debian man page for create_trans_table

create_trans_table(3alleg4)					  Allegro manual				       create_trans_table(3alleg4)

NAME
       create_trans_table - Fills a color mapping table for translucency effects. Allegro game programming library.

SYNOPSIS
       #include <allegro.h>

       void create_trans_table(COLOR_MAP *table, const PALETTE pal, int r, g, b, void (*callback)(int pos));

DESCRIPTION
       Fills the specified color mapping table with lookup data for doing translucency effects with the specified palette. When combining the col-
       ors c1 and c2 with this table, the result will be a color somewhere between the two. The r, g, and b parameters	specify  the  solidity	of
       each color component, ranging from 0 (totally transparent) to 255 (totally solid). For 50% solidity, pass 128.

       This  function  treats source color #0 as a special case, leaving the destination unchanged whenever a zero source pixel is encountered, so
       that masked sprites will draw correctly. This function will take advantage of the global rgb_map variable to speed up color conversions. If
       the  callback function is not NULL, it will be called 256 times during the calculation, allowing you to display a progress indicator. Exam-
       ple:

	  COLOR_MAP trans_table;
	  ...
	  /* Build a color lookup table for translucent drawing. */
	  create_trans_table(&trans_table, pal, 128, 128, 128, NULL);

SEE ALSO
       color_map(3alleg4), create_light_table(3alleg4),  create_color_table(3alleg4),  create_blender_table(3alleg4),  draw_trans_sprite(3alleg4),
       draw_lit_sprite(3alleg4), draw_gouraud_sprite(3alleg4), rgb_map(3alleg4), ex3d(3alleg4), extrans(3alleg4)

Allegro 							   version 4.4.2				       create_trans_table(3alleg4)