From: Ilmari Heikkinen <kig@...>
Date: 2005-04-16T06:10:37+09:00
Subject: Texture management strategies?

Hello, I'm writing this OpenGL engine thing, and am currently wondering 
about a good way to manage loading, replacing and disposing of 
textures.

It's doable to preload 20 images as rgba data into system memory, but 
trying to preload them into GL textures gets very slow. So there's a 
need to load textures into GL on the fly and delete unused textures.

This is roughly what I'm currently doing every three seconds in a 
slideshow program:

tex_id = renderer.textures[image.texture.object_id]
if tex_id
   image_filename = images[counter]
   GL.PushAttrib(GL::TEXTURE_BIT)
     GL.BindTexture(TEXTURE_2D, tex_id)
     bitmap = load_image(image_filename)
     GL.TexImage2D(TEXTURE_2D,
         0, 4,
         bitmap.width, bitmap.height,
         0, color_mode, pixel_format,
         bitmap.pixels)
   GL.PopAttrib()
end

It's not very pretty... Instead of the whole 
bindtexture-texsubimage2d-exposing-graphics-API-blah, I'd like to do 
this:

image.texture = images[counter]

And have the texture manager take care of disposing unused textures.


image.replace_texture( images[counter] )

Would be an alternative for cases where the texture size stays the same 
but the contents change (like with video.)


But I haven't really done this sort of stuff before. Any pointers on 
where to start or what would be a good way to do this? Books on the 
subject ?:)


Grateful for any help
- Ilmari