oracular (3) draw_trans_sprite.3alleg4.gz

NAME

       draw_trans_sprite - Draws a sprite blending it with the destination. Allegro game programming library.

SYNOPSIS

       #include <allegro.h>

       void draw_trans_sprite(BITMAP *bmp, BITMAP *sprite, int x, int y);

DESCRIPTION

       Uses  the  global  color_map  table  or  truecolor  blender functions to overlay the sprite on top of the
       existing image. This must only be used after you have set up  the  color  mapping  table  (for  256-color
       modes)  or  blender  functions  (for truecolor modes). Because it involves reading as well as writing the
       bitmap memory, translucent drawing is very slow if you draw directly to video RAM, so  wherever  possible
       you should use a memory bitmap instead. Example:

          /* Some one time initialisation code. */
          COLOR_MAP global_trans_table;
          create_trans_table(&global_trans_table, my_palette,
                             128, 128, 128, NULL);
          ...
          if (get_color_depth() == 8)
             color_map = &global_trans_table;
          else
             set_trans_blender(128, 128, 128, 128);

          draw_trans_sprite(buffer, ghost_sprite, x, y);

       The bitmap and sprite must normally be in the same color depth, but as a special case you can draw 32 bit
       RGBA format sprites onto any hicolor or truecolor bitmap, as long as you call set_alpha_blender()  first,
       and   you   can  draw  8-bit  alpha  images  onto  a  32-bit  RGBA  destination,  as  long  as  you  call
       set_write_alpha_blender() first. As draw_sprite() this function skips transparent pixels, except  if  the
       source  sprite  is  an 8-bit image; if this is the case, you should pay attention to properly set up your
       color map table for index 0.

SEE ALSO

       draw_sprite(3alleg4),   draw_lit_sprite(3alleg4),   draw_trans_rle_sprite(3alleg4),   color_map(3alleg4),
       set_trans_blender(3alleg4),         set_alpha_blender(3alleg4),         set_write_alpha_blender(3alleg4),
       bitmap_mask_color(3alleg4),  exalpha(3alleg4),  exblend(3alleg4),  exlights(3alleg4),  exrotscl(3alleg4),
       extrans(3alleg4), exxfade(3alleg4)