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Deleting a Texture

Started by medevilenemy Apr 13, 2009 at 12:05 AM 3 replies 1.2k views

Original Post

Apr 13, 2009 at 12:05 AM

I've been trying to figure out how to unload my textures after I no longer need them, but I can't seem to figure out how. This is how I generate an individual texture:


    glBindTexture(GL_TEXTURE_2D, texnum);
    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_NEAREST);
    glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
    glTexImage2D(GL_TEXTURE_2D, 0, 4, infoheader.biWidth, infoheader.biHeight, 0, GL_RGBA, GL_UNSIGNED_BYTE, texture);
    gluBuild2DMipmaps(GL_TEXTURE_2D, 4, infoheader.biWidth, infoheader.biHeight, GL_RGBA, GL_UNSIGNED_BYTE, texture);
    free(texture);

where texture is temporary storage for the texture data while it was being loaded and generated. after free(texture); the texture data does not exist locally anymore... I think opengl stores it internally at that point -- so I can only access individual textures through their texture ids (texnum). Is there any way to delete a texture from within opengl knowing only its texture id?

Zakwayda

Apr 13, 2009 at 12:15 AM

Is glDeleteTextures() what you're looking for?

medevilenemy

Apr 13, 2009 at 7:37 PM

it seems to be the correct function, but all the references on its use i've found use it to delete out of local storage (variables). I need a way to delete textures from wherever opengl stores them (the only way I can access them is through binding their tex ids)

mightypigeon

Apr 13, 2009 at 8:31 PM

Quote:
glDeleteTextures deletes n textures named by the elements of
the array textures. After a texture is deleted, it has no
contents or dimensionality, and its name is free for reuse
(for example by glGenTextures). If a texture that is
currently bound is deleted, the binding reverts to 0 (the
default texture).

So in your original example you would simply do something like:

glDeleteTextures( 1, &texnum );

The second parameter of glDeleteTextures is simply a pointer to a list of texture object ID's. It lets you do something like this

GLuint textures[5];textures[0] = loadtexture( "texture1.tga" );textures[1] = loadtexture( "texture2.tga" );...etc...glBindTexture( GL_TEXTURE_2D, textures[0] );then later onglDeleteTextures( 5, textures );

It's the same as glGenTextures, just in reverse :)

medevilenemy

Apr 13, 2009 at 11:13 PM

that would work? Wow, thanks. My apologies for my denseness, I wasn't entirely certain how glDeleteTextures worked. Thanks again!

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