Message-ID: <388492C5.4F7F7540@tiscalinet.it>
Date: Tue, 18 Jan 2000 17:20:21 +0100
From: Night Walker <night DOT walker AT tiscalinet DOT it>
X-Mailer: Mozilla 4.7 [en] (Win95; I)
X-Accept-Language: en
MIME-Version: 1.0
To: djgpp AT delorie DOT com
Subject: Allegro: Again on fast palette and blending....
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
Reply-To: djgpp AT delorie DOT com


Thanx to Damian Yerrick, but this won't solve my problem:

>>I must switch between palette tables quite fast: i must draw 8bpp
>>RLE_SPRITE on a truecolor screen, and each sprite has different
palette.
>Or you could cache them in memory as truecolor before you draw them.
>That would be faster.
I am working on a Starcraft-like game, and i must be able to draw each
unit in a different color, so each unit has a PALETTE array for each
player; so i can't cache them, because it would take too much ram (4
times more, isn't it?) and because i have to use the same sprites with
different palettes.

>>I messed around with Allegro SRC but I found set_pallete() quite
>>confusing.
>>Passing entire arrays (the PALLETE type) by value as function
parameters
>>is not slow/unefficent? or are they automatically passed by reference?

>>There is a way to simply redirect a pointer to a PALLETE table, thus
>>changing palette with only an assignement "="?
>>This will let me use blender maps/funx for transparency?
>>How can I learn to use them (about this topic  ALLEGRO.TXT is not very

>>clear for a newbie)
>PALETTE is defined as an array of RGB.
>Functions that take a PALETTE actually take RGB *, which can be
>accessed much the same way.

typedef RGB PALETTE[PAL_SIZE];    //is quite ambiguos, but now's ok...

>PALETTE pal;
>// fill the palette somehow, then
>set_palette(pal);

/*From GFX.C ==============================================
  set_pallete_range()
*/
 ...
   for (c=from; c<=to; c++) {
      _current_pallete[c] = p[c];
...
      if (_color_depth != 8)
  pallete_color[c] = makecol(_rgb_scale_6[p[c].r], _rgb_scale_6[p[c].g],
_rgb_scale_6[p[c].b]);
...
//that's not a code i can call every time i must draw a unit!!!
//EOF =====================================================

I was thinking about changing  _current_pallete from an array to a
pointer, fill all the pals i need in arrays and have _current_palette
point the array i need, thus changing pal with a single assignement...
Will it allow me to use blending?

About Blending:
Why are needed more than 1 blender func?
How can I initialize them for a simple transparency (50%) effect?

Thanx for your patience.... :-)))