From:	ian_dunbar AT my-dejanews DOT com
Newsgroups:	comp.os.msdos.djgpp
Subject:	ALLEGRO: problem with bitmap palette from datafile
Date:	Mon, 08 Mar 1999 11:26:18 GMT
Organization:	Deja News - The Leader in Internet Discussion
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To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp
Reply-To:	djgpp AT delorie DOT com

Hi,

I have a problem displaying a 256 color bitmap. It is displayed as all the
wrong colors. I store the bitmap and palette in the datafile using the
following commands:

dat -a -h images/cardata.h images/cardata.dat images/car.bmp -t BMP
dat -u -h images/cardata.h images/cardata.dat CAR_BMP NAME=CAR_BMP_BMP
dat -a -h images/cardata.h images/cardata.dat images/car.bmp -t PALETTE
dat -u -h images/cardata.h images/cardata.dat CAR_BMP NAME=CAR_BMP_PAL

Then here's how I display the bitmap (more or less anyway, I've removed all
the irellevant code):

// Initialize the screen buffer
m_buffer = create_bitmap (320, 200);
clear_to_color (m_buffer, 0);

DATAFILE *dat = load_datafile ("images/cardata.dat");

if (dat == 0) return 0;

m_sprite = (BITMAP *)dat[CAR_BMP_BMP].dat;
set_palette ((RGB *)dat[CAR_BMP_PAL].dat);

// blit the car onto the buffer
masked_blit (m_sprite , m_buffer, 0, 0, 0, 0, 32, 20);

// Blit the buffer to the screen
blit (m_buffer, screen, 0, 0, 0, 0, 320, 200);

The set_palette definitely changes the palette from the default one, but not
to the one that will display the bitmap correctly. Any idea what I'm doing
wrong?

Thanks,
Ian.

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