or you have fog cranked up on white, or light.. but I doubt that's your problem).

Hope that helps,
~Zix

Share this post


Link to post
Share on other sites
Use GLAUX or something similar to load a simple BMP and use it with the same texturing code you use - if that doesn't work you probably texture incorrectly(and TGA loading might actually work).

If that does work, write a TGA saving routine, and then look at what you actually loaded.

Share this post


Link to post
Share on other sites
Thanks for the replies. I am reusing the code I have for a working bitmap loader, and so I know it isn't the texturing thats the problem. And I've been using iostream.h and debugging to watch all the variables throughout execution. The stuff seems to be right up until I actually loop through to load the image data.

Share this post


Link to post
Share on other sites
Does the fact that you call CleanupImage(); at the end of the loading procedure before I see any OpenGL upload code mean anything? This seems to be the problem... the rest of your code looks fine.

~Zix

Share this post


Link to post
Share on other sites
nope, never mind. I thought I commented out something needed, but I didn't, thats all good.

zix99 That part of the code is fine I think (if not logically, trial and error proves it)

Seroja - I tried your suggestion. The tga file that came out was corrupted in some way. So either I messed up that code too or the problem is with the actual loading.

Share this post


Link to post
Share on other sites
hang on a sec mikealexander:

don't dismiss zix99's observation so quickly:

tell me you are not deleting the texture as soon as you load it.

the code you presented loads the texture then promptly deletes it
with CleanupImage()!

Or are you magically hiding the gl code that must upload the texture to video memory before you use CleanupImage().

I expected to see something like:

//maybe Generate OpenGL texture IDs
glGenTextures(1, &ID);
//maybe Bind the texture to a texture object
glBindTexture(GL_TEXTURE_2D, ID);

// but definitely load up with
gluBuild2DMipmaps(..,..,..,..,ucImgData)
//and/or
GL_TEXTURE_2D.(..,..,..,..,ucImgData)

// before you delete ucImgData!

Share this post


Link to post
Share on other sites
Alright, I apologize zix99 ;), and thatnks for pointing that out Steven. You were definitively right. I don't know how I missed that... (actually no, I may know that; 5 hours of sleep in 2 nights?!)

I had thought of generating the textures there already, but when I did I must have slipped it in after a call to the cleanup function.

Thanks everyone! That really helps!

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
      627764
    • Total Posts
      2978976
  • 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