/*
	tga.c

	targa image handling

	Copyright (C) 1996-1997  Id Software, Inc.

	This program is free software; you can redistribute it and/or
	modify it under the terms of the GNU General Public License
	as published by the Free Software Foundation; either version 2
	of the License, or (at your option) any later version.

	This program is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

	See the GNU General Public License for more details.

	You should have received a copy of the GNU General Public License
	along with this program; if not, write to:

		Free Software Foundation, Inc.
		59 Temple Place - Suite 330
		Boston, MA  02111-1307, USA

	$Id$
*/

#ifdef HAVE_CONFIG_H
# include "config.h"
#endif

#include "quakefs.h"
#include "sys.h"
#include "tga.h"

typedef struct _TargaHeader {
	unsigned char 	id_length, colormap_type, image_type;
	unsigned short	colormap_index, colormap_length;
	unsigned char	colormap_size;
	unsigned short	x_origin, y_origin, width, height;
	unsigned char	pixel_size, attributes;
} TargaHeader;


static int
fgetLittleShort (QFile *f)
{
	byte	b1, b2;

	b1 = Qgetc(f);
	b2 = Qgetc(f);

	return (short)(b1 + b2*256);
}
/*
static int
fgetLittleLong (QFile *f)
{
	byte	b1, b2, b3, b4;

	b1 = Qgetc(f);
	b2 = Qgetc(f);
	b3 = Qgetc(f);
	b4 = Qgetc(f);

	return b1 + (b2<<8) + (b3<<16) + (b4<<24);
}
*/


/*
=============
LoadTGA
=============
*/
byte *
LoadTGA (QFile *fin)
{
	int				columns, rows, numPixels;
	byte			*pixbuf;
	int				row, column;
	unsigned char	red = 0, green = 0, blue = 0, alphabyte = 0;

	TargaHeader		targa_header;
	byte			*targa_rgba;

	targa_header.id_length = Qgetc(fin);
	targa_header.colormap_type = Qgetc(fin);
	targa_header.image_type = Qgetc(fin);
	
	targa_header.colormap_index = fgetLittleShort(fin);
	targa_header.colormap_length = fgetLittleShort(fin);
	targa_header.colormap_size = Qgetc(fin);
	targa_header.x_origin = fgetLittleShort(fin);
	targa_header.y_origin = fgetLittleShort(fin);
	targa_header.width = fgetLittleShort(fin);
	targa_header.height = fgetLittleShort(fin);
	targa_header.pixel_size = Qgetc(fin);
	targa_header.attributes = Qgetc(fin);

	if (targa_header.image_type!=2 
		&& targa_header.image_type!=10) 
		Sys_Error ("LoadTGA: Only type 2 and 10 targa RGB images supported\n");

	if (targa_header.colormap_type !=0 
		|| (targa_header.pixel_size!=32 && targa_header.pixel_size!=24))
		Sys_Error ("Texture_LoadTGA: Only 32 or 24 bit images supported (no colormaps)\n");

	columns = targa_header.width;
	rows = targa_header.height;
	numPixels = columns * rows;

	targa_rgba = malloc (numPixels*4);
	
	if (targa_header.id_length != 0)
		Qseek(fin, targa_header.id_length, SEEK_CUR);  // skip TARGA image comment
	
	if (targa_header.image_type==2) {  // Uncompressed, RGB images
		for(row=rows-1; row>=0; row--) {
			pixbuf = targa_rgba + row*columns*4;
			for(column=0; column<columns; column++) {
				switch (targa_header.pixel_size) {
					case 24:
							
							blue = Qgetc(fin);
							green = Qgetc(fin);
							red = Qgetc(fin);
							*pixbuf++ = red;
							*pixbuf++ = green;
							*pixbuf++ = blue;
							*pixbuf++ = 255;
							break;
					case 32:
							blue = Qgetc(fin);
							green = Qgetc(fin);
							red = Qgetc(fin);
							alphabyte = Qgetc(fin);
							*pixbuf++ = red;
							*pixbuf++ = green;
							*pixbuf++ = blue;
							*pixbuf++ = alphabyte;
							break;
				}
			}
		}
	}
	else if (targa_header.image_type==10) {   // Runlength encoded RGB images
		unsigned char packetHeader, packetSize, j;
		for(row=rows-1; row>=0; row--) {
			pixbuf = targa_rgba + row*columns*4;
			for(column=0; column<columns; ) {
				packetHeader=Qgetc(fin);
				packetSize = 1 + (packetHeader & 0x7f);
				if (packetHeader & 0x80) {        // run-length packet
					switch (targa_header.pixel_size) {
						case 24:
								blue = Qgetc(fin);
								green = Qgetc(fin);
								red = Qgetc(fin);
								alphabyte = 255;
								break;
						case 32:
								blue = Qgetc(fin);
								green = Qgetc(fin);
								red = Qgetc(fin);
								alphabyte = Qgetc(fin);
								break;
					}
	
					for(j=0;j<packetSize;j++) {
						*pixbuf++=red;
						*pixbuf++=green;
						*pixbuf++=blue;
						*pixbuf++=alphabyte;
						column++;
						if (column==columns) { // run spans across rows
							column=0;
							if (row>0)
								row--;
							else
								goto breakOut;
							pixbuf = targa_rgba + row*columns*4;
						}
					}
				} else {                            // non run-length packet
					for(j=0;j<packetSize;j++) {
						switch (targa_header.pixel_size) {
							case 24:
									blue = Qgetc(fin);
									green = Qgetc(fin);
									red = Qgetc(fin);
									*pixbuf++ = red;
									*pixbuf++ = green;
									*pixbuf++ = blue;
									*pixbuf++ = 255;
									break;
							case 32:
									blue = Qgetc(fin);
									green = Qgetc(fin);
									red = Qgetc(fin);
									alphabyte = Qgetc(fin);
									*pixbuf++ = red;
									*pixbuf++ = green;
									*pixbuf++ = blue;
									*pixbuf++ = alphabyte;
									break;
						}
						column++;
						if (column==columns) { // pixel packet run spans across rows
							column=0;
							if (row>0)
								row--;
							else
								goto breakOut;
							pixbuf = targa_rgba + row*columns*4;
						}						
					}
				}
			}
			breakOut:;
		}
	}
	
	Qclose(fin);
	return targa_rgba;
}