/*
===========================================================================
Copyright (C) 1999-2005 Id Software, Inc.
Copyright (C) 2006 Robert Beckebans <trebor_7@users.sourceforge.net>

This file is part of XreaL source code.

XreaL source code 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.

XreaL source code 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 XreaL source code; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
===========================================================================
*/
//
// l3dslib.c: library for loading triangles from an Alias triangle file
//

#include <stdio.h>
#include "cmdlib.h"
#include "mathlib.h"
#include "trilib.h"
#include "l3dslib.h"

#define MAIN3DS       0x4D4D
#define EDIT3DS       0x3D3D	// this is the start of the editor config
#define EDIT_OBJECT   0x4000
#define OBJ_TRIMESH   0x4100
#define TRI_VERTEXL   0x4110
#define TRI_FACEL1    0x4120

#define MAXVERTS	2000
#define MAXTRIANGLES	750

typedef struct
{
	int             v[4];
} tri;

float           fverts[MAXVERTS][3];
tri             tris[MAXTRIANGLES];

int             bytesread, level, numtris, totaltris;
int             vertsfound, trisfound;

triangle_t     *ptri;


// Alias stores triangles as 3 explicit vertices in .tri files, so even though we
// start out with a vertex pool and vertex indices for triangles, we have to convert
// to raw, explicit triangles
void StoreAliasTriangles(void)
{
	int             i, j, k;

	if((totaltris + numtris) > MAXTRIANGLES)
		Error("Error: Too many triangles");

	for(i = 0; i < numtris; i++)
	{
		for(j = 0; j < 3; j++)
		{
			for(k = 0; k < 3; k++)
			{
				ptri[i + totaltris].verts[j][k] = fverts[tris[i].v[j]][k];
			}
		}
	}

	totaltris += numtris;
	numtris = 0;
	vertsfound = 0;
	trisfound = 0;
}


int ParseVertexL(FILE * input)
{
	int             i, j, startbytesread, numverts;
	unsigned short  tshort;

	if(vertsfound)
		Error("Error: Multiple vertex chunks");

	vertsfound = 1;
	startbytesread = bytesread;

	if(feof(input))
		Error("Error: unexpected end of file");

	fread(&tshort, sizeof(tshort), 1, input);
	bytesread += sizeof(tshort);
	numverts = (int)tshort;

	if(numverts > MAXVERTS)
		Error("Error: Too many vertices");

	for(i = 0; i < numverts; i++)
	{
		for(j = 0; j < 3; j++)
		{
			if(feof(input))
				Error("Error: unexpected end of file");

			fread(&fverts[i][j], sizeof(float), 1, input);
			bytesread += sizeof(float);
		}
	}

	if(vertsfound && trisfound)
		StoreAliasTriangles();

	return bytesread - startbytesread;
}


int ParseFaceL1(FILE * input)
{

	int             i, j, startbytesread;
	unsigned short  tshort;

	if(trisfound)
		Error("Error: Multiple face chunks");

	trisfound = 1;
	startbytesread = bytesread;

	if(feof(input))
		Error("Error: unexpected end of file");

	fread(&tshort, sizeof(tshort), 1, input);
	bytesread += sizeof(tshort);
	numtris = (int)tshort;

	if(numtris > MAXTRIANGLES)
		Error("Error: Too many triangles");

	for(i = 0; i < numtris; i++)
	{
		for(j = 0; j < 4; j++)
		{
			if(feof(input))
				Error("Error: unexpected end of file");

			fread(&tshort, sizeof(tshort), 1, input);
			bytesread += sizeof(tshort);
			tris[i].v[j] = (int)tshort;
		}
	}

	if(vertsfound && trisfound)
		StoreAliasTriangles();

	return bytesread - startbytesread;
}


int ParseChunk(FILE * input)
{
#define BLOCK_SIZE	4096
	char            temp[BLOCK_SIZE];
	unsigned short  type;
	int             i, length, w, t, retval;

	level++;
	retval = 0;

// chunk type
	if(feof(input))
		Error("Error: unexpected end of file");

	fread(&type, sizeof(type), 1, input);
	bytesread += sizeof(type);

// chunk length
	if(feof(input))
		Error("Error: unexpected end of file");

	fread(&length, sizeof(length), 1, input);
	bytesread += sizeof(length);
	w = length - 6;

// process chunk if we care about it, otherwise skip it
	switch (type)
	{
		case TRI_VERTEXL:
			w -= ParseVertexL(input);
			goto ParseSubchunk;

		case TRI_FACEL1:
			w -= ParseFaceL1(input);
			goto ParseSubchunk;

		case EDIT_OBJECT:
			// read the name
			i = 0;

			do
			{
				if(feof(input))
					Error("Error: unexpected end of file");

				fread(&temp[i], 1, 1, input);
				i++;
				w--;
				bytesread++;
			} while(temp[i - 1]);

		case MAIN3DS:
		case OBJ_TRIMESH:
		case EDIT3DS:
			// parse through subchunks
		  ParseSubchunk:
			while(w > 0)
			{
				w -= ParseChunk(input);
			}

			retval = length;
			goto Done;

		default:
			// skip other chunks
			while(w > 0)
			{
				t = w;

				if(t > BLOCK_SIZE)
					t = BLOCK_SIZE;

				if(feof(input))
					Error("Error: unexpected end of file");

				fread(&temp, t, 1, input);
				bytesread += t;

				w -= t;
			}

			retval = length;
			goto Done;
	}

  Done:
	level--;
	return retval;
}


void Load3DSTriangleList(char *filename, triangle_t ** pptri, int *numtriangles)
{
	FILE           *input;
	short int       tshort;

	bytesread = 0;
	level = 0;
	numtris = 0;
	totaltris = 0;
	vertsfound = 0;
	trisfound = 0;

	if((input = fopen(filename, "rb")) == 0)
	{
		fprintf(stderr, "reader: could not open file '%s'\n", filename);
		exit(0);
	}

	fread(&tshort, sizeof(tshort), 1, input);

// should only be MAIN3DS, but some files seem to start with EDIT3DS, with
// no MAIN3DS
	if((tshort != MAIN3DS) && (tshort != EDIT3DS))
	{
		fprintf(stderr, "File is not a 3DS file.\n");
		exit(0);
	}

// back to top of file so we can parse the first chunk descriptor
	fseek(input, 0, SEEK_SET);

	ptri = safe_malloc(MAXTRIANGLES * sizeof(triangle_t));

	*pptri = ptri;

// parse through looking for the relevant chunk tree (MAIN3DS | EDIT3DS | EDIT_OBJECT |
// OBJ_TRIMESH | {TRI_VERTEXL, TRI_FACEL1}) and skipping other chunks
	ParseChunk(input);

	if(vertsfound || trisfound)
		Error("Incomplete triangle set");

	*numtriangles = totaltris;

	fclose(input);
}
