gluBuild2DMipmaps?

OpenGL OpenGL: Basic Coding
1

In the docs for gluBuild2DMipmaps, it says:


int gluBuild2DMipmaps(
  GLenum target,
  GLint components,
  GLint width,
  GLint height,
  GLenum format,
  GLenum type,
  const void *data
);

components 
The number of color components in the texture. Must be 1, 2, 3, or 4.

However, I see some OpenGL examples using internalformat, such as GL_RGB8, for the components argument instead.
The internalformat argument belongs to glTexImage2D():


void glTexImage2D(
  GLenum target,
  GLint level,
  GLint internalformat,
  GLsizei width,
  GLsizei height,
  GLint border,
  GLenum format,
  GLenum type,
  const GLvoid *pixels
);

Just wondering if the docs for gluBuild2DMipmaps are wrong, out-dated, or incomplete.

2

Yes, components IS internalformat however gluBuild2DMipmaps is not necessary anymore. Let the hw handle it with

glTexParameteri(GL_TEXTURE_2D, GL_GENERATE_MIPMAP, GL_TRUE);

See
http://www.opengl.org/wiki/index.php/Texture_Mapping

3

Thanks! That looks much better. No confusing arguments. I suppose if I wanted to “turn off” mip-mapping for a texture that
was already created using this method, I could just set GL_TRUE to GL_FALSE and call it again?

Or perhaps I have to delete the textureID to get rid of the mimaps?

4

glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR OR GL_NEAREST) turns off.

5

What I mean is, calling GL_GENERATE_MIPMAP with GL_TRUE allocates texture memory for mipmapping.

I’m assuming calling GL_GENERATE_MIPMAP with GL_FALSE de-allocates this mipmap texture memory, rather than
just “suspending” its use.

6

The specification doesn’t say, so it is implementation dependent.
See page 178 “Automatic Mipmap Generation” (or 192 shown in Adobe Reader)