From:	"Jan Willem Penterman" <jw AT rel DOT nl>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: see-trough & sprites
Date:	Tue, 24 Nov 1998 14:17:06 +0100
Organization:	A2000 Kabeltelevisie & Telecommunicatie
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To:	djgpp AT delorie DOT com
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Reply-To:	djgpp AT delorie DOT com

Hey Lazer,

Hmm i dunno what you mean with better exactly, but i suppose
this code results in a flickering image on the screen. You'd better
use a backbuffer ( a "virtual" screen in your system memory) to
draw all sprites you have on, and then copy the whoole buffer- image at once
to the screen. An alternative is page-flipping, check the allegro examples
out, they're full of useful code.

Backbuffer example:


BITMAP *backBuffer = create_bitmap(SCREEN_W,SCREEN_H);

while(!key[KEY_ESC])
{
    clear(backBuffer);
    Q=Q+1;
    draw_sprite(backBuffer, my_image, Q, 200-my_image->h);

    // you draw all your other sprites and stuff here

    // when your finished drawing:
    blit(backBuffer, screen, 0 , 0, 0, 0, SCREEN_W, SCREEN_H);

}

As for transparant colours...well it might be possible in 8-bit resolution
but that probbably will look like shit, there's a 16-bit color example in
ex30
or ex31 ( i forgot...) in the allegro library... but I wouldn't recommend
that
coz of speed issue's :o)

Greetz, Jan Willem

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