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flightgear/FixObj/obj.c
curt 9cc98181fa Code now calculates a center reference points and outputs everything 
relative to that.  This is useful in the rendering engine to keep everything
close to (0, 0, 0) where we can avoid many GLfloat precision problems.
1998-04-27 03:33:11 +00:00

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/**************************************************************************
* obj.c -- routines to handle WaveFront .obj format files.
*
* Written by Curtis Olson, started October 1997.
*
* Copyright (C) 1997 Curtis L. Olson - curt@infoplane.com
*
* 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 the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*
* $Id$
* (Log is kept at end of this file)
**************************************************************************/
#include <stdio.h>
#include <string.h>
#include "obj.h"
#include <Math/mat3.h>
/* what do ya' know, here's some global variables */
static double nodes[MAXNODES][3];
static double normals[MAXNODES][3];
static int faces[MAXNODES][3];
int ncount, vncount, fcount;
static int ccw_list[MAXNODES];
int ccw_list_ptr;
static int cw_list[MAXNODES];
int cw_list_ptr;
FILE *in, *out;
double refx, refy, refz;
/* some simple list routines */
/* reset the list */
void list_init(int *list_ptr) {
*list_ptr = 0;
}
/* add to list */
void list_add(int *list, int *list_ptr, int node) {
if ( *list_ptr >= MAXNODES ) {
printf("ERROR: list overflow in list_add()\n");
exit(-1);
}
list[*list_ptr] = node;
*list_ptr += 1;
/* printf("list pointer = %d adding %d\n", *list_ptr, node); */
}
/* dump nodes */
void dump_nodes( void ) {
int i;
fprintf(out, "\n");
for ( i = 0; i < ncount; i++ ) {
fprintf(out, "v %.4lf %.4lf %.4lf\n",
nodes[i][0] - refx, nodes[i][1] - refy, nodes[i][2] - refz);
}
}
/* dump normals */
void dump_normals( void ) {
int i;
fprintf(out, "\n");
for ( i = 0; i < vncount; i++ ) {
fprintf(out, "vn %.4lf %.4lf %.4lf\n",
normals[i][0], normals[i][1], normals[i][2]);
}
}
/* dump faces */
void dump_faces( void ) {
int i;
fprintf(out, "\n");
for ( i = 0; i < fcount; i++ ) {
fprintf(out, "f %d %d %d\n",
faces[i][0], faces[i][1], faces[i][2]);
}
}
/* dump list */
void dump_list(int *list, int list_ptr) {
int i;
if ( list_ptr < 3 ) {
printf("List is empty ... skipping\n");
return;
}
printf("Dumping list, size = %d\n", list_ptr);
i = 0;
while ( i < list_ptr ) {
/* do next strip */
/* dump header */
fprintf(out, "t %d %d %d\n", list[i], list[i+1], list[i+2]);
/* printf("t %d %d %d\n", list[i], list[i+1], list[i+2]); */
i += 3;
/* dump rest of strip (until -1) */
while ( (i < list_ptr) && (list[i] != -1) ) {
fprintf(out, "q %d", list[i]);
i++;
if ( (i < list_ptr) && (list[i] != -1) ) {
fprintf(out, " %d", list[i]);
i++;
}
fprintf(out, "\n");
}
i++;
}
}
/* Check the direction the current triangle faces, compared to it's
* pregenerated normal. Returns the dot product between the target
* normal and actual normal. If the dot product is close to 1.0, they
* nearly match. If the are close to -1.0, the are nearly
* opposite. */
double check_cur_face(int n1, int n2, int n3) {
double v1[3], v2[3], approx_normal[3], dot_prod, temp;
/* check for the proper rotation by calculating an approximate
* normal and seeing if it is close to the precalculated normal */
v1[0] = nodes[n2][0] - nodes[n1][0];
v1[1] = nodes[n2][1] - nodes[n1][1];
v1[2] = nodes[n2][2] - nodes[n1][2];
v2[0] = nodes[n3][0] - nodes[n1][0];
v2[1] = nodes[n3][1] - nodes[n1][1];
v2[2] = nodes[n3][2] - nodes[n1][2];
MAT3cross_product(approx_normal, v1, v2);
MAT3_NORMALIZE_VEC(approx_normal,temp);
dot_prod = MAT3_DOT_PRODUCT(normals[n1], approx_normal);
/* not first triangle */
/* if ( ((dot_prod < -0.5) && !is_backwards) ||
((dot_prod > 0.5) && is_backwards) ) {
printf(" Approx normal = %.2f %.2f %.2f\n", approx_normal[0],
approx_normal[1], approx_normal[2]);
printf(" Dot product = %.4f\n", dot_prod);
} */
/* angle = acos(dot_prod); */
/* printf("Normal ANGLE = %.3f rads.\n", angle); */
return(dot_prod);
}
/* Load a .obj file */
void obj_fix(char *infile, char *outfile) {
char line[256];
double dot_prod;
int first, n1, n2, n3, n4;
double x, y, z, xmax, xmin, ymax, ymin, zmax, zmin;
int is_ccw;
if ( (in = fopen(infile, "r")) == NULL ) {
printf("Cannot open file: %s\n", infile);
exit(-1);
}
if ( (out = fopen(outfile, "w")) == NULL ) {
printf("Cannot open file: %s\n", outfile);
exit(-1);
}
list_init(&ccw_list_ptr);
list_init(&cw_list_ptr);
first = 1;
ncount = 0;
vncount = 0;
fcount = 0;
printf("Reading file: %s\n", infile);
while ( fgets(line, 250, in) != NULL ) {
if ( line[0] == '#' ) {
/* pass along the comments verbatim */
fprintf(out, "%s", line);
} else if ( strlen(line) <= 1 ) {
/* don't pass along empty lines */
// fprintf(out, "%s", line);
} else if ( strncmp(line, "v ", 2) == 0 ) {
/* save vertex to memory and output to file */
if ( ncount < MAXNODES ) {
/* printf("vertex = %s", line); */
sscanf(line, "v %lf %lf %lf\n", &x, &y, &z);
nodes[ncount][0] = x;
nodes[ncount][1] = y;
nodes[ncount][2] = z;
/* first time through set min's and max'es */
if ( ncount == 1 ) {
xmin = x;
xmax = x;
ymin = y;
ymax = y;
zmin = z;
zmax = z;
}
/* keep track of min/max vertex values */
if ( x < xmin ) xmin = x;
if ( x > xmax ) xmax = x;
if ( y < ymin ) ymin = y;
if ( y > ymax ) ymax = y;
if ( z < zmin ) zmin = z;
if ( z > zmax ) zmax = z;
// fprintf(out, "v %.2f %.2f %.2f\n",
// nodes[ncount][0], nodes[ncount][1], nodes[ncount][2]);
ncount++;
} else {
printf("Read too many nodes ... dying :-(\n");
exit(-1);
}
} else if ( strncmp(line, "vn ", 3) == 0 ) {
/* save vertex normals to memory and output to file */
if ( vncount < MAXNODES ) {
/* printf("vertex normal = %s", line); */
sscanf(line, "vn %lf %lf %lf\n",
&normals[vncount][0], &normals[vncount][1],
&normals[vncount][2]);
// fprintf(out, "vn %.4f %.4f %.4f\n", normals[vncount][0],
// normals[vncount][1], normals[vncount][2]);
vncount++;
} else {
printf("Read too many vertex normals ... dying :-(\n");
exit(-1);
}
} else if ( line[0] == 't' ) {
/* starting a new triangle strip */
printf("Starting a new triangle strip\n");
n1 = n2 = n3 = n4 = 0;
printf("new tri strip = %s", line);
sscanf(line, "t %d %d %d %d\n", &n1, &n2, &n3, &n4);
/* special cases to handle bugs in our beloved tri striper */
if ( (n1 == 4) && (n2 == 2) && (n3 == 2) && (n4 == 1) ) {
n2 = 3;
}
if ( (n1 == 3) && (n2 == 1) && (n3 == 1) && (n4 == 0) ) {
n3 = 4;
}
dot_prod = check_cur_face(n1, n2, n3);
if ( dot_prod < 0.0 ) {
/* this stripe is backwards (CW) */
is_ccw = 0;
printf(" -> Starting a backwards stripe\n");
} else {
/* this stripe is normal (CCW) */
is_ccw = 1;
}
if ( is_ccw ) {
if ( ccw_list_ptr ) {
list_add(ccw_list, &ccw_list_ptr, -1);
}
list_add(ccw_list, &ccw_list_ptr, n1);
list_add(ccw_list, &ccw_list_ptr, n2);
list_add(ccw_list, &ccw_list_ptr, n3);
} else {
if ( cw_list_ptr ) {
list_add(cw_list, &cw_list_ptr, -1);
}
list_add(cw_list, &cw_list_ptr, n1);
list_add(cw_list, &cw_list_ptr, n2);
list_add(cw_list, &cw_list_ptr, n3);
}
if ( n4 > 0 ) {
if ( is_ccw ) {
list_add(ccw_list, &ccw_list_ptr, n4);
} else {
list_add(cw_list, &cw_list_ptr, n4);
}
}
} else if ( line[0] == 'f' ) {
if ( fcount < MAXNODES ) {
/* pass along the unoptimized faces verbatim */
sscanf(line, "f %d %d %d\n", &n1, &n2, &n3);
faces[fcount][0] = n1;
faces[fcount][1] = n2;
faces[fcount][2] = n3;
fcount++;
} else {
printf("Read too many unoptimized faces ... dying :-(\n");
exit(-1);
}
// fprintf(out, "%s", line);
} else if ( line[0] == 'q' ) {
/* continue a triangle strip */
n1 = n2 = 0;
/* printf("continued tri strip = %s ", line); */
sscanf(line, "q %d %d\n", &n1, &n2);
if ( is_ccw ) {
list_add(ccw_list, &ccw_list_ptr, n1);
} else {
list_add(cw_list, &cw_list_ptr, n1);
}
if ( n2 > 0 ) {
if ( is_ccw ) {
list_add(ccw_list, &ccw_list_ptr, n2);
} else {
list_add(cw_list, &cw_list_ptr, n2);
}
}
} else {
printf("Unknown line in %s = %s\n", infile, line);
}
}
/* reference point is the "center" */
refx = (xmin + xmax) / 2.0;
refy = (ymin + ymax) / 2.0;
refz = (zmin + zmax) / 2.0;
fprintf(out, "\n");
fprintf(out, "ref %.2f %.2f %.2f\n", refx, refy, refz);
dump_nodes();
dump_normals();
dump_faces();
fprintf(out, "winding ccw\n");
dump_list(ccw_list, ccw_list_ptr);
fprintf(out, "winding cw\n");
dump_list(cw_list, cw_list_ptr);
fclose(in);
fclose(out);
}
/* $Log$
/* Revision 1.10 1998/04/27 03:33:11 curt
/* Code now calculates a center reference points and outputs everything
/* relative to that. This is useful in the rendering engine to keep everything
/* close to (0, 0, 0) where we can avoid many GLfloat precision problems.
/*
* Revision 1.9 1998/04/18 04:01:03 curt
* Now use libMath rather than having local copies of math routines.
*
* Revision 1.8 1998/04/08 23:19:37 curt
* Adopted Gnu automake/autoconf system.
*
* Revision 1.7 1998/03/19 02:51:41 curt
* Added special case handling to compensate for bugs in our beloved tri striper
*
* Revision 1.6 1998/03/03 15:36:12 curt
* Tweaks for compiling with g++
*
* Revision 1.5 1998/03/03 03:37:03 curt
* Cumulative tweaks.
*
* Revision 1.4 1998/01/31 00:41:25 curt
* Made a few changes converting floats to doubles.
*
* Revision 1.3 1998/01/19 19:51:07 curt
* A couple final pre-release tweaks.
*
* Revision 1.2 1998/01/09 23:03:12 curt
* Restructured to split 1deg x 1deg dem's into 64 subsections.
*
* Revision 1.1 1997/12/08 19:28:54 curt
* Initial revision.
*
*/
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