OpenGL and monochrome texture - c++

Question

Is it possible to pump monochrome (graphical data with 1 bit image depth) texture into OpenGL?
I'm currently using this:
glTexImage2D( GL_TEXTURE_2D, 0, 1, game->width, game->height, 0, GL_LUMINANCE, GL_UNSIGNED_BYTE, game->culture[game->phase] );
I'm pumping it with square array of 8 bit unsigned integers in GL_LUMINANCE mode (one 8 bit channel represents brightness of all 3 channels and full alpha), but it is IMO vastly ineffective, because the onlu values in the array are 0x00 and 0xFF.
Can I (and how) use simple one-bit per pixel array of booleans instead somehow? The excessive array size slows down any other operations on the array :(

Answer 1

After some research, I was able to render the 1-bit per pixel image as a texture with the following code:
static GLubyte smiley[] = /* 16x16 smiley face */
{
0x03, 0xc0, /* **** */
0x0f, 0xf0, /* ******** */
0x1e, 0x78, /* **** **** */
0x39, 0x9c, /* *** ** *** */
0x77, 0xee, /* *** ****** *** */
0x6f, 0xf6, /* ** ******** ** */
0xff, 0xff, /* **************** */
0xff, 0xff, /* **************** */
0xff, 0xff, /* **************** */
0xff, 0xff, /* **************** */
0x73, 0xce, /* *** **** *** */
0x73, 0xce, /* *** **** *** */
0x3f, 0xfc, /* ************ */
0x1f, 0xf8, /* ********** */
0x0f, 0xf0, /* ******** */
0x03, 0xc0 /* **** */
};
float index[] = {0.0, 1.0};
glPixelStorei(GL_UNPACK_ALIGNMENT,1);
glPixelMapfv(GL_PIXEL_MAP_I_TO_R, 2, index);
glPixelMapfv(GL_PIXEL_MAP_I_TO_G, 2, index);
glPixelMapfv(GL_PIXEL_MAP_I_TO_B, 2, index);
glPixelMapfv(GL_PIXEL_MAP_I_TO_A, 2, index);
glTexImage2D(GL_TEXTURE_2D,0,GL_RGBA,16,16,0,GL_COLOR_INDEX,GL_BITMAP,smiley);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
and here is the result:

Answer 2

The smallest uncompressed texture-format for luminance images uses 8 bits per pixel.
However, 1 bit per pixel images can be compressed without loss to the S3TC or DXT format. This will still not be 1 bit per pixel but somewhere between 2 and 3 bits.
If you really need 1 bit per pixel you can do so with a little trick. Load 8 1 bit per pixel textures as one 8 bit Alpha-only texture (image 1 gets loaded into bit 1, image 2 into bit 2 and so on). Once you've done that you can "address" each of the sub-textures using the alpha-test feature and a bit of texture environment programming to turn alpha into a color.
This will of only work if you have 8 1 bit per pixel textures and tricky to get right though.