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getr_depth(3)                   Allegro manual                   getr_depth(3)

NAME
       getr_depth, getg_depth, getb_depth, geta_depth - Extract a color
       component from a color in a specified pixel format. Allegro game
       programming library.

SYNOPSIS
       #include <allegro.h>

       int getr_depth(int color_depth, int c);

       int getg_depth(int color_depth, int c);

       int getb_depth(int color_depth, int c);

       int geta_depth(int color_depth, int c);

DESCRIPTION
       Given a color in the format being used by the specified color depth,
       these functions extract one of the red, green, blue, or alpha
       components (ranging 0-255). The alpha part is only meaningful for
       32-bit pixels.  Example:

          int r, g, b, color_value, bpp;

          bpp = bitmap_color_depth(bitmap);
          color_value = getpixel(bitmap, 100, 100);
          r = getr_depth(bpp, color_value);
          g = getg_depth(bpp, color_value);
          b = getb_depth(bpp, color_value);

SEE ALSO
       getr(3), getr8(3), geta32(3), makecol(3), set_color_depth(3),
       exlights(3)

Allegro                          version 4.4.2                   getr_depth(3)