videovtb.c

Go to the documentation of this file.

/* 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 <limits.h>

#include <allegro.h>

#ifdef ALLEGRO_WINDOWS
#include <winalleg.h>
#endif

#include "alleggl.h"
#include "allglint.h"
#include "glvtable.h"
#include <allegro/internal/aintern.h>
#ifdef ALLEGRO_MACOSX
#include <OpenGL/glu.h>
#else
#include <GL/glu.h>
#endif


#define MASKED_BLIT 1
#define BLIT        2
#define TRANS       3


static GFX_VTABLE allegro_gl_video_vtable;

/* Counter for video bitmaps. screen = 1 */
static int video_bitmap_count = 2;

static int __allegro_gl_video_bitmap_bpp = -1;

extern BITMAP *__agl_drawing_pattern_bmp;
BITMAP *old_pattern = NULL;

void allegro_gl_destroy_video_bitmap(BITMAP *bmp);



static int allegro_gl_make_video_bitmap_helper1(int w, int h, int x, int y,
                                   GLint target, AGL_VIDEO_BITMAP **pvid) {

    int internal_format;
    int bpp;

    if (__allegro_gl_video_bitmap_bpp == -1) {
        bpp = bitmap_color_depth(screen);
    }
    else {
        bpp = __allegro_gl_video_bitmap_bpp;
    }

    (*pvid) = malloc(sizeof(AGL_VIDEO_BITMAP));

    if (!(*pvid))
        return -1;

    memset(*pvid, 0, sizeof(AGL_VIDEO_BITMAP));

    /* Create associated bitmap */
    (*pvid)->memory_copy = create_bitmap_ex(bpp, w, h);
    if (!(*pvid)->memory_copy)
        return -1;
    
    (*pvid)->format = __allegro_gl_get_bitmap_color_format((*pvid)->memory_copy, AGL_TEXTURE_HAS_ALPHA);
    (*pvid)->type = __allegro_gl_get_bitmap_type((*pvid)->memory_copy, 0);
    internal_format = __allegro_gl_get_texture_format_ex((*pvid)->memory_copy, AGL_TEXTURE_HAS_ALPHA);

    (*pvid)->target = target;

    /* Fill in some values in the bitmap to make it act as a subbitmap
     */
    (*pvid)->width  = w;
    (*pvid)->height = h;
    (*pvid)->x_ofs = x;
    (*pvid)->y_ofs = y;

    /* Make a texture out of it */
    glGenTextures(1, &((*pvid)->tex));
    if (!((*pvid)->tex))
        return -1;

    glEnable((*pvid)->target);
    glBindTexture((*pvid)->target, ((*pvid)->tex));

    glTexImage2D((*pvid)->target, 0, internal_format, w, h,
                 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL);

    /* By default, use the Allegro filtering mode - ie: Nearest */
    glTexParameteri((*pvid)->target, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
    glTexParameteri((*pvid)->target, GL_TEXTURE_MAG_FILTER, GL_NEAREST);

    /* <mmimica>
       Clamping removed because we want video bitmaps that are set for
       patterned drawing to be GL_REPEAT (default wrapping mode). Doesn't
       seem to break anything.
    */
#if 0
    /* Clamp to edge */
    {
        GLenum clamp = GL_CLAMP_TO_EDGE;
        if (!allegro_gl_extensions_GL.SGIS_texture_edge_clamp) {
            clamp = GL_CLAMP;
        }
        glTexParameteri((*pvid)->target, GL_TEXTURE_WRAP_S, clamp);
        glTexParameteri((*pvid)->target, GL_TEXTURE_WRAP_T, clamp);
    }
#endif

    glDisable((*pvid)->target);

    if (allegro_gl_extensions_GL.EXT_framebuffer_object) {
        glGenFramebuffersEXT(1, &((*pvid)->fbo));
        if (!(*pvid)->fbo) {
            glDeleteTextures(1, &((*pvid)->tex));
            return -1;
        }

        glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, (*pvid)->fbo);
        glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT0_EXT, (*pvid)->target, (*pvid)->tex, 0);
        if (glCheckFramebufferStatusEXT(GL_FRAMEBUFFER_EXT) != GL_FRAMEBUFFER_COMPLETE_EXT) {
            /* Some FBO implementation limitation was hit, will use normal textures. */
            glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);
            glDeleteFramebuffersEXT(1, &((*pvid)->fbo));
            (*pvid)->fbo = 0;
            return 0;
        }
        
        glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);
    }
    else {
        (*pvid)->fbo = 0;
    }

    return 0;
}



static int allegro_gl_make_video_bitmap_helper0(int w, int h, int x, int y,
                                                AGL_VIDEO_BITMAP **pvid) {
        
    int is_power_of_2 = (!(w & (w - 1)) && !(h & (h - 1)));
    int texture_rect_available = allegro_gl_extensions_GL.ARB_texture_rectangle
#ifdef ALLEGRO_MACOSX
                             || allegro_gl_extensions_GL.EXT_texture_rectangle
#endif
                             || allegro_gl_extensions_GL.NV_texture_rectangle;
    GLint max_rect_texture_size = 0;

    if (texture_rect_available) {
        glGetIntegerv(GL_MAX_RECTANGLE_TEXTURE_SIZE_ARB, &max_rect_texture_size);
    }

    if (w <= allegro_gl_info.max_texture_size &&
        h <= allegro_gl_info.max_texture_size) {
        if (allegro_gl_extensions_GL.ARB_texture_non_power_of_two ||
            is_power_of_2) {
            if (allegro_gl_make_video_bitmap_helper1(w, h, x, y,
                                            GL_TEXTURE_2D, pvid)) {
                return -1;
            }
        }
        else if (texture_rect_available &&
                 w <= max_rect_texture_size &&
                 h <= max_rect_texture_size) {
            if (allegro_gl_make_video_bitmap_helper1(w, h, x, y,
                                            GL_TEXTURE_RECTANGLE_ARB, pvid)) {
                return -1;
            }
        }
        else {
            /* NPO2 textures are not suppored by the driver in any way.
             * Split the bitmap into smaller POT bitmaps. */
            const unsigned int BITS = sizeof(int) * CHAR_BIT;
            unsigned int i, j;
            unsigned int w1, h1;
            unsigned int x1, y1;
            unsigned int p1, p2;

            /* Find the POTs using bits. */
            y1 = 0;
            for (i = 0; i < BITS; i++) {
                p1 = 1 << i;
                if (h & p1)
                    h1 = p1;
                else
                    continue;

                x1 = 0;
                for (j = 0; j < BITS; j++) {
                    p2 = 1 << j;
                    if (w & p2)
                        w1 = p2;
                    else
                        continue;

                    if (allegro_gl_make_video_bitmap_helper0(w1, h1, x + x1,
                                                        y + y1, pvid)) {
                        return -1;
                    }
                    do {
                        pvid = &((*pvid)->next);
                    } while (*pvid);

                    x1 += w1;
                }

                y1 += h1;
            }
        }
    }
    else {
        /* Texture is too big to fit. Split it in 4 and try again. */
        int w1, w2, h1, h2;

        w2 = w / 2;
        w1 = w - w2;

        h2 = h / 2;
        h1 = h - h2;

        /* Even a 1x1 texture didn't work? Bail*/
        if (!w2 && !h2) {
            return -1;
        }

        /* Top-left corner */
        if (allegro_gl_make_video_bitmap_helper0(w1, h1, x, y, pvid)) {
            return -1;
        }
        do {
            pvid = &((*pvid)->next);
        } while (*pvid);

        /* Top-right corner */
        if (w2) {
            if (allegro_gl_make_video_bitmap_helper0(w2, h1, x + w1, y, pvid)) {
                return -1;
            }
            do {
                pvid = &((*pvid)->next);
            } while (*pvid);
        }
        /* Bottom-left corner */
        if (h2) {
            if (allegro_gl_make_video_bitmap_helper0(w1, h2, x, y + h1, pvid)) {
                return -1;
            }
            do {
                pvid = &((*pvid)->next);
            } while (*pvid);
        }
        /* Bottom-right corner */
        if (w2 && h2) {
            if (allegro_gl_make_video_bitmap_helper0(w2, h2, x + w1, y + h1, pvid)) {
                return -1;
            }
            do {
                pvid = &((*pvid)->next);
            } while (*pvid);
        }
    }

    return 0;
}



/* Will make a (potentially piece-wise) texture out of the specified bitmap
 * Source -must- be a memory bitmap or memory subbitmap (created by Allegro
 * only).
 *
 */
static BITMAP *allegro_gl_make_video_bitmap(BITMAP *bmp) {
    
    /* Grab a pointer to the bitmap data to patch */
    void *ptr = &bmp->extra;
    AGL_VIDEO_BITMAP **pvid = (AGL_VIDEO_BITMAP**)ptr;
    
    /* Convert bitmap to texture */
    if (allegro_gl_make_video_bitmap_helper0(bmp->w, bmp->h, 0, 0, pvid)) {
        goto agl_error;
    }

    return bmp;
    
agl_error:
    allegro_gl_destroy_video_bitmap(bmp);
    return NULL;
}



/* void allegro_gl_destroy_video_bitmap(BITMAP *bmp) */
void allegro_gl_destroy_video_bitmap(BITMAP *bmp) {

    AGL_VIDEO_BITMAP *vid = bmp ? bmp->extra : NULL, *next;
    
    if (!bmp)
        return;
    
    while (vid) {
        if (vid->memory_copy)
            destroy_bitmap(vid->memory_copy);
    
        if (vid->tex)
            glDeleteTextures(1, &vid->tex);

        if (vid->fbo)
            glDeleteFramebuffersEXT(1, &vid->fbo);
                                
        next = vid->next;
        free(vid);
        vid = next;
    }

    free(bmp->vtable);
    free(bmp);
    
    return;
}



/* BITMAP *allegro_gl_create_video_bitmap(int w, int h) */
BITMAP *allegro_gl_create_video_bitmap(int w, int h) {
    GFX_VTABLE *vtable;
    BITMAP *bitmap;

    bitmap = malloc(sizeof(BITMAP) + sizeof(char *));
    
    if (!bitmap)
        return NULL;

    bitmap->dat = NULL;
    bitmap->w = bitmap->cr = w;
    bitmap->h = bitmap->cb = h;
    bitmap->clip = TRUE;
    bitmap->cl = bitmap->ct = 0;
    bitmap->write_bank = bitmap->read_bank = NULL;
    /* We should keep tracks of allocated bitmaps for the ref counter */
    bitmap->id = BMP_ID_VIDEO | video_bitmap_count;
    bitmap->extra = NULL;
    bitmap->x_ofs = 0;
    bitmap->y_ofs = 0;
    bitmap->seg = _default_ds();
    bitmap->line[0] = NULL;
    bitmap->vtable = NULL;

    if (!allegro_gl_make_video_bitmap(bitmap)) {
        return NULL;
    }
    video_bitmap_count++;
    
    /* XXX <rohannessian> We ought to leave the Allegro values intact
     * Avoids bad interaction with correct Allegro programs.
     */
    vtable = malloc(sizeof(struct GFX_VTABLE));
    *vtable = allegro_gl_video_vtable;
    if (__allegro_gl_video_bitmap_bpp == -1) {
        vtable->color_depth = bitmap_color_depth(screen);
    }
    else {
        vtable->color_depth = __allegro_gl_video_bitmap_bpp;
    }
    switch (vtable->color_depth) {
        case 8:
            vtable->mask_color = MASK_COLOR_8;
        break;
        case 15:
            vtable->mask_color = MASK_COLOR_15;
        break;
        case 16:
            vtable->mask_color = MASK_COLOR_16;
        break;
        case 24:
            vtable->mask_color = MASK_COLOR_24;
        break;
        case 32:
            vtable->mask_color = MASK_COLOR_32;
        break;
    }
    bitmap->vtable = vtable;

    return bitmap;
}



/* allegro_gl_set_video_bitmap_color_depth(int bpp) */
GLint allegro_gl_set_video_bitmap_color_depth(int bpp) {
    GLint old_val = __allegro_gl_video_bitmap_bpp;
    __allegro_gl_video_bitmap_bpp = bpp;
    return old_val;
}


/* static void allegro_gl_video_acquire(struct BITMAP *bmp) */
static void allegro_gl_video_acquire(struct BITMAP *bmp) {}



/* static void allegro_gl_video_release(struct BITMAP *bmp) */
static void allegro_gl_video_release(struct BITMAP *bmp) {}



static void set_drawing_pattern(void)
{
    if (_drawing_pattern && !is_memory_bitmap(_drawing_pattern)) {
        old_pattern = _drawing_pattern;
        drawing_mode(_drawing_mode, __agl_drawing_pattern_bmp,
                     _drawing_x_anchor, _drawing_y_anchor);
    }
}



static void unset_drawing_pattern(void)
{
    if (old_pattern) {
        drawing_mode(_drawing_mode, old_pattern,
                     _drawing_x_anchor, _drawing_y_anchor);
        old_pattern = NULL;
    }
}



static int allegro_gl_video_getpixel(struct BITMAP *bmp, int x, int y)
{
    int pix = -1;
    AGL_VIDEO_BITMAP *vid;
    AGL_LOG(2, "glvtable.c:allegro_gl_screen_getpixel\n");  
    
    if (is_sub_bitmap(bmp)) {
        x += bmp->x_ofs;
        y += bmp->y_ofs;
    }
    if (x < bmp->cl || x >= bmp->cr || y < bmp->ct || y >= bmp->cb) {
        return -1;
    }

    vid = bmp->extra;
    
    while (vid) {
        if (vid->x_ofs <= x && vid->y_ofs <= y
         && vid->x_ofs + vid->memory_copy->w > x
         && vid->y_ofs + vid->memory_copy->h > y) {
            
            pix = getpixel(vid->memory_copy, x - vid->x_ofs, y - vid->y_ofs);
            break;
        }
        vid = vid->next;
    }
    
    if (pix != -1) {
        return pix;
    }
    
    return -1;
}



static void update_texture_memory(AGL_VIDEO_BITMAP *vid, int x1, int y1,
                                  int x2, int y2) {
    GLint saved_row_length;
    GLint saved_alignment;
    GLint type;
    GLint format;
    int bpp;
    BITMAP *temp = NULL;
    BITMAP *vbmp = vid->memory_copy;;

    glGetIntegerv(GL_UNPACK_ROW_LENGTH, &saved_row_length);
    glGetIntegerv(GL_UNPACK_ALIGNMENT, &saved_alignment);

    bpp = BYTES_PER_PIXEL(bitmap_color_depth(vid->memory_copy));
    format = vid->format;
    type = vid->type;

    glColor4ub(255, 255, 255, 255);

    /* If packed pixels (or GL 1.2) isn't supported, then we need to convert
     * the bitmap into something GL can understand - 24-bpp should do it.
     */
    if (!allegro_gl_extensions_GL.EXT_packed_pixels
                                          && bitmap_color_depth(vbmp) < 24) {
        temp = create_bitmap_ex(24, vbmp->w, vbmp->h);
        if (!temp)
            return;

        blit(vbmp, temp, 0, 0, 0, 0, temp->w, temp->h);
        vbmp = temp;
        bpp = BYTES_PER_PIXEL(bitmap_color_depth(vbmp));
        format = __allegro_gl_get_bitmap_color_format(vbmp, 0);
        type = __allegro_gl_get_bitmap_type(vbmp, 0);
    }

    glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
    glPixelStorei(GL_UNPACK_ROW_LENGTH,
                  vbmp->h > 1
                 ? (vbmp->line[1] - vbmp->line[0]) / bpp
                 : vbmp->w);

    glEnable(vid->target);
    glBindTexture(vid->target, vid->tex);
    glTexSubImage2D(vid->target, 0,
        x1, y1, x2 - x1 + 1, y2 - y1 + 1, format,
        type, vbmp->line[y1] + x1 * bpp);
    glBindTexture(vid->target, 0);
    glDisable(vid->target);

    if (temp)
        destroy_bitmap(temp);

    glPixelStorei(GL_UNPACK_ROW_LENGTH, saved_row_length);
    glPixelStorei(GL_UNPACK_ALIGNMENT, saved_alignment);
}



static void allegro_gl_video_putpixel(struct BITMAP *bmp, int x, int y,
                                      int color) {
    AGL_VIDEO_BITMAP *vid;

    if (is_sub_bitmap(bmp)) {
        x += bmp->x_ofs;
        y += bmp->y_ofs;
    }
    if (x < bmp->cl || x >= bmp->cr || y < bmp->ct || y >= bmp->cb) {
        return;
    }

    vid = bmp->extra;

    while (vid) {
        if (vid->x_ofs <= x && vid->y_ofs <= y
         && vid->x_ofs + vid->memory_copy->w > x
         && vid->y_ofs + vid->memory_copy->h > y) {

            set_drawing_pattern();
            putpixel(vid->memory_copy, x - vid->x_ofs, y - vid->y_ofs, color);
            unset_drawing_pattern();
            update_texture_memory(vid, x - vid->x_ofs, y - vid->y_ofs, x - vid->x_ofs, y - vid->y_ofs);
            break;
        }
        vid = vid->next;
    }
    
    return;
}



static void allegro_gl_video_vline(BITMAP *bmp, int x, int y1, int y2,
                                   int color) {

    AGL_VIDEO_BITMAP *vid;
    
    AGL_LOG(2, "glvtable.c:allegro_gl_video_vline\n");
    vid = bmp->extra;
    
    if (is_sub_bitmap(bmp)) {
        x  += bmp->x_ofs;
        y1 += bmp->y_ofs;
        y2 += bmp->y_ofs;
    }
    if (x < bmp->cl || x >= bmp->cr) {
        return;
    }
    
    if (y1 > y2) {
        int temp = y1;
        y1 = y2;
        y2 = temp;
    }

    if (y1 < bmp->ct) {
        y1 = bmp->ct;
    }
    if (y2 >= bmp->cb) {
        y2 = bmp->cb - 1;
    }

    while (vid) {
        BITMAP *vbmp = vid->memory_copy;
        
        int _y1, _y2, _x;
        if (vid->x_ofs > x || vid->y_ofs > y2
         || vid->x_ofs + vbmp->w <= x
         || vid->y_ofs + vbmp->h <= y1) {
            
            vid = vid->next;
            continue;
        }
        
        _y1 = MAX(y1, vid->y_ofs) - vid->y_ofs;
        _y2 = MIN(y2, vid->y_ofs + vbmp->h - 1) - vid->y_ofs;
        _x = x - vid->x_ofs;

        set_drawing_pattern();
        vline(vbmp, _x, _y1, _y2, color);
        unset_drawing_pattern();
        update_texture_memory(vid, _x, _y1, _x, _y2);

        vid = vid->next;
    }
    
    return;
}



static void allegro_gl_video_hline(BITMAP *bmp, int x1, int y, int x2,
                                   int color) {

    AGL_VIDEO_BITMAP *vid;
    
    AGL_LOG(2, "glvtable.c:allegro_gl_video_hline\n");
    vid = bmp->extra;

    if (is_sub_bitmap(bmp)) {
        x1 += bmp->x_ofs;
        x2 += bmp->x_ofs;
        y  += bmp->y_ofs;
    }

    if (y < bmp->ct || y >= bmp->cb) {
        return;
    }
    
    if (x1 > x2) {
        int temp = x1;
        x1 = x2;
        x2 = temp;
    }

    if (x1 < bmp->cl) {
        x1 = bmp->cl;
    }
    if (x2 >= bmp->cr) {
        x2 = bmp->cr - 1;
    }

    while (vid) {
        BITMAP *vbmp = vid->memory_copy;
        
        int _x1, _x2, _y;
        if (vid->y_ofs > y || vid->x_ofs > x2
         || vid->x_ofs + vbmp->w <= x1
         || vid->y_ofs + vbmp->h <= y) {
            
            vid = vid->next;
            continue;
        }
        
        _x1 = MAX(x1, vid->x_ofs) - vid->x_ofs;
        _x2 = MIN(x2, vid->x_ofs + vbmp->w - 1) - vid->x_ofs;
        _y = y - vid->y_ofs;

        set_drawing_pattern();
        hline(vbmp, _x1, _y, _x2, color);   
        unset_drawing_pattern();
        update_texture_memory(vid, _x1, _y, _x2, _y);

        vid = vid->next;
    }
    
    return;
}



static void allegro_gl_video_line(struct BITMAP *bmp, int x1, int y1, int x2,
                                  int y2, int color) {
    
    /* Note: very very slow */                      
    do_line(bmp, x1, y1, x2, y2, color, allegro_gl_video_putpixel);
    
    return;
}
    


static void allegro_gl_video_rectfill(struct BITMAP *bmp, int x1, int y1,
                                      int x2, int y2, int color) {

    AGL_VIDEO_BITMAP *vid;

    AGL_LOG(2, "glvtable.c:allegro_gl_video_rectfill\n");
    vid = bmp->extra;

    if (is_sub_bitmap(bmp)) {
        x1 += bmp->x_ofs;
        x2 += bmp->x_ofs;
        y1 += bmp->y_ofs;
        y2 += bmp->y_ofs;
    }
    
    if (y1 > y2) {
        int temp = y1;
        y1 = y2;
        y2 = temp;
    }

    if (x1 > x2) {
        int temp = x1;
        x1 = x2;
        x2 = temp;
    }

    if (x1 < bmp->cl) {
        x1 = bmp->cl;
    }
    if (x2 > bmp->cr) {
        x2 = bmp->cr;
    }
    if (y1 < bmp->ct) {
        y1 = bmp->ct;
    }
    if (y1 > bmp->cb) {
        y1 = bmp->cb;
    }

    while (vid) {
        BITMAP *vbmp = vid->memory_copy;
        
        int _y1, _y2, _x1, _x2;
        if (vid->x_ofs > x2 || vid->y_ofs > y2
         || vid->x_ofs + vbmp->w <= x1
         || vid->y_ofs + vbmp->h <= y1) {
            
            vid = vid->next;
            continue;
        }
        
        _y1 = MAX(y1, vid->y_ofs) - vid->y_ofs;
        _y2 = MIN(y2, vid->y_ofs + vbmp->h - 1) - vid->y_ofs;
        _x1 = MAX(x1, vid->x_ofs) - vid->x_ofs;
        _x2 = MIN(x2, vid->x_ofs + vbmp->w - 1) - vid->x_ofs;

        set_drawing_pattern();
        rectfill(vbmp, _x1, _y1, _x2, _y2, color);
        unset_drawing_pattern();

        update_texture_memory(vid, _x1, _y1, _x2, _y2);

        vid = vid->next;
    }

    return;
}


static void allegro_gl_video_triangle(struct BITMAP *bmp, int x1, int y1,
                                      int x2, int y2, int x3, int y3, int color)
{   
    AGL_VIDEO_BITMAP *vid;
    int min_y, max_y, min_x, max_x;

    AGL_LOG(2, "glvtable.c:allegro_gl_video_triangle\n");
    vid = bmp->extra;

    if (is_sub_bitmap(bmp)) {
        x1 += bmp->x_ofs;
        x2 += bmp->x_ofs;
        x3 += bmp->x_ofs;
        y1 += bmp->y_ofs;
        y2 += bmp->y_ofs;
        y3 += bmp->y_ofs;
    }

    min_y = MIN(y1, MIN(y2, y3));
    min_x = MIN(x1, MIN(x2, x3));
    max_y = MAX(y1, MAX(y2, y3));
    max_x = MAX(x1, MAX(x2, x3));

    while (vid) {
        BITMAP *vbmp = vid->memory_copy;
        
        int _y1, _y2, _x1, _x2, _x3, _y3;
        if (vid->x_ofs > max_x || vid->y_ofs > max_y
         || vid->x_ofs + vbmp->w <= min_x
         || vid->y_ofs + vbmp->h <= min_y) {
            
            vid = vid->next;
            continue;
        }
        
        _y1 = y1 - vid->y_ofs;
        _y2 = y2 - vid->y_ofs;
        _y3 = y3 - vid->y_ofs;
        _x1 = x1 - vid->x_ofs;
        _x2 = x2 - vid->x_ofs;
        _x3 = x3 - vid->x_ofs;

        set_clip_rect(vbmp, bmp->cl - vid->x_ofs, bmp->ct - vid->y_ofs,
                            bmp->cr - vid->x_ofs - 1, bmp->cb - vid->y_ofs - 1);

        set_drawing_pattern();

        triangle(vbmp, _x1, _y1, _x2, _y2, _x3, _y3, color);

        unset_drawing_pattern();

        set_clip_rect(vbmp, 0, 0, vbmp->w - 1, vbmp->h - 1);

        /* Not quite the minimal rectangle occupied by the triangle, but
        * pretty close */
        _y1 = MAX(0, min_y - vid->y_ofs);
        _y2 = MIN(vbmp->h - 1, max_y - vid->y_ofs);
        _x1 = MAX(0, min_x - vid->x_ofs);
        _x2 = MIN(vbmp->w - 1, max_x - vid->x_ofs);

        update_texture_memory(vid, _x1, _y1, _x2, _y2);

        vid = vid->next;
    }
}



static void allegro_gl_video_blit_from_memory_ex(BITMAP *source, BITMAP *dest,
                    int source_x, int source_y, int dest_x, int dest_y,
                    int width, int height, int draw_type) {

    AGL_VIDEO_BITMAP *vid;
    BITMAP *dest_parent = dest;
    
    if (is_sub_bitmap (dest)) {
       dest_x += dest->x_ofs;
       dest_y += dest->y_ofs;
       while (dest_parent->id & BMP_ID_SUB)
          dest_parent = (BITMAP *)dest_parent->extra;
    }

    if (dest_x < dest->cl) {
        dest_x = dest->cl;
    }
    if (dest_y < dest->ct) {
        dest_y = dest->ct;
    }
    if (dest_x + width >= dest->cr) {
        width = dest->cr - dest_x;
    }
    if (dest_y + height >= dest->cb) {
        height = dest->cb - dest_y;
    }
    if (width < 1 || height < 1) {
        return;
    }
    
    vid = dest_parent->extra;

    while (vid) {
        BITMAP *vbmp = vid->memory_copy;

        int _x, _y, _w, _h, _sx, _sy;
        if (vid->x_ofs >= dest_x + width || vid->y_ofs >= dest_y + height
         || vid->x_ofs + vbmp->w <= dest_x
         || vid->y_ofs + vbmp->h <= dest_y) {
            
            vid = vid->next;
            continue;
        }

        _x = MAX (vid->x_ofs, dest_x) - vid->x_ofs;
        _w = MIN (vid->x_ofs + vbmp->w, dest_x + width)
           - vid->x_ofs - _x;
        _y = MAX (vid->y_ofs, dest_y) - vid->y_ofs;
        _h = MIN (vid->y_ofs + vbmp->h, dest_y + height)
           - vid->y_ofs - _y;

        _sx = source_x + vid->x_ofs + _x - dest_x;
        _sy = source_y + vid->y_ofs + _y - dest_y;

        if (draw_type == BLIT) {
            blit(source, vbmp, _sx, _sy, _x, _y, _w, _h);
        }
        else if (draw_type == MASKED_BLIT) {
            masked_blit(source, vbmp, _sx, _sy, _x, _y, _w, _h);
        }
        else if (draw_type == TRANS) {
            BITMAP *clip = create_sub_bitmap(source, _sx, _sy, _w, _h);
            if (!clip)
                return;
            draw_trans_sprite(vbmp, clip, _x, _y);
            destroy_bitmap(clip);
        }

        update_texture_memory(vid, _x, _y, _x + _w - 1, _y + _h - 1);

        vid = vid->next;
    }

    return; 
}


void allegro_gl_video_blit_from_memory(BITMAP *source, BITMAP *dest,
                    int source_x, int source_y, int dest_x, int dest_y,
                    int width, int height) {

    allegro_gl_video_blit_from_memory_ex(source, dest, source_x, source_y,
                                         dest_x, dest_y, width, height, BLIT);
    return;
}



void allegro_gl_video_blit_to_memory(struct BITMAP *source, struct BITMAP *dest,
                         int source_x, int source_y, int dest_x, int dest_y,
                         int width, int height) {

    AGL_VIDEO_BITMAP *vid;
    BITMAP *source_parent = source;
    
    AGL_LOG(2, "glvtable.c:allegro_gl_video_blit_to_memory\n");
    
    if (is_sub_bitmap(source)) {
       source_x += source->x_ofs;
       source_y += source->y_ofs;
       while (source_parent->id & BMP_ID_SUB)
          source_parent = (BITMAP *)source_parent->extra;
    }

    vid = source_parent->extra;
    
    while (vid) {
        BITMAP *vbmp = vid->memory_copy;
        int x, y, dx, dy, w, h;

        x = MAX(source_x, vid->x_ofs) - vid->x_ofs;
        y = MAX(source_y, vid->y_ofs) - vid->y_ofs;
        w = MIN(vid->x_ofs + vbmp->w, source_x + width) - vid->x_ofs;
        h = MIN(vid->y_ofs + vbmp->h, source_y + height) - vid->y_ofs;
        dx = MAX(0, vid->x_ofs - source_x) + dest_x;
        dy = MAX(0, vid->y_ofs - source_y) + dest_y;

        blit(vbmp, dest, x, y, dx, dy, w, h);
    
        vid = vid->next;
    }

    return; 
}



/* Just like allegro_gl_video_blit_from_memory(), except that draws only to the
 * memory copy.
 */
static void __video_update_memory_copy(BITMAP *source, BITMAP *dest,
                            int source_x, int source_y, int dest_x, int dest_y,
                            int width, int height, int draw_type) {
    AGL_VIDEO_BITMAP *vid;
    BITMAP *dest_parent = dest;
    
    if (is_sub_bitmap (dest)) {
       dest_x += dest->x_ofs;
       dest_y += dest->y_ofs;
       while (dest_parent->id & BMP_ID_SUB)
          dest_parent = (BITMAP *)dest_parent->extra;
    }

    if (dest_x < dest->cl) {
        dest_x = dest->cl;
    }
    if (dest_y < dest->ct) {
        dest_y = dest->ct;
    }
    if (dest_x + width >= dest->cr) {
        width = dest->cr - dest_x;
    }
    if (dest_y + height >= dest->cb) {
        height = dest->cb - dest_y;
    }
    if (width < 1 || height < 1) {
        return;
    }
    
    vid = dest_parent->extra;

    while (vid) {
        int sx, sy;
        BITMAP *vbmp = vid->memory_copy;

        int dx, dy, w, h;
        if (vid->x_ofs >= dest_x + width || vid->y_ofs >= dest_y + height
         || vid->x_ofs + vbmp->w <= dest_x
         || vid->y_ofs + vbmp->h <= dest_y) {
            
            vid = vid->next;
            continue;
        }

        dx = MAX (vid->x_ofs, dest_x) - vid->x_ofs;
        w = MIN (vid->x_ofs + vbmp->w, dest_x + width)
           - vid->x_ofs - dx;
        dy = MAX (vid->y_ofs, dest_y) - vid->y_ofs;
        h = MIN (vid->y_ofs + vbmp->h, dest_y + height)
           - vid->y_ofs - dy;

        sx = source_x + vid->x_ofs + dx - dest_x;
        sy = source_y + vid->y_ofs + dy - dest_y;

        if (draw_type == MASKED_BLIT) {
            masked_blit(source, vbmp, sx, sy, dx, dy, w, h);
        }
        else if (draw_type == BLIT) {
            blit(source, vbmp, sx, sy, dx, dy, w, h);
        }
        else if (draw_type == TRANS) {
            BITMAP *clip = create_sub_bitmap(source, sx, sy, w, h);
            if (!clip)
                return;
            draw_trans_sprite(vbmp, clip, dx, dy);
            destroy_bitmap(clip);
        }

        vid = vid->next;
    }
    
    return;
}


#define FOR_EACH_TEXTURE_FRAGMENT(  \
    screen_blit_from_vid,           /* used when dest is FBO to blit to texture 
                                       memory from video bitmap */                \
    screen_blit_from_mem,           /* used when dest is FBO to blit to texture
                                       memory from memory bitmap */               \
    mem_copy_blit_from_vid,         /* used to update the memory copy of the
                                       dest from the source video bitmap */       \
    mem_copy_blit_from_mem,         /* used to update the memory copy of the
                                       dest from the source memory bitmap */      \
    vid_and_mem_copy_blit_from_vid, /* used when dest is not FBO, draws to both
                                       memory copy and texute memory of the dest,
                                       from video bitmap source*/                 \
    vid_and_mem_copy_blit_from_mem) /* used when dest is not FBO, draws to both
                                       memory copy and texute memory of the dest,
                                       from memory bitmap source */               \
{                                                          \
    int used_fbo = FALSE;                                  \
    AGL_VIDEO_BITMAP *vid;                                 \
                                                           \
    vid = dest->extra;                                     \
    if (vid->fbo) {                                        \
        int sx, sy;                                        \
        int dx, dy;                                        \
        int w, h;                                          \
                                                           \
        static GLint v[4];                                 \
        static double allegro_gl_projection_matrix[16];    \
        static double allegro_gl_modelview_matrix[16];     \
                                                           \
        glGetIntegerv(GL_VIEWPORT, &v[0]);                 \
        glMatrixMode(GL_MODELVIEW);                        \
        glGetDoublev(GL_MODELVIEW_MATRIX, allegro_gl_modelview_matrix);   \
        glMatrixMode(GL_PROJECTION);                                      \
        glGetDoublev(GL_PROJECTION_MATRIX, allegro_gl_projection_matrix); \
                                                                          \
        while (vid) {                                                     \
            if (dest_x >= vid->x_ofs + vid->memory_copy->w ||             \
                dest_y >= vid->y_ofs + vid->memory_copy->h ||             \
                vid->x_ofs >= dest_x + width ||          \
                vid->y_ofs >= dest_y + height) {         \
                vid = vid->next;                         \
                continue;                                \
            }                                            \
                                                         \
            dx = MAX(vid->x_ofs, dest_x) - vid->x_ofs;                  \
            w = MIN(vid->x_ofs + vid->memory_copy->w, dest_x + width)   \
              - vid->x_ofs - dx;                                        \
            dy = MAX(vid->y_ofs, dest_y) - vid->y_ofs;                  \
            h = MIN(vid->y_ofs + vid->memory_copy->h, dest_y + height)  \
              - vid->y_ofs - dy;                                        \
                                                                        \
            sx = source_x + vid->x_ofs + dx - dest_x;                   \
            sy = source_y + vid->y_ofs + dy - dest_y;                   \
                                                                        \
            glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, vid->fbo);         \
                                                                        \
            glViewport(0, 0, vid->memory_copy->w, vid->memory_copy->h); \
            glMatrixMode(GL_PROJECTION);                                \
            glLoadIdentity();                                           \
            gluOrtho2D(0, vid->memory_copy->w, 0, vid->memory_copy->h); \
            glMatrixMode(GL_MODELVIEW);                                 \
                                             \
            if (is_memory_bitmap(source)) {  \
                screen_blit_from_mem;        \
            }                                \
            else {                           \
                screen_blit_from_vid;        \
            }                                \
                                \
            vid = vid->next;    \
        }                       \
                                \
        glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0); \
                                                     \
        glViewport(v[0], v[1], v[2], v[3]);          \
        glMatrixMode(GL_PROJECTION);                 \
        glLoadMatrixd(allegro_gl_projection_matrix); \
        glMatrixMode(GL_MODELVIEW);                  \
        glLoadMatrixd(allegro_gl_modelview_matrix);  \
                                          \
        used_fbo = TRUE;                  \
    }                                     \
                                          \
    if (is_video_bitmap(source)) {        \
        int sx, sy;      \
        int dx, dy;      \
        int w, h;        \
                         \
        vid = source->extra;   \
                               \
        while (vid) {          \
            if (source_x >= vid->x_ofs + vid->memory_copy->w ||  \
                source_y >= vid->y_ofs + vid->memory_copy->h ||  \
                vid->x_ofs >= source_x + width ||                \
                vid->y_ofs >= source_y + height) {               \
                vid = vid->next;                                 \
                continue;                                        \
            }                                                    \
                                                                 \
            sx = MAX(vid->x_ofs, source_x) - vid->x_ofs;         \
            w = MIN(vid->x_ofs + vid->memory_copy->w, source_x + width)  \
              - vid->x_ofs - sx;                                         \
            sy = MAX(vid->y_ofs, source_y) - vid->y_ofs;                 \
            h = MIN(vid->y_ofs + vid->memory_copy->h, source_y + height) \
              - vid->y_ofs - sy;                                         \
                                                                         \
            dx = dest_x + vid->x_ofs + sx - source_x;  \
            dy = dest_y + vid->y_ofs + sy - source_y;  \
                                                       \
            if (used_fbo) {                            \
                mem_copy_blit_from_vid;                \
            }                                          \
            else {                                     \
                vid_and_mem_copy_blit_from_vid;        \
            }                                  \
                                               \
            vid = vid->next;                   \
        }                                      \
    }                                          \
    else if (is_memory_bitmap(source)) {       \
        if (used_fbo) {                        \
            mem_copy_blit_from_mem;            \
        }                                      \
        else {                                 \
            vid_and_mem_copy_blit_from_mem;    \
        }                                      \
    }                                          \
}


/* allegro_gl_video_blit_to_self:
 * blit() overload for video -> video blits
 */
void allegro_gl_video_blit_to_self(struct BITMAP *source, struct BITMAP *dest,
    int source_x, int source_y, int dest_x, int dest_y, int width, int height) {

    FOR_EACH_TEXTURE_FRAGMENT (
        allegro_gl_screen_blit_to_self(source, screen, sx, sy, dx, dy, w, h),
        allegro_gl_screen_blit_to_self(source, screen, sx, sy, dx, dy, w, h),
        __video_update_memory_copy(vid->memory_copy, dest, sx, sy, dx, dy, w, h, BLIT),
        __video_update_memory_copy(source, dest, source_x, source_y, dest_x, dest_y, width, height, BLIT),
        allegro_gl_video_blit_from_memory(vid->memory_copy, dest, sx, sy, dx, dy, w, h),
        allegro_gl_video_blit_from_memory(source, dest, source_x, source_y, dest_x, dest_y, width, height)
    )
}


static void do_masked_blit_video(struct BITMAP *source, struct BITMAP *dest,
            int source_x, int source_y, int dest_x, int dest_y,
            int width, int height, int flip_dir, int blit_type) {

    FOR_EACH_TEXTURE_FRAGMENT (
        do_masked_blit_screen(source, screen, sx, sy, dx, dy, w, h, flip_dir, blit_type),
        do_masked_blit_screen(source, screen, sx, sy, dx, dy, w, h, flip_dir, blit_type),
        __video_update_memory_copy(vid->memory_copy, dest, sx, sy, dx, dy, w, h, MASKED_BLIT),
        __video_update_memory_copy(source, dest, source_x, source_y, dest_x, dest_y, width, height, MASKED_BLIT),
        allegro_gl_video_blit_from_memory_ex(vid->memory_copy, dest, sx, sy, dx, dy, w, h, MASKED_BLIT),
        allegro_gl_video_blit_from_memory_ex(source, dest, source_x, source_y, dest_x, dest_y, width, height, MASKED_BLIT)
    )
}


/* allegro_gl_video_masked_blit:
 * masked_blit() overload for video -> video masked blits
 */
static void allegro_gl_video_masked_blit(struct BITMAP *source,
                struct BITMAP *dest, int source_x, int source_y,
                int dest_x, int dest_y, int width, int height) {
    do_masked_blit_video(source, dest, source_x, source_y, dest_x, dest_y,
                         width, height, FALSE, AGL_REGULAR_BMP | AGL_NO_ROTATION);

    return;
}


/* allegro_gl_video_draw_sprite:
 * draw_sprite() overload for video -> video sprite drawing
 */
static void allegro_gl_video_draw_sprite(struct BITMAP *bmp,
                        struct BITMAP *sprite, int x, int y) {

    do_masked_blit_video(sprite, bmp, 0, 0, x, y, sprite->w, sprite->h,
                         FALSE, AGL_NO_ROTATION);

    return;
}


/* allegro_gl_video_draw_sprite_v_flip:
 * draw_sprite_v_flip() overload for video -> video blits
 * FIXME: Broken if the bitmap was split into multiple textures.
 * FIXME: Doesn't apply rotation and scale to the memory copy
 */
static void allegro_gl_video_draw_sprite_v_flip(struct BITMAP *bmp,
                        struct BITMAP *sprite, int x, int y) {

    do_masked_blit_video(sprite, bmp, 0, 0, x, y, sprite->w, sprite->h,
                         AGL_V_FLIP, AGL_NO_ROTATION);

    return;
}


/* allegro_gl_video_draw_sprite_h_flip:
 * draw_sprite_v_flip() overload for video -> video blits
 * FIXME: Broken if the bitmap was split into multiple textures.
 * FIXME: Doesn't apply rotation and scale to the memory copy
 */
static void allegro_gl_video_draw_sprite_h_flip(struct BITMAP *bmp,
                        struct BITMAP *sprite, int x, int y) {

    do_masked_blit_video(sprite, bmp, 0, 0, x, y, sprite->w, sprite->h,
                         AGL_H_FLIP, AGL_NO_ROTATION);

    return;
}


/* allegro_gl_video_draw_sprite_vh_flip:
 * draw_sprite_vh_flip() overload for video -> video blits
 * FIXME: Broken if the bitmap was split into multiple textures.
 * FIXME: Doesn't apply rotation and scale to the memory copy
 */
static void allegro_gl_video_draw_sprite_vh_flip(struct BITMAP *bmp,
                        struct BITMAP *sprite, int x, int y) {

    do_masked_blit_video(sprite, bmp, 0, 0, x, y, sprite->w, sprite->h,
                         AGL_V_FLIP | AGL_H_FLIP, AGL_NO_ROTATION);

    return;
}


/* allegro_gl_video_pivot_scaled_sprite_flip:
 * FIXME: Broken if the bitmap was split into multiple textures.
 * FIXME: Doesn't apply rotation and scale to the memory copy
 * FIXME: Doesn't work for when FBO is not available.
 */
static void allegro_gl_video_pivot_scaled_sprite_flip(struct BITMAP *bmp,
            struct BITMAP *sprite, fixed x, fixed y, fixed cx, fixed cy,
            fixed angle, fixed scale, int v_flip) {
    double dscale = fixtof(scale);
    GLint matrix_mode;
    
#define BIN_2_DEG(x) (-(x) * 180.0 / 128)
    
    glGetIntegerv(GL_MATRIX_MODE, &matrix_mode);
    glMatrixMode(GL_MODELVIEW);
    glPushMatrix();
    glTranslated(fixtof(x), fixtof(y), 0.);
    glRotated(BIN_2_DEG(fixtof(angle)), 0., 0., -1.);
    glScaled(dscale, dscale, dscale);
    glTranslated(-fixtof(x+cx), -fixtof(y+cy), 0.);
    
    do_masked_blit_video(sprite, bmp, 0, 0, fixtoi(x), fixtoi(y),
                          sprite->w, sprite->h, v_flip ? AGL_V_FLIP : FALSE, FALSE);
    glPopMatrix();
    glMatrixMode(matrix_mode);

#undef BIN_2_DEG

    return;
}


/* allegro_gl_video_do_stretch_blit:
 * overload for all kind of video -> video and video -> screen stretchers
 * FIXME: Doesn't apply scale to the memory copy
 * FIXME: Doesn't work for video->video when FBO is not available.
 */
static void allegro_gl_video_do_stretch_blit(BITMAP *source, BITMAP *dest,
               int source_x, int source_y, int source_width, int source_height,
               int dest_x, int dest_y, int dest_width, int dest_height,
               int masked) {
    /* note: src is a video bitmap, dest is not a memory bitmap */

    double scalew = ((double)dest_width) / source_width;
    double scaleh = ((double)dest_height) / source_height;
    
    GLint matrix_mode;

    /* BITMAP_BLIT_CLIP macro from glvtable.c is no good for scaled images. */
    if (dest->clip) {
        if ((dest_x >= dest->cr) || (dest_y >= dest->cb)
         || (dest_x + dest_width < dest->cl) || (dest_y + dest_height < dest->ct)) {
            return;
        }
        if (dest_x < dest->cl) {
            source_x -= (dest_x - dest->cl) / scalew;
            dest_x = dest->cl;
        }
        if (dest_y < dest->ct) {
            source_y -= (dest_y - dest->ct) / scaleh;
            dest_y = dest->ct;
        }
        if (dest_x + dest_width > dest->cr) {
            source_width -= (dest_x + dest_width - dest->cr) / scalew;
            dest_width = dest->cr - dest_x;
        }
        if (dest_y + dest_height > dest->cb) {
            source_height -= (dest_y + dest_height - dest->cb) / scaleh;
            dest_height = dest->cb - dest_y;
        }
    }

    glGetIntegerv(GL_MATRIX_MODE, &matrix_mode);
    glMatrixMode(GL_MODELVIEW);
    glPushMatrix();
    glTranslated(dest_x, dest_y, 0.);
    glScaled(scalew, scaleh, 1.);
    glTranslated(-dest_x, -dest_y, 0.);

    if (masked) {
        if (is_screen_bitmap(dest)) {
            do_masked_blit_screen(source, dest, source_x, source_y,
                                  dest_x, dest_y, source_width, source_height,
                                  FALSE, AGL_REGULAR_BMP);
        }
        else {
            do_masked_blit_video(source, dest, source_x, source_y,
                                 dest_x, dest_y, source_width, source_height,
                                 FALSE, AGL_REGULAR_BMP);
        }
    }
    else {
        allegro_gl_screen_blit_to_self(source, dest, source_x, source_y,
                           dest_x, dest_y, source_width, source_height);
    }

    glPopMatrix();
    glMatrixMode(matrix_mode);

    return;
}



/* allegro_gl_video_draw_trans_rgba_sprite:
 * draw_trans_sprite() overload for video -> video drawing
 */
static void allegro_gl_video_draw_trans_rgba_sprite(BITMAP *bmp,
                                BITMAP *sprite, int x, int y) {
    /* Adapt variables for FOR_EACH_TEXTURE_FRAGMENT macro. */
    BITMAP *source = sprite;
    BITMAP *dest = bmp;
    int dest_x = x;
    int dest_y = y;
    int source_x = 0;
    int source_y = 0;
    int width = sprite->w;
    int height = sprite->h;
    GLint format = __allegro_gl_get_bitmap_color_format(sprite, AGL_TEXTURE_HAS_ALPHA);
    GLint type = __allegro_gl_get_bitmap_type(sprite, 0);

    if (__allegro_gl_blit_operation == AGL_OP_LOGIC_OP)
        glEnable(GL_COLOR_LOGIC_OP);
    else
        glEnable(GL_BLEND);

    FOR_EACH_TEXTURE_FRAGMENT (
        allegro_gl_screen_blit_to_self(source, screen, sx, sy, dx, dy, w, h),
        allegro_gl_upload_and_display_texture(sprite, sx, sy, dx, dy, w, h, 0, format, type),
        __video_update_memory_copy(vid->memory_copy, dest, sx, sy, dx, dy, w, h, TRANS),
        __video_update_memory_copy(source, dest, 0, 0, x, y, sprite->w, sprite->h, TRANS),
        allegro_gl_video_blit_from_memory_ex(vid->memory_copy, dest, sx, sy, dx, dy, w, h, TRANS),
        allegro_gl_video_blit_from_memory_ex(source, dest, 0, 0, x, y, sprite->w, sprite->h, TRANS)
    )

    if (__allegro_gl_blit_operation == AGL_OP_LOGIC_OP)
        glDisable(GL_COLOR_LOGIC_OP);
    else
        glDisable(GL_BLEND);

    return;
}



static void allegro_gl_video_clear_to_color(BITMAP *bmp, int color) {
    AGL_VIDEO_BITMAP *vid = bmp->extra;

    if (vid->fbo) {
        static GLint v[4];
        static double allegro_gl_projection_matrix[16];
        static double allegro_gl_modelview_matrix[16];

        glGetIntegerv(GL_VIEWPORT, &v[0]);
        glMatrixMode(GL_MODELVIEW);
        glGetDoublev(GL_MODELVIEW_MATRIX, allegro_gl_modelview_matrix);
        glMatrixMode(GL_PROJECTION);
        glGetDoublev(GL_PROJECTION_MATRIX, allegro_gl_projection_matrix);

        while (vid) {
            glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, vid->fbo);

            glViewport(0, 0, vid->memory_copy->w, vid->memory_copy->h);
            glMatrixMode(GL_PROJECTION);
            glLoadIdentity();
            gluOrtho2D(0, vid->memory_copy->w, 0, vid->memory_copy->h);
            glMatrixMode(GL_MODELVIEW);

            allegro_gl_screen_clear_to_color(bmp, color);
            clear_to_color(vid->memory_copy, color);
            vid = vid->next;
        }

        glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);
    
        glViewport(v[0], v[1], v[2], v[3]);
        glMatrixMode(GL_PROJECTION);
        glLoadMatrixd(allegro_gl_projection_matrix);
        glMatrixMode(GL_MODELVIEW);
        glLoadMatrixd(allegro_gl_modelview_matrix);
    }
    else {
        allegro_gl_video_rectfill(bmp, 0, 0, bmp->w, bmp->h, color);
    }
}



/* FIXME: Doesn't work when FBO is not available.
 * FIXME: Doesn't care for segmented video bitmaps.
 */
static void allegro_gl_video_draw_color_glyph(struct BITMAP *bmp,
    struct BITMAP *sprite, int x, int y, int color, int bg)
{
    AGL_VIDEO_BITMAP *vid = bmp->extra;

    static GLint v[4];
    static double allegro_gl_projection_matrix[16];
    static double allegro_gl_modelview_matrix[16];

    if (!vid->fbo)
        return;

    glGetIntegerv(GL_VIEWPORT, &v[0]);
    glMatrixMode(GL_MODELVIEW);
    glGetDoublev(GL_MODELVIEW_MATRIX, allegro_gl_modelview_matrix);
    glMatrixMode(GL_PROJECTION);
    glGetDoublev(GL_PROJECTION_MATRIX, allegro_gl_projection_matrix);

    glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, vid->fbo);

    glViewport(0, 0, vid->memory_copy->w, vid->memory_copy->h);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluOrtho2D(0, vid->memory_copy->w, 0, vid->memory_copy->h);
    glMatrixMode(GL_MODELVIEW);

    allegro_gl_screen_draw_color_glyph_ex(bmp, sprite, x, y, color, bg, 0);

    glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);

    glViewport(v[0], v[1], v[2], v[3]);
    glMatrixMode(GL_PROJECTION);
    glLoadMatrixd(allegro_gl_projection_matrix);
    glMatrixMode(GL_MODELVIEW);
    glLoadMatrixd(allegro_gl_modelview_matrix);

    vid->memory_copy->vtable->draw_character(vid->memory_copy, sprite, x, y, color, bg);
}



static void allegro_gl_video_draw_256_sprite(BITMAP *bmp, BITMAP *sprite,
                                      int x, int y) {
    allegro_gl_video_draw_color_glyph(bmp, sprite, x, y, -1, _textmode);
}



static void allegro_gl_video_draw_character(BITMAP *bmp, BITMAP *sprite,
                                            int x, int y, int color, int bg) {
    allegro_gl_video_draw_color_glyph(bmp, sprite, x, y, color, bg);
}



/* FIXME: Doesn't work when FBO is not available.
 * FIXME: Doesn't care for segmented video bitmaps.
 */
static void allegro_gl_video_draw_glyph(struct BITMAP *bmp,
                               AL_CONST struct FONT_GLYPH *glyph, int x, int y,
                               int color, int bg) {
    AGL_VIDEO_BITMAP *vid = bmp->extra;

    static GLint v[4];
    static double allegro_gl_projection_matrix[16];
    static double allegro_gl_modelview_matrix[16];

    if (!vid->fbo)
        return;

    glGetIntegerv(GL_VIEWPORT, &v[0]);
    glMatrixMode(GL_MODELVIEW);
    glGetDoublev(GL_MODELVIEW_MATRIX, allegro_gl_modelview_matrix);
    glMatrixMode(GL_PROJECTION);
    glGetDoublev(GL_PROJECTION_MATRIX, allegro_gl_projection_matrix);

    glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, vid->fbo);

    glViewport(0, 0, vid->memory_copy->w, vid->memory_copy->h);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluOrtho2D(0, vid->memory_copy->w, 0, vid->memory_copy->h);
    glMatrixMode(GL_MODELVIEW);

    allegro_gl_screen_draw_glyph_ex(bmp, glyph, x, y, color, bg, 1);

    glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);

    glViewport(v[0], v[1], v[2], v[3]);
    glMatrixMode(GL_PROJECTION);
    glLoadMatrixd(allegro_gl_projection_matrix);
    glMatrixMode(GL_MODELVIEW);
    glLoadMatrixd(allegro_gl_modelview_matrix);

    vid->memory_copy->vtable->draw_glyph(vid->memory_copy, glyph, x, y, color, bg);
}



static void allegro_gl_video_polygon3d_f(BITMAP *bmp, int type, BITMAP *texture,
                                  int vc, V3D_f *vtx[])
{
    AGL_VIDEO_BITMAP *vid = bmp->extra;

    /* Switch to software mode is using polygon type that isn't supported by
       allegro_gl_screen_polygon3d_f. */
    int use_fbo = (type == POLYTYPE_FLAT) ||
                  (type == POLYTYPE_GRGB) ||
                  (type == POLYTYPE_GCOL) ||
                  (type == POLYTYPE_ATEX) ||
                  (type == POLYTYPE_PTEX) ||
                  (type == POLYTYPE_ATEX_TRANS) ||
                  (type == POLYTYPE_PTEX_TRANS);

    if (vid->fbo && use_fbo) {
        static GLint v[4];
        static double allegro_gl_projection_matrix[16];
        static double allegro_gl_modelview_matrix[16];

        glGetIntegerv(GL_VIEWPORT, &v[0]);
        glMatrixMode(GL_MODELVIEW);
        glGetDoublev(GL_MODELVIEW_MATRIX, allegro_gl_modelview_matrix);
        glMatrixMode(GL_PROJECTION);
        glGetDoublev(GL_PROJECTION_MATRIX, allegro_gl_projection_matrix);

        while (vid) {
            BITMAP *mem_texture;

            glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, vid->fbo);

            glViewport(0, 0, vid->memory_copy->w, vid->memory_copy->h);
            glMatrixMode(GL_PROJECTION);
            glLoadIdentity();
            gluOrtho2D(0, vid->memory_copy->w, 0, vid->memory_copy->h);
            glMatrixMode(GL_MODELVIEW);

            allegro_gl_screen_polygon3d_f(bmp, type, texture, vc, vtx);

            if (is_video_bitmap(texture)) {
                AGL_VIDEO_BITMAP *vbmp = texture->extra;
                mem_texture = vbmp->memory_copy;
            }
            else {
                mem_texture = texture;
            }
            polygon3d_f(vid->memory_copy, type, mem_texture, vc, vtx);

            vid = vid->next;
        }

        glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);
    
        glViewport(v[0], v[1], v[2], v[3]);
        glMatrixMode(GL_PROJECTION);
        glLoadMatrixd(allegro_gl_projection_matrix);
        glMatrixMode(GL_MODELVIEW);
        glLoadMatrixd(allegro_gl_modelview_matrix);
    }
    else {
        int i;
        AGL_VIDEO_BITMAP *vid;
    
        vid = bmp->extra;
    
        if (is_sub_bitmap(bmp)) {
            for (i = 0; i < vc; ++i) {
                vtx[i]->x += bmp->x_ofs;
                vtx[i]->y += bmp->y_ofs;
            }
        }

        while (vid) {
            BITMAP *mem_texture;
            int _y1, _y2, _x1, _x2;
            BITMAP *vbmp = vid->memory_copy;

            _x1 = 9999;
            for (i = 0; i < vc; ++i)
                if (vtx[i]->x < _x1) _x1 = vtx[i]->x;

            _x2 = -9999;
            for (i = 0; i < vc; ++i)
                if (vtx[i]->x > _x2) _x2 = vtx[i]->x;

            _y1 = 9999;
            for (i = 0; i < vc; ++i)
                if (vtx[i]->y < _y1) _y1 = vtx[i]->y;

            _y2 = -9999;
            for (i = 0; i < vc; ++i)
                if (vtx[i]->y > _y2) _y2 = vtx[i]->y;

            if (vid->x_ofs > _x2 || vid->y_ofs > _y2
             || vid->x_ofs + vbmp->w <= _x1
             || vid->y_ofs + vbmp->h <= _y1) {
                
                vid = vid->next;
                continue;
            }
            
            _x1 = MAX(0, _x1 - vid->x_ofs);
            _x2 = (_x2 - (vid->x_ofs + vbmp->w) > 0) ? vbmp->w - 1: _x2 - vid->x_ofs;
            _y1 = MAX(0, _y1 - vid->y_ofs);
            _y2 = (_x2 - (vid->y_ofs + vbmp->h) > 0) ? vbmp->h - 1: _y2 - vid->y_ofs;

            if (is_video_bitmap(texture)) {
                AGL_VIDEO_BITMAP *tex = texture->extra;
                mem_texture = tex->memory_copy;
            }
            else {
                mem_texture = texture;
            }
            polygon3d_f(vid->memory_copy, type, mem_texture, vc, vtx);
    
            update_texture_memory(vid, _x1, _y1, _x2, _y2);
    
            vid = vid->next;
        }
    }

    return;
}



static void allegro_gl_video_polygon3d(BITMAP *bmp, int type, BITMAP *texture,
                                int vc, V3D *vtx[])
{
    int i;
    V3D_f **vtx_f = malloc(vc * sizeof(struct V3D_f*));
    if (!vtx_f)
        return;

    for (i = 0; i < vc; i++) {
        vtx_f[i] = malloc(sizeof(struct V3D_f));
        if (!vtx_f[i]) {
            int k;
            for (k = 0; k < i; k++)
                free(vtx_f[k]);
            free(vtx_f);
            return;
        }
        vtx_f[i]->c = vtx[i]->c;
        vtx_f[i]->u = fixtof(vtx[i]->u);
        vtx_f[i]->v = fixtof(vtx[i]->v);
        vtx_f[i]->x = fixtof(vtx[i]->x);
        vtx_f[i]->y = fixtof(vtx[i]->y);
        vtx_f[i]->z = fixtof(vtx[i]->z);
    }

    allegro_gl_video_polygon3d_f(bmp, type, texture, vc, vtx_f);

    for (i = 0; i < vc; i++)
        free(vtx_f[i]);
    free(vtx_f);
}



static void allegro_gl_video_triangle3d(BITMAP *bmp, int type, BITMAP *texture,
                                        V3D *v1, V3D *v2, V3D *v3)
{
    V3D *vtx[3] = {v1, v2, v3};
    allegro_gl_video_polygon3d(bmp, type, texture, 3, vtx);
}



static void allegro_gl_video_triangle3d_f(BITMAP *bmp, int type, BITMAP *texture,
                                          V3D_f *v1, V3D_f *v2, V3D_f *v3)
{
    V3D_f *vtx_f[3] = {v1, v2, v3};
    allegro_gl_video_polygon3d_f(bmp, type, texture, 3, vtx_f);
}



static void allegro_gl_video_quad3d(BITMAP *bmp, int type, BITMAP *texture,
                                    V3D *v1, V3D *v2, V3D *v3, V3D *v4)
{
    V3D *vtx[4] = {v1, v2, v3, v4};
    allegro_gl_video_polygon3d(bmp, type, texture, 4, vtx);
}



static void allegro_gl_video_quad3d_f(BITMAP *bmp, int type, BITMAP *texture,
                               V3D_f *v1, V3D_f *v2, V3D_f *v3, V3D_f *v4)
{
    V3D_f *vtx_f[4] = {v1, v2, v3, v4};
    allegro_gl_video_polygon3d_f(bmp, type, texture, 4, vtx_f);
}



static void dummy_unwrite_bank(void)
{
}



static GFX_VTABLE allegro_gl_video_vtable = {
    0,
    0,
    dummy_unwrite_bank,         //void *unwrite_bank;  /* C function on some machines, asm on i386 */
    NULL,                       //AL_METHOD(void, set_clip, (struct BITMAP *bmp));
    allegro_gl_video_acquire,
    allegro_gl_video_release,
    NULL,                       //AL_METHOD(struct BITMAP *, create_sub_bitmap, (struct BITMAP *parent, int x, int y, int width, int height));
    allegro_gl_created_sub_bitmap,
    allegro_gl_video_getpixel,
    allegro_gl_video_putpixel,
    allegro_gl_video_vline,
    allegro_gl_video_hline,
    allegro_gl_video_hline,
    allegro_gl_video_line,
    allegro_gl_video_line,
    allegro_gl_video_rectfill,
    allegro_gl_video_triangle,
    allegro_gl_video_draw_sprite,
    allegro_gl_video_draw_256_sprite,
    allegro_gl_video_draw_sprite_v_flip,
    allegro_gl_video_draw_sprite_h_flip,
    allegro_gl_video_draw_sprite_vh_flip,
    allegro_gl_video_draw_trans_rgba_sprite,
    allegro_gl_video_draw_trans_rgba_sprite,
    NULL,                       //AL_METHOD(void, draw_lit_sprite, (struct BITMAP *bmp, struct BITMAP *sprite, int x, int y, int color));
    NULL,                       //AL_METHOD(void, allegro_gl_video_draw_rle_sprite, (struct BITMAP *bmp, struct RLE_SPRITE *sprite, int x, int y));
    NULL,                       //AL_METHOD(void, draw_trans_rle_sprite, (struct BITMAP *bmp, struct RLE_SPRITE *sprite, int x, int y));
    NULL,                       //AL_METHOD(void, draw_trans_rgba_rle_sprite, (struct BITMAP *bmp, struct RLE_SPRITE *sprite, int x, int y));
    NULL,                       //AL_METHOD(void, draw_lit_rle_sprite, (struct BITMAP *bmp, struct RLE_SPRITE *sprite, int x, int y, int color));
    allegro_gl_video_draw_character,
    allegro_gl_video_draw_glyph,
    allegro_gl_video_blit_from_memory,
    allegro_gl_video_blit_to_memory,
    NULL,                       //AL_METHOD(void, blit_from_system, (struct BITMAP *source, struct BITMAP *dest, int source_x, int source_y, int dest_x, int dest_y, int width, int height));
    NULL,                       //AL_METHOD(void, blit_to_system, (struct BITMAP *source, struct BITMAP *dest, int source_x, int source_y, int dest_x, int dest_y, int width, int height));
    allegro_gl_screen_blit_to_self, /* Video bitmaps use same method as screen */
    allegro_gl_screen_blit_to_self, /* ..._forward */
    allegro_gl_screen_blit_to_self, /* ..._backward */
    allegro_gl_memory_blit_between_formats,
    allegro_gl_video_masked_blit,
    allegro_gl_video_clear_to_color,
    allegro_gl_video_pivot_scaled_sprite_flip,
    allegro_gl_video_do_stretch_blit,
    NULL,                       //AL_METHOD(void, draw_gouraud_sprite, (struct BITMAP *bmp, struct BITMAP *sprite, int x, int y, int c1, int c2, int c3, int c4));
    NULL,                       //AL_METHOD(void, draw_sprite_end, (void));
    NULL,                       //AL_METHOD(void, blit_end, (void));
    _soft_polygon,              //AL_METHOD(void, polygon, (struct BITMAP *bmp, int vertices, AL_CONST int *points, int color));
    _soft_rect,                 //AL_METHOD(void, rect, (struct BITMAP *bmp, int x1, int y1, int x2, int y2, int color));
    _soft_circle,               //AL_METHOD(void, circle, (struct BITMAP *bmp, int x, int y, int radius, int color));
    _soft_circlefill,           //AL_METHOD(void, circlefill, (struct BITMAP *bmp, int x, int y, int radius, int color));
    _soft_ellipse,              //AL_METHOD(void, ellipse, (struct BITMAP *bmp, int x, int y, int rx, int ry, int color));
    _soft_ellipsefill,          //AL_METHOD(void, ellipsefill, (struct BITMAP *bmp, int x, int y, int rx, int ry, int color));
    _soft_arc,                  //AL_METHOD(void, arc, (struct BITMAP *bmp, int x, int y, fixed ang1, fixed ang2, int r, int color));
    _soft_spline,               //AL_METHOD(void, spline, (struct BITMAP *bmp, AL_CONST int points[8], int color));
    _soft_floodfill,            //AL_METHOD(void, floodfill, (struct BITMAP *bmp, int x, int y, int color));
    allegro_gl_video_polygon3d,
    allegro_gl_video_polygon3d_f,
    allegro_gl_video_triangle3d,
    allegro_gl_video_triangle3d_f,
    allegro_gl_video_quad3d,
    allegro_gl_video_quad3d_f,
};

---