texture.c

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/* This code is (C) AllegroGL contributors, and double licensed under
 * the GPL and zlib licenses. See gpl.txt or zlib.txt for details.
 */
#include <string.h>

#include "alleggl.h"
#include "allglint.h"

#include <allegro/internal/aintern.h>

#ifdef ALLEGRO_MACOSX
#include <OpenGL/glu.h>
#else
#include <GL/glu.h>
#endif

static GLint allegro_gl_opengl_internal_texture_format = -1;
static int allegro_gl_use_mipmapping_for_textures = 0;
int __allegro_gl_use_alpha = FALSE;
int __allegro_gl_flip_texture = TRUE;
GLint __allegro_gl_texture_read_format[5];
GLint __allegro_gl_texture_components[5];

#define PREFIX_I                "agl-tex INFO: "
#define PREFIX_W                "agl-tex WARNING: "
#define PREFIX_E                "agl-tex ERROR: "


char const *__allegro_gl_get_format_description(GLint format)
{
    static char str[256];
#define F(s) case s: return #s
    switch (format) {
        F(GL_ALPHA);
        F(GL_ALPHA4);
        F(GL_ALPHA8);
        F(GL_ALPHA12);
        F(GL_ALPHA16);
        F(GL_ALPHA16F_ARB);
        F(GL_ALPHA32F_ARB);
        F(GL_INTENSITY);
        F(GL_INTENSITY4);
        F(GL_INTENSITY8);
        F(GL_INTENSITY12);
        F(GL_INTENSITY16);
        F(GL_INTENSITY16F_ARB);
        F(GL_INTENSITY32F_ARB);
        F(GL_LUMINANCE);
        F(GL_LUMINANCE4);
        F(GL_LUMINANCE8);
        F(GL_LUMINANCE12);
        F(GL_LUMINANCE16);
        F(GL_LUMINANCE16F_ARB);
        F(GL_LUMINANCE32F_ARB);
        F(GL_LUMINANCE_ALPHA);
        F(GL_LUMINANCE4_ALPHA4);
        F(GL_LUMINANCE12_ALPHA4);
        F(GL_LUMINANCE8_ALPHA8);
        F(GL_LUMINANCE6_ALPHA2);
        F(GL_LUMINANCE12_ALPHA12);
        F(GL_LUMINANCE16_ALPHA16);
        F(GL_LUMINANCE_ALPHA16F_ARB);
        F(GL_LUMINANCE_ALPHA32F_ARB);
        F(GL_RGB);
        F(GL_R3_G3_B2);
        F(GL_RGB4);
        F(GL_RGB5);
        F(GL_RGB8);
        F(GL_RGB10);
        F(GL_RGB12);
        F(GL_RGB16);
        F(GL_RGB16F_ARB);
        F(GL_RGB32F_ARB);
        F(GL_RGBA);
        F(GL_RGBA2);
        F(GL_RGBA4);
        F(GL_RGB5_A1);
        F(GL_RGBA8);
        F(GL_RGB10_A2);
        F(GL_RGBA12);
        F(GL_RGBA16);
        F(GL_RGBA16F_ARB);
        F(GL_RGBA32F_ARB);
    }
    uszprintf(str, sizeof str, "%x", format);
    return str;
#undef F
}



/* int __allegro_gl_get_num_channels(GLenum format) */
int __allegro_gl_get_num_channels(GLenum format) {
        
    switch (format) {
    case 1:
    case GL_ALPHA:
    case GL_ALPHA4:
    case GL_ALPHA8:
    case GL_ALPHA12:
    case GL_ALPHA16:
    case GL_ALPHA16F_ARB:
    case GL_ALPHA32F_ARB:
    case GL_INTENSITY:
    case GL_INTENSITY4:
    case GL_INTENSITY8:
    case GL_INTENSITY12:
    case GL_INTENSITY16:
    case GL_INTENSITY16F_ARB:
    case GL_INTENSITY32F_ARB:
    case GL_LUMINANCE:
    case GL_LUMINANCE4:
    case GL_LUMINANCE8:
    case GL_LUMINANCE12:
    case GL_LUMINANCE16:
    case GL_LUMINANCE16F_ARB:
    case GL_LUMINANCE32F_ARB:
        return 1;
    case 2:
    case GL_LUMINANCE_ALPHA:
    case GL_LUMINANCE4_ALPHA4:
    case GL_LUMINANCE12_ALPHA4:
    case GL_LUMINANCE8_ALPHA8:
    case GL_LUMINANCE6_ALPHA2:
    case GL_LUMINANCE12_ALPHA12:
    case GL_LUMINANCE16_ALPHA16:
    case GL_LUMINANCE_ALPHA16F_ARB:
    case GL_LUMINANCE_ALPHA32F_ARB:
        return 2;
    case 3:
    case GL_RGB:
    case GL_R3_G3_B2:
    case GL_RGB4:
    case GL_RGB5:
    case GL_RGB8:
    case GL_RGB10:
    case GL_RGB12:
    case GL_RGB16:
    case GL_RGB16F_ARB:
    case GL_RGB32F_ARB:
        return 3;
    case 4:
    case GL_RGBA:
    case GL_RGBA2:
    case GL_RGBA4:
    case GL_RGB5_A1:
    case GL_RGBA8:
    case GL_RGB10_A2:
    case GL_RGBA12:
    case GL_RGBA16:
    case GL_RGBA16F_ARB:
    case GL_RGBA32F_ARB:
        return 4;
    default:
        return 0;
    }
}



/* GLint __allegro_gl_get_texture_format_ex(BITMAP *bmp, int flags) */
GLint __allegro_gl_get_texture_format_ex(BITMAP *bmp, int flags) {

    if (!bmp) {
        return -1;
    }

    switch (bitmap_color_depth(bmp)) {
        case 32:
            if (flags
                 & (AGL_TEXTURE_HAS_ALPHA | AGL_TEXTURE_FORCE_ALPHA_INTERNAL)) {
                return GL_RGBA8;
            }
            else {
                return GL_RGB8;
            }
        case 8:
            return GL_INTENSITY8;
        case 15:
            if (flags & AGL_TEXTURE_FORCE_ALPHA_INTERNAL) {
                return GL_RGB5_A1;
            }
            else {
                return GL_RGB5;
            }
        case 16:
        case 24:
            if (flags & AGL_TEXTURE_FORCE_ALPHA_INTERNAL) {
                return GL_RGBA8;
            }
            else {
                return GL_RGB8;
            }
        default:
            return -1;
    }

    return -1;
}



/* GLint allegro_gl_get_texture_format(BITMAP *bmp) */
GLint allegro_gl_get_texture_format(BITMAP *bmp) {

    if (bmp && allegro_gl_opengl_internal_texture_format == -1) {
        return __allegro_gl_get_texture_format_ex(bmp,
                __allegro_gl_use_alpha ? AGL_TEXTURE_FORCE_ALPHA_INTERNAL : 0);
    }
    
    return allegro_gl_opengl_internal_texture_format;
}



/* GLint allegro_gl_set_texture_format(GLint format) */
GLint allegro_gl_set_texture_format(GLint format) {

    GLint old = allegro_gl_opengl_internal_texture_format;
    allegro_gl_opengl_internal_texture_format = format;
    return old;
}



/* GLenum __allegro_gl_get_bitmap_type(BITMAP *bmp, int flags) */
GLenum __allegro_gl_get_bitmap_type(BITMAP *bmp, int flags) {

    int c = bitmap_color_depth(bmp);

    switch (c) {

        case 8:
            return __allegro_gl_texture_read_format[0];

        case 15:
            return __allegro_gl_texture_read_format[1];

        case 16:
            return __allegro_gl_texture_read_format[2];

        case 24:
            return __allegro_gl_texture_read_format[3];

        case 32:
            return __allegro_gl_texture_read_format[4];
    
        default:
            TRACE(PREFIX_E "get_bitmap_type: unhandled bitmap depth: %d\n",
                  c);
            return -1;
    }
}



/* GLenum __allegro_gl_get_bitmap_color_format(BITMAP *bmp, int flags) */
GLenum __allegro_gl_get_bitmap_color_format(BITMAP *bmp, int flags) {

    int c = bitmap_color_depth(bmp);

    switch (c) {

        case 8:
            if (flags & AGL_TEXTURE_ALPHA_ONLY) {
                return GL_ALPHA;
            }
            else {
                return __allegro_gl_texture_components[0];
            }

        case 15:
            if (flags & AGL_TEXTURE_FORCE_ALPHA_INTERNAL) {
                return GL_RGBA;
            }
            else {
                return __allegro_gl_texture_components[1];
            }

        case 16:
            return __allegro_gl_texture_components[2];

        case 24:
            return __allegro_gl_texture_components[3];

        case 32:
            if (flags & (AGL_TEXTURE_HAS_ALPHA
                       | AGL_TEXTURE_FORCE_ALPHA_INTERNAL)) {
                return GL_RGBA;
            }
            else {
                return __allegro_gl_texture_components[4];
            }
    
        default:
            TRACE(PREFIX_E "get_bitmap_color_format: unhandled bitmap "
                  "depth: %d\n", c);
            return -1;
    }
}



/* int allegro_gl_use_mipmapping(int enable) */
int allegro_gl_use_mipmapping(int enable) {

    int old = allegro_gl_use_mipmapping_for_textures;
    allegro_gl_use_mipmapping_for_textures = enable;
    return old;
}
    


/* int allegro_gl_use_alpha_channel(int enable) */
int allegro_gl_use_alpha_channel(int enable) {

    int old = __allegro_gl_use_alpha;
    __allegro_gl_use_alpha = enable;
    return old;
}
    


/* int allegro_gl_flip_texture(int enable) */
int allegro_gl_flip_texture(int enable) {

    int old = __allegro_gl_flip_texture;
    __allegro_gl_flip_texture = enable;
    return old;
}
    


/* int allegro_gl_check_texture_ex(int flags, BITMAP *bmp, GLuint internal_format) */
int allegro_gl_check_texture_ex(int flags, BITMAP *bmp,
                                   GLint internal_format) {

    return (allegro_gl_make_texture_ex(flags | AGL_TEXTURE_CHECK_VALID_INTERNAL,
                                       bmp, internal_format) ? TRUE : FALSE);
}



/* Convert flags from pre-0.2.0 to 0.2.0+ */
static int __allegro_gl_convert_flags(int flags) {

    flags |= AGL_TEXTURE_RESCALE;

    if (allegro_gl_use_mipmapping_for_textures) {
        flags |= AGL_TEXTURE_MIPMAP;
    }
    if (__allegro_gl_use_alpha) {
        flags |= AGL_TEXTURE_HAS_ALPHA;
    }
    if (__allegro_gl_flip_texture) {
        flags |= AGL_TEXTURE_FLIP;
    }

    if (allegro_gl_opengl_internal_texture_format == GL_ALPHA4
     || allegro_gl_opengl_internal_texture_format == GL_ALPHA8
     || allegro_gl_opengl_internal_texture_format == GL_ALPHA12
     || allegro_gl_opengl_internal_texture_format == GL_ALPHA16
     || allegro_gl_opengl_internal_texture_format == GL_ALPHA
     || allegro_gl_opengl_internal_texture_format == GL_INTENSITY4
     || allegro_gl_opengl_internal_texture_format == GL_INTENSITY8
     || allegro_gl_opengl_internal_texture_format == GL_INTENSITY12
     || allegro_gl_opengl_internal_texture_format == GL_INTENSITY16
     || allegro_gl_opengl_internal_texture_format == GL_INTENSITY
     || allegro_gl_opengl_internal_texture_format == 1) {
        flags |= AGL_TEXTURE_ALPHA_ONLY;
    }

    return flags;
}



/* int allegro_gl_check_texture(BITMAP *bmp) */
int allegro_gl_check_texture(BITMAP *bmp) {

    int flags = __allegro_gl_convert_flags(0);
    
    return allegro_gl_check_texture_ex(flags, bmp,
                                     allegro_gl_opengl_internal_texture_format);
}



/* Integer log2 function. Not optimized for speed. */
static int log2i(int n) {
    
    int k;
    
    if (n < 1) {
        return -1;
    }

    k = 0;
    while (n >>= 1) {
        k++;
    }

    return k;
}



/* BITMAP *__allegro_gl_munge_bitmap(int flags, BITMAP *bmp, GLint *type, GLint *format) */
BITMAP *__allegro_gl_munge_bitmap(int flags, BITMAP *bmp, int x, int y,
                                  int w, int h, GLint *type, GLint *format) {
    
    BITMAP *ret = 0, *temp = 0;

    int need_rescale = 0;
    int need_alpha   = 0;
    int need_flip    = 0;
    int depth = bitmap_color_depth(bmp);
    int force_copy   = 0;

    const int old_w = w, old_h = h;

    if (flags & AGL_TEXTURE_RESCALE) {
        
        /* Check if rescaling is needed */

        /* NP2 is not supported, and the texture isn't a power-of-two.
         * Resize the next power of 2
         */     
        if (!allegro_gl_extensions_GL.ARB_texture_non_power_of_two
         && ((w & (w - 1)) || (h & (h - 1)))) {
            w = __allegro_gl_make_power_of_2(w);
            h = __allegro_gl_make_power_of_2(h);
            TRACE(PREFIX_I "munge_bitmap: Rescaling bitmap from "
                  "%ix%i to %ix%i due to non-power-of-2 source size.\n",
                  old_w, old_h, w, h);
            need_rescale = 1;
        }

        /* Don't go over the max texture size */
        if (w > allegro_gl_info.max_texture_size) {
            w = allegro_gl_info.max_texture_size;
            TRACE(PREFIX_I "munge_bitmap: Rescaling bitmap from "
                  "%ix%i to %ix%i due to max supported size exceed.\n",
                  old_w, old_h, w, h);
            need_rescale = 1;
        }
        
        if (h > allegro_gl_info.max_texture_size) {
            h = allegro_gl_info.max_texture_size;
            TRACE(PREFIX_I "munge_bitmap: Rescaling bitmap from "
                  "%ix%i to %ix%i due to max supported size exceed.\n",
                  old_w, old_h, w, h);
            need_rescale = 1;
        }

        /* Voodoos don't support mipmaps for textures greater than 32x32.
         * If we're allowed to rescale, rescale the bitmap to 32x32.
         * XXX <rohannessian> Apparently, this is a bug in one version
         * of the Voodoo GL driver. Need to figure out a workaround
         * for that.
         */
        if (allegro_gl_info.is_voodoo && (flags & AGL_TEXTURE_MIPMAP)
          && (w > 32 || h > 32)) {

            w = MIN(32, w);
            h = MIN(32, h);
            
            TRACE(PREFIX_I "munge_bitmap: Rescaling bitmap from "
                  "%ix%i to %ix%i due to Voodoo driver bug.\n",
                  old_w, old_h, w, h);
            need_rescale = 1;
        }
    }

    /* Matrox G200 cards have a bug where rectangular textures can't have
     * more than 4 levels of mipmaps (max_mip == 3). This doesn't seem
     * to affect square textures.
     *
     * Note: Using GLU to build the mipmaps seems to work. Maybe AGL is
     * doing something wrong?
     *
     * Workaround: Use GLU to build the mipmaps, and force depth to 24 or
     * 32.
     */
    if ( allegro_gl_info.is_matrox_g200 && (flags & AGL_TEXTURE_MIPMAP)) {
        int wl = log2i(w);
        int hl = log2i(h);

        if (w != h && MAX(wl, hl) > 3 && depth < 24
         && !(flags & AGL_TEXTURE_ALPHA_ONLY)) {
            TRACE(PREFIX_I "munge_bitmap: G200 path in use.\n");
            depth = 24;
        }
    }
    
    /* Do we need to flip the texture on the t axis? */
    if (flags & AGL_TEXTURE_FLIP) {
        need_flip = 1;
    }


    /* If not supported, blit to a 24 bpp bitmap and try again
     */
    if (*type == -1) {
        TRACE(PREFIX_W "munge_bitmap: using temporary 24bpp bitmap\n");
        depth = 24;
    }

    /* We need a texture that can be used for masked blits.
     * Insert an alpha channel if one is not there.
     * If it's already there, replace it by 0/1 as needed.
     */
    if ((flags & AGL_TEXTURE_MASKED) && !(flags & AGL_TEXTURE_ALPHA_ONLY)) {
        need_alpha = 1;

        switch (depth) {
        case 15:
            if (!allegro_gl_extensions_GL.EXT_packed_pixels) {
                depth = 32;
            }
            break;
        case 8:
        case 16:
        case 24:
        case 32:
            depth = 32;
            break;
        }
        force_copy = 1;
    }

    /* Allegro fills in 0 for the alpha channel. Matrox G200 seems to ignore
     * the internal format; so we need to drop down to 24-bpp if no alpha
     * will be needed.
     */
    if (allegro_gl_info.is_matrox_g200 && !(flags & AGL_TEXTURE_MASKED)
       && !(flags & AGL_TEXTURE_HAS_ALPHA) && depth == 32) {
        TRACE(PREFIX_I "munge_bitmap: G200 path in use.\n");
        depth = 24;
        force_copy = 1;
    }

    
    /* Do we need to do a color depth conversion or bitmap copy? */
    if (depth != bitmap_color_depth(bmp) || force_copy) {

        TRACE(PREFIX_I "munge_bitmap: Need to perform depth conversion from %i "
              "to %i bpp.\n", bitmap_color_depth(bmp), depth);

        temp = create_bitmap_ex(depth, bmp->w, bmp->h);

        if (!temp) {
            TRACE(PREFIX_E "munge_bitmap: Unable to create temporary bitmap "
                  "%ix%ix%i\n", bmp->w, bmp->h, depth);
            return NULL;
        }

        /* XXX <rohannessian> Use palette conversion?
         */
        if (bitmap_color_depth(bmp) == 8 && depth > 8) {
            int i, j;
            for (j = 0; j < bmp->h; j++) {
                for (i = 0; i < bmp->w; i++) {
                    int c = _getpixel(bmp, i, j);
                    putpixel(temp, i, j, makecol_depth(depth, c, c, c));
                }
            }
        }
        else {
            blit(bmp, temp, 0, 0, 0, 0, bmp->w, bmp->h);
        }
        bmp = temp;

        *format = __allegro_gl_get_bitmap_color_format(bmp, flags);
        *type = __allegro_gl_get_bitmap_type(bmp, flags);
    }



    /* Nothing to do? */
    if (!need_rescale && !need_alpha && !need_flip) {

        TRACE(PREFIX_I "munge_bitmap: No need for munging - returning %p\n",
              temp);
        
        /* Return depth-converte bitmap, if present */
        if (temp) {
            return temp;
        }
        return NULL;
    }

    ret = create_bitmap_ex(depth, w, h);
    
    if (!ret) {
        TRACE(PREFIX_E "munge_bitmap: Unable to create result bitmap "
              "%ix%ix%i\n", w, h, depth);
        goto error;
    }


    /* No need to fill in bitmap if we're just making a query */
    if (flags & AGL_TEXTURE_CHECK_VALID_INTERNAL) {
        if (temp) {
            destroy_bitmap(temp);
        }
        return ret;
    }


    /* Perform flip
     * I don't want to have to deal with *yet another* temporary bitmap
     * so instead, I fugde the line pointers around.
     * This will work because we require Allegro memory bitmaps anyway.
     */
    if (need_flip) {
        int i;
        TRACE(PREFIX_I "munge_bitmap: Flipping bitmap.\n");
        for (i = 0; i < bmp->h/2; i++) {
            unsigned char *l = bmp->line[i];
            bmp->line[i] = bmp->line[bmp->h - i - 1];
            bmp->line[bmp->h - i - 1] = l;
        }
    }
    
    /* Rescale bitmap */
    if (need_rescale) {
        TRACE(PREFIX_I "munge_bitmap: Rescaling bitmap.\n");
        stretch_blit(bmp, ret, x, y, old_w, old_h, 0, 0, ret->w, ret->h);
    }
    else {
        TRACE(PREFIX_I "munge_bitmap: Copying bitmap.\n");
        blit(bmp, ret, x, y, 0, 0, w, h);
    }

    /* Restore the original bitmap, if needed */
    if (need_flip && !temp) {
        int i;
        TRACE(PREFIX_I "munge_bitmap: Unflipping bitmap.\n");
        for (i = 0; i < bmp->h/2; i++) {
            unsigned char *l = bmp->line[i];
            bmp->line[i] = bmp->line[bmp->h - i - 1];
            bmp->line[bmp->h - i - 1] = l;
        }
    }
    
    /* Insert alpha channel */
    if (need_alpha) {
        int i, j;
        int mask = bitmap_mask_color(ret);

        /* alpha mask for 5.5.5.1 pixels */
        int alpha = (-1) ^ makecol_depth(depth, 255, 255, 255);

        TRACE(PREFIX_I "munge_bitmap: Inserting alpha channel.\n");

        for (j = 0; j < h; j++) {
            for (i = 0; i < w; i++) {
                int pix;
                
                switch (depth) {
                case 32:
                    pix = _getpixel32(ret, i, j);

                    if (pix == mask) {
                        pix = 0;
                    }
                    else if ((flags & AGL_TEXTURE_HAS_ALPHA) == 0) {
                        int r, g, b;
                        r = getr32(pix);
                        g = getg32(pix);
                        b = getb32(pix);
                        pix = makeacol32(r, g, b, 255);
                    }
                    _putpixel32(ret, i, j, pix);
                    break;
                case 15: 
                    pix = _getpixel16(ret, i, j);

                    if (pix == mask) {
                        pix = 0;
                    }
                    else {
                        pix |= alpha;
                    }
                    
                    _putpixel16(temp, i, j, pix);
                    break;
                default:
                    /* Shouldn't actually come here */
                    ASSERT(0);
                }
            }
        }
    }


error:
    if (temp) {
        destroy_bitmap(temp);
    }

    return ret;
}



/* Perform the actual texture upload. Helper for agl_make_texture_ex().
 */
static GLuint do_texture_upload(BITMAP *bmp, GLuint tex, GLint internal_format,
                              GLint format, GLint type, int flags) {

    int bytes_per_pixel = BYTES_PER_PIXEL(bitmap_color_depth(bmp));
    GLint saved_row_length;
    GLint saved_alignment;
    GLenum target = GL_TEXTURE_2D;

    glBindTexture(target, tex);
    

    /* Handle proxy texture checks */
    if (flags & AGL_TEXTURE_CHECK_VALID_INTERNAL) { 
        /* <bcoconni> allegro_gl_check_texture is broken with GL drivers based
         *  on Mesa. It seems this is a Mesa bug...
         */
        if (allegro_gl_info.is_mesa_driver) {
            AGL_LOG(1, "* Note * check_texture: Mesa driver detected: "
                   "PROXY_TEXTURE_2D tests are skipped\n");
            return tex;
        }
        else {
            glTexImage2D(GL_PROXY_TEXTURE_2D, 0, internal_format,
                         bmp->w, bmp->h, 0, format, type, NULL);

            glGetTexLevelParameteriv(GL_PROXY_TEXTURE_2D, 0,
                                     GL_TEXTURE_COMPONENTS, &internal_format);

            return (internal_format ? tex : 0);
        }
    }
    

    /* Set up pixel transfer mode */
    glGetIntegerv(GL_UNPACK_ROW_LENGTH, &saved_row_length);
    glGetIntegerv(GL_UNPACK_ALIGNMENT,  &saved_alignment);
    glPixelStorei(GL_UNPACK_ALIGNMENT, 1);

    TRACE(PREFIX_I "do_texture_upload: Making texture: bpp: %i\n",
          bitmap_color_depth(bmp));

    /* Generate mipmaps, if needed */
    if (flags & AGL_TEXTURE_MIPMAP) {
        
        if (allegro_gl_extensions_GL.SGIS_generate_mipmap) {
            /* Easy way out - let the driver do it ;) 
             * We do need to set high-qual mipmap generation though.
             */
            glHint(GL_GENERATE_MIPMAP_HINT, GL_NICEST);
            glTexParameteri(target, GL_GENERATE_MIPMAP, GL_TRUE);
            TRACE(PREFIX_I "do_texture_upload: Using SGIS_generate_mipmap for "
                  "mipmap generation.\n");
        }
        else if (allegro_gl_info.is_matrox_g200
             && (flags & AGL_TEXTURE_MIPMAP) && (bitmap_color_depth(bmp) >= 24
                || bitmap_color_depth(bmp) == 8)
             && (bmp->w != bmp->h)) {
                
            /* Matrox G200 has issues with our mipmapping code. Use GLU if we
             * can.
             */
            TRACE(PREFIX_I "do_texture_upload: Using GLU for mipmaps.\n");
            glPixelStorei(GL_UNPACK_ROW_LENGTH, bmp->h > 1
                        ? (bmp->line[1] - bmp->line[0]) / bytes_per_pixel
                        : bmp->w);
            glPixelStorei(GL_UNPACK_ROW_LENGTH,
                               (bmp->line[1] - bmp->line[0]) / bytes_per_pixel);
            gluBuild2DMipmaps(GL_TEXTURE_2D, internal_format, bmp->w, bmp->h,
                              format, type, bmp->line[0]);
        }
        else {
            int w = bmp->w;
            int h = bmp->h;
            int depth = bitmap_color_depth(bmp);
            
            /* The driver can't generate mipmaps for us. We can't rely on GLU
             * since the Win32 version doesn't support any of the new pixel
             * formats. Instead, we'll use our own downsampler (which only
             * has to work on Allegro BITMAPs)
             */
            BITMAP *temp = create_bitmap_ex(depth, w / 2, h / 2);

            /* We need to generate mipmaps up to 1x1 - compute the number
             * of levels we need.
             */
            int num_levels = log2i(MAX(bmp->w, bmp->h));
            
            int i, x, y;

            BITMAP *src, *dest;

            TRACE(PREFIX_I "do_texture_upload: Using Allegro for "
                  "mipmap generation.\n");

            if (!temp) {
                TRACE(PREFIX_E "do_texture_upload: Unable to create "
                      "temporary bitmap sized %ix%ix%i for mipmap generation!",
                      w / 2, h / 2, depth);
                tex = 0;
                goto end;
            }

            src = bmp;
            dest = temp;
            
            for (i = 1; i <= num_levels; i++) {

                for (y = 0; y < h; y += 2) {
                    for (x = 0; x < w; x += 2) {

                        int r, g, b, a;
                        int pix[4];
                        int avg;
                        
                        pix[0] = getpixel(src, x,     y);
                        pix[1] = getpixel(src, x + 1, y);
                        pix[2] = getpixel(src, x,     y + 1);
                        pix[3] = getpixel(src, x + 1, y + 1);

                        if (w == 1) {
                            pix[1] = pix[0];
                            pix[3] = pix[2];
                        }
                        if (h == 1) {
                            pix[2] = pix[0];
                            pix[3] = pix[1];
                        }

                        if (flags & AGL_TEXTURE_ALPHA_ONLY) {
                            avg = (pix[0] + pix[1] + pix[2] + pix[3] + 2) / 4;
                        }
                        else {
                            r = (getr_depth(depth, pix[0])
                               + getr_depth(depth, pix[1])
                               + getr_depth(depth, pix[2])
                               + getr_depth(depth, pix[3]) + 2) / 4;
                            g = (getg_depth(depth, pix[0])
                               + getg_depth(depth, pix[1])
                               + getg_depth(depth, pix[2])
                               + getg_depth(depth, pix[3]) + 2) / 4;
                            b = (getb_depth(depth, pix[0])
                               + getb_depth(depth, pix[1])
                               + getb_depth(depth, pix[2])
                               + getb_depth(depth, pix[3]) + 2) / 4;
                            a = (geta_depth(depth, pix[0])
                               + geta_depth(depth, pix[1])
                               + geta_depth(depth, pix[2])
                               + geta_depth(depth, pix[3]) + 2) / 4;

                            avg = makeacol_depth(depth, r, g, b, a);
                        }

                        putpixel(dest, x / 2, y / 2, avg);
                    }
                }
                src = temp;

                /* Note - we round down; we're still compatible with
                 * ARB_texture_non_power_of_two.
                 */
                w = MAX(w / 2, 1);
                h = MAX(h / 2, 1);

                TRACE(PREFIX_I "do_texture_upload: Unpack row length: %li.\n",
                      (temp->h > 1)
                     ? (long int)((temp->line[1] - temp->line[0]) / bytes_per_pixel)
                     : temp->w);

                glPixelStorei(GL_UNPACK_ROW_LENGTH, temp->h > 1
                             ? (temp->line[1] - temp->line[0]) / bytes_per_pixel
                             : temp->w);    

                glTexImage2D(GL_TEXTURE_2D, i, internal_format,
                             w, h, 0, format, type, temp->line[0]);

                TRACE(PREFIX_I "do_texture_upload: Mipmap level: %i, "
                      "size: %i x %i\n", i, w, h);

                TRACE(PREFIX_I "do_texture_upload: Uploaded texture: level %i, "
                      "internalformat: %s, %ix%i, format: 0x%x, type: 0x%x."
                      "\n", i, __allegro_gl_get_format_description(internal_format),
                      bmp->w, bmp->h, format, type);
            }

            destroy_bitmap(temp);
        }
    }

    glPixelStorei(GL_UNPACK_ROW_LENGTH, (bmp->h > 1)
                 ? (bmp->line[1] - bmp->line[0]) / bytes_per_pixel
                 : bmp->w);
    
    TRACE(PREFIX_I "do_texture_upload: Unpack row length: %li.\n",
      (bmp->h > 1) ? (long int)((bmp->line[1] - bmp->line[0]) / bytes_per_pixel)
                   : bmp->w);

    /* Upload the base texture */
    glGetError();
    glTexImage2D(GL_TEXTURE_2D, 0, internal_format,
                 bmp->w, bmp->h, 0, format, type, bmp->line[0]);

    TRACE(PREFIX_I "do_texture_upload: Uploaded texture: level 0, "
          "internalformat: %s, %ix%i, format: 0x%x, type: 0x%x.\n",
          __allegro_gl_get_format_description(internal_format),
          bmp->w, bmp->h, format, type);
    
    TRACE(PREFIX_I "do_texture_upload: GL Error code: 0x%x\n", glGetError());

    if (!(flags & AGL_TEXTURE_MIPMAP)) {
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    }
    
end:
    /* Restore state */
    glPixelStorei(GL_UNPACK_ROW_LENGTH, saved_row_length);
    glPixelStorei(GL_UNPACK_ALIGNMENT,  saved_alignment);

    return tex;
}   



/* GLuint allegro_gl_make_texture_ex(int flag, BITMAP *bmp, GLint internal_format) */
GLuint allegro_gl_make_texture_ex(int flags, BITMAP *bmp, GLint internal_format)
{
    GLuint tex = 0, ret = 0;
    BITMAP *temp = NULL;
    GLint type;
    GLint format;
    GLint old_tex;

    /* Print the parameters */
#ifdef DEBUGMODE
    char buf[1024] = "";
#   define PFLAG(name) if (flags & name) strcat(buf, #name "|");
    PFLAG(AGL_TEXTURE_MIPMAP);
    PFLAG(AGL_TEXTURE_HAS_ALPHA);
    PFLAG(AGL_TEXTURE_FLIP);
    PFLAG(AGL_TEXTURE_MASKED);
    PFLAG(AGL_TEXTURE_RESCALE);
    PFLAG(AGL_TEXTURE_ALPHA_ONLY);
#   undef PFLAG

    TRACE(PREFIX_I "make_texture_ex: flags: %s, bitmap %ix%i, %i bpp.\n", buf,
          bmp ? bmp->w : 0, bmp ? bmp->h : 0,
          bmp ? bitmap_color_depth(bmp) : 0);
    if (internal_format == -1) {
        TRACE(PREFIX_I "internalformat: AUTO\n");
    }
    else {
        TRACE(PREFIX_I "internalformat: %s\n",
            __allegro_gl_get_format_description(internal_format));
    }
#endif  

    /* Basic parameter checks */
    if (!__allegro_gl_valid_context)
        return 0;

    if (!bmp) {
        return 0;
    }

    glGetIntegerv(GL_TEXTURE_2D_BINDING, &old_tex);

    /* Voodoo cards don't seem to support mipmaps for textures over 32x32...
     */
    if ((bmp->w > 32 || bmp->h > 32) && (allegro_gl_info.is_voodoo)) {
        /* Disable mipmapping if the user didn't allow us to rescale */
        if (!(flags & AGL_TEXTURE_RESCALE)) {
            TRACE(PREFIX_I "make_texture_ex: Voodoo card detected && texture "
                  "size > 32 texels && no rescaling. Disabling mipmaps.\n");
            flags &= ~AGL_TEXTURE_MIPMAP;
        }
    }

    /* Check the maximum texture size */
    if (bmp->w > allegro_gl_info.max_texture_size
     || bmp->h > allegro_gl_info.max_texture_size) {
        if ((flags & AGL_TEXTURE_RESCALE) == 0) {
            TRACE(PREFIX_I "make_texture_ex: Max texture size exceeded but no "
                  "rescaling allowed. Returning 0 (unsupported).\n");
            return 0;
        }
    }

    /* Check power-of-2 */
    if (((bmp->w & (bmp->w - 1)) || (bmp->h & (bmp->h - 1)))
      && !(flags & AGL_TEXTURE_RESCALE)
      && !allegro_gl_extensions_GL.ARB_texture_non_power_of_two) {
        TRACE(PREFIX_I "make_texture_ex: Non-power-of-2 sized bitmap provided, "
              "no rescaling allowed, and ARB_texture_non_power_of_two "
              "unsupported. Returning 0 (unsupported).\n");
        return 0;
    }
    
    
    /* Get OpenGL format and type for this pixel data */
    format = __allegro_gl_get_bitmap_color_format(bmp, flags);
    type = __allegro_gl_get_bitmap_type(bmp, flags);
    
    if (flags & AGL_TEXTURE_ALPHA_ONLY) {
        type   = GL_UNSIGNED_BYTE;
        if (internal_format == GL_ALPHA || internal_format == GL_ALPHA4
         || internal_format == GL_ALPHA8) {
            format = GL_ALPHA;
        }
        else if (internal_format == GL_INTENSITY
              || internal_format == GL_INTENSITY4
              || internal_format == GL_INTENSITY8) {
            format = GL_RED;
        }
        else if (internal_format == GL_LUMINANCE
              || internal_format == GL_LUMINANCE4
              || internal_format == GL_LUMINANCE8) {
            format = GL_LUMINANCE;
        }

        /* Alpha bitmaps must be 8-bpp */
        if (bitmap_color_depth(bmp) != 8) {
            return 0;
        }
    }

    if (flags & AGL_TEXTURE_MASKED) {
        flags |= AGL_TEXTURE_FORCE_ALPHA_INTERNAL;
    }

    TRACE(PREFIX_I "make_texture_ex: Preselected texture format: %s, "
          "type: 0x%x\n", __allegro_gl_get_format_description(format), type);
    
    /* Munge the bitmap if needed (rescaling, alpha channel, etc) */
    temp = __allegro_gl_munge_bitmap(flags, bmp, 0, 0, bmp->w, bmp->h,
                                     &type, &format);
    if (temp) {
        bmp = temp;
    }
    
    if (internal_format == -1) {
        internal_format = __allegro_gl_get_texture_format_ex(bmp, flags);
        TRACE(PREFIX_I "make_texture_ex: Picked internalformat: %s\n",
              __allegro_gl_get_format_description(internal_format));
    }

    if (internal_format == -1) {
        TRACE(PREFIX_E "make_texture_ex: Invalid internal format!: "
              "%s\n", __allegro_gl_get_format_description(internal_format));
        goto end;
    }
    
    TRACE(PREFIX_I "make_texture_ex: dest format=%s, source format=%s, "
          "type=0x%x\n", __allegro_gl_get_format_description(internal_format),
              __allegro_gl_get_format_description(format), (int)type);

    
    /* ATI Radeon 7000 inverts R and B components when generating mipmaps and
     * the internal format is GL_RGB8, but only on mipmaps. Instead, we'll use
     * GL_RGBA8. This works for bitmaps of depth <= 24. For 32-bpp bitmaps,
     * some additional tricks are needed: We must fill in alpha with 255.
     */
    if (allegro_gl_info.is_ati_radeon_7000 && (flags & AGL_TEXTURE_MIPMAP)
     && internal_format == GL_RGB8
     && allegro_gl_extensions_GL.SGIS_generate_mipmap) {

        int i, j;
        int depth = bitmap_color_depth(bmp);

        TRACE(PREFIX_I "make_texture_ex: ATI Radeon 7000 detected, mipmapping "
              "used, SGIS_generate_mipmap available and selected "
              "internalformat is GL_RGB8 but format is GL_RGBA. Working around "
              "ATI driver bug by upgrading bitmap to 32-bpp and using GL_RGBA8 "
              "instead.\n");

        if (depth == 32) {

            /* Create temp bitmap if not already there */
            if (!temp) {
                temp = create_bitmap_ex(depth, bmp->w, bmp->h);
                if (!temp) {
                    TRACE(PREFIX_E "make_texture_ex: Unable to allocate "
                          "memory for temporary bitmap (Radeon 7000 path)!\n");
                    goto end;
                }
                blit(bmp, temp, 0, 0, 0, 0, bmp->w, bmp->h);
                bmp = temp;
            }
            
            /* Slow path, until ATI finally gets around to fixing their
             * drivers.
             *
             * Note: If destination internal format was GL_RGBx, then no masking
             * code is needed.
             */
            for (j = 0; j < bmp->h; j++) {
                for (i = 0; i < bmp->w; i++) {
                    int pix = _getpixel32(bmp, i, j);
                    _putpixel32(bmp, i, j,
                        makeacol32(getr32(pix), getg32(pix), getb32(pix), 255));
                }
            }
        }
        internal_format = GL_RGBA8;
    }
    

    /* Generate the texture */
    glGenTextures(1, &tex);
    if (!tex) {
        TRACE(PREFIX_E "make_texture_ex: Unable to create GL texture!\n");
        goto end;
    }

    ret = do_texture_upload(bmp, tex, internal_format, format, type, flags);

end:
    if (temp) {
        destroy_bitmap(temp);
    }

    if (!ret && tex) {
        glDeleteTextures(1, &tex);
    }

    glBindTexture(GL_TEXTURE_2D, old_tex);

    return tex;
}





/* GLuint allegro_gl_make_texture(BITMAP *bmp) */
GLuint allegro_gl_make_texture(BITMAP *bmp) {
        
    int flags = __allegro_gl_convert_flags(0);
    
    return allegro_gl_make_texture_ex(flags, bmp,
                                     allegro_gl_opengl_internal_texture_format);
}



/* GLuint allegro_gl_make_masked_texture(BITMAP *bmp) */
GLuint allegro_gl_make_masked_texture(BITMAP *bmp) {
        
    int flags = __allegro_gl_convert_flags(AGL_TEXTURE_MASKED);

    return allegro_gl_make_texture_ex(flags, bmp,
                                     allegro_gl_opengl_internal_texture_format);
}



/* GLenum allegro_gl_get_bitmap_type(BITMAP *bmp) */
GLenum allegro_gl_get_bitmap_type(BITMAP *bmp) {

    int flags = __allegro_gl_convert_flags(0);
    return __allegro_gl_get_bitmap_type(bmp, flags);
}



/* GLenum allegro_gl_get_bitmap_color_format(BITMAP *bmp) */
GLenum allegro_gl_get_bitmap_color_format(BITMAP *bmp) {

    int flags = __allegro_gl_convert_flags(0);
    return __allegro_gl_get_bitmap_color_format(bmp, flags);
}

---