280 lines
7.4 KiB
C
280 lines
7.4 KiB
C
/* tri2obj.c -- read in a .ele/.node file pair generated by the triangle
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* program and output a simple Wavefront .obj file.
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*
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* Written by Curtis Olson, started October 1997.
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*
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* Copyright (C) 1997 Curtis L. Olson - curt@infoplane.com
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*
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* $Id$
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* (Log is kept at end of this file)
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*/
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#include <stdio.h>
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#include <string.h>
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#include "tri2obj.h"
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#include "../../Src/constants.h"
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#include "../../Src/types.h"
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#include "../../Src/Math/fg_geodesy.h"
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#include "../../Src/Math/mat3.h"
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#include "../../Src/Math/polar.h"
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int nodecount, tricount;
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struct fgCartesianPoint nodes[MAX_NODES];
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int tris[MAX_TRIS][3];
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int new_tris[MAX_TRIS][3];
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/* convert a geodetic point lon(arcsec), lat(arcsec), elev(meter) to
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* a cartesian point */
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struct fgCartesianPoint geod_to_cart(double geod[3]) {
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struct fgCartesianPoint p;
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double gc_lon, gc_lat, sl_radius;
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/* printf("A geodetic point is (%.2f, %.2f, %.2f)\n",
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geod[0], geod[1], geod[2]); */
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gc_lon = geod[0]*ARCSEC_TO_RAD;
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fgGeodToGeoc(geod[1]*ARCSEC_TO_RAD, geod[2], &sl_radius, &gc_lat);
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/* printf("A geocentric point is (%.2f, %.2f, %.2f)\n", gc_lon,
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gc_lat, sl_radius+geod[2]); */
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p = fgPolarToCart(gc_lon, gc_lat, sl_radius+geod[2]);
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/* printf("A cart point is (%.8f, %.8f, %.8f)\n", p.x, p.y, p.z); */
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return(p);
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}
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/* given three points defining a triangle, calculate the normal */
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void calc_normal(struct fgCartesianPoint p1, struct fgCartesianPoint p2,
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struct fgCartesianPoint p3, double normal[3])
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{
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double v1[3], v2[3];
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float temp;
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v1[0] = p2.x - p1.x; v1[1] = p2.y - p1.y; v1[2] = p2.z - p1.z;
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v2[0] = p3.x - p1.x; v2[1] = p3.y - p1.y; v2[2] = p3.z - p1.z;
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MAT3cross_product(normal, v1, v2);
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MAT3_NORMALIZE_VEC(normal,temp);
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/* printf(" Normal = %.2f %.2f %.2f\n", normal[0], normal[1], normal[2]); */
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}
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/* return the index of all triangles containing the specified node */
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void find_tris(int n, int *t1, int *t2, int *t3) {
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int i;
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*t1 = *t2 = *t3 = 0;
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i = 1;
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while ( i <= tricount ) {
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if ( (n == tris[i][0]) || (n == tris[i][1]) || (n == tris[i][2]) ) {
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if ( *t1 == 0 ) {
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*t1 = i;
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} else if ( *t2 == 0 ) {
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*t2 = i;
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} else {
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*t3 = i;
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}
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}
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i++;
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}
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}
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/* Initialize a new mesh structure */
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void triload(char *basename) {
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char nodename[256], elename[256];
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double n[3];
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FILE *node, *ele;
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int dim, junk1, junk2;
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int i;
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strcpy(nodename, basename);
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strcat(nodename, ".node");
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strcpy(elename, basename);
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strcat(elename, ".ele");
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printf("Loading node file: %s ...\n", nodename);
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if ( (node = fopen(nodename, "r")) == NULL ) {
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printf("Cannot open file '%s'\n", nodename);
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exit(-1);
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}
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fscanf(node, "%d %d %d %d", &nodecount, &dim, &junk1, &junk2);
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if ( nodecount > MAX_NODES - 1 ) {
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printf("Error, too many nodes, need to increase array size\n");
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exit(-1);
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} else {
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printf(" Expecting %d nodes\n", nodecount);
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}
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for ( i = 1; i <= nodecount; i++ ) {
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fscanf(node, "%d %lf %lf %lf %d\n", &junk1,
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&n[0], &n[1], &n[2], &junk2);
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/* printf("%d %.2f %.2f %.2f\n", junk1, n[0], n[1], n[2]); */
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nodes[i] = geod_to_cart(n);
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/* printf("%d %.2f %.2f %.2f\n",
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junk1, nodes[i].x, nodes[i].y, nodes[i].z); */
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}
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fclose(node);
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printf("Loading element file: %s ...\n", elename);
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if ( (ele = fopen(elename, "r")) == NULL ) {
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printf("Cannot open file '%s'\n", elename);
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exit(-1);
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}
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fscanf(ele, "%d %d %d", &tricount, &junk1, &junk2);
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if ( tricount > MAX_TRIS - 1 ) {
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printf("Error, too many elements, need to increase array size\n");
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exit(-1);
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} else {
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printf(" Expecting %d elements\n", tricount);
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}
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for ( i = 1; i <= tricount; i++ ) {
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fscanf(ele, "%d %d %d %d\n", &junk1,
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&tris[i][0], &tris[i][1], &tris[i][2]);
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/* printf("%d %d %d %d\n", junk1, tris[i][0], tris[i][1], tris[i][2]);*/
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}
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fclose(ele);
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}
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/* dump in WaveFront .obj format */
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void dump_obj(char *basename) {
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char objname[256];
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double n1[3], n2[3], n3[3], norm[3], temp;
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FILE *obj;
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int i, t1, t2, t3, count;
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strcpy(objname, basename);
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strcat(objname, ".obj");
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printf("Dumping to file: %s ...\n", objname);
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obj = fopen(objname, "w");
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/* dump vertices */
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printf(" writing vertices\n");
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for ( i = 1; i <= nodecount; i++ ) {
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fprintf(obj, "v %.2f %.2f %.2f\n",
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nodes[i].x, nodes[i].y, nodes[i].z);
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}
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printf(" calculating and writing normals\n");
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/* calculate and generate normals */
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for ( i = 1; i <= nodecount; i++ ) {
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/* printf("Finding normal\n"); */
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find_tris(i, &t1, &t2, &t3);
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n1[0] = n1[1] = n1[2] = 0.0;
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n2[0] = n2[1] = n2[2] = 0.0;
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n3[0] = n3[1] = n3[2] = 0.0;
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count = 1;
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calc_normal(nodes[tris[t1][0]], nodes[tris[t1][1]], nodes[tris[t1][2]],
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n1);
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if ( t2 > 0 ) {
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calc_normal(nodes[tris[t2][0]], nodes[tris[t2][1]],
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nodes[tris[t2][2]], n2);
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count = 2;
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}
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if ( t3 > 0 ) {
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calc_normal(nodes[tris[t3][0]], nodes[tris[t3][1]],
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nodes[tris[t3][2]], n3);
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count = 3;
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}
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/* printf(" norm[2] = %.2f %.2f %.2f\n", n1[2], n2[2], n3[2]); */
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norm[0] = ( n1[0] + n2[0] + n3[0] ) / (double)count;
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norm[1] = ( n1[1] + n2[1] + n3[1] ) / (double)count;
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norm[2] = ( n1[2] + n2[2] + n3[2] ) / (double)count;
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/* printf(" count = %d\n", count); */
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/* printf(" Ave. normal = %.4f %.4f %.4f\n", norm[0], norm[1], norm[2]);*/
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MAT3_NORMALIZE_VEC(norm, temp);
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/* printf(" Normalized ave. normal = %.4f %.4f %.4f\n", */
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/* norm[0], norm[1], norm[2]); */
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fprintf(obj, "vn %.4f %.4f %.4f\n", norm[0], norm[1], norm[2]);
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}
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/* dump faces */
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printf(" writing faces\n");
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for ( i = 1; i <= tricount; i++ ) {
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fprintf(obj, "f %d//%d %d//%d %d//%d\n",
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tris[i][0], tris[i][0],
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tris[i][1], tris[i][1],
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tris[i][2], tris[i][2]);
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}
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fclose(obj);
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}
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int main(int argc, char **argv) {
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char basename[256];
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strcpy(basename, argv[1]);
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/* load the input data files */
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triload(basename);
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/* dump in WaveFront .obj format */
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dump_obj(basename);
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return(0);
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}
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/* $Log$
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/* Revision 1.5 1997/12/08 19:17:50 curt
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/* Fixed a type in the normal generation code.
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/*
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* Revision 1.4 1997/12/02 13:13:32 curt
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* Fixed problem with averaged vertex normals.
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*
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* Revision 1.3 1997/11/15 18:05:05 curt
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* minor tweaks ...
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*
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* Revision 1.2 1997/11/14 00:29:13 curt
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* Transform scenery coordinates at this point in pipeline when scenery is
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* being translated to .obj format, not when it is being loaded into the end
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* renderer. Precalculate normals for each node as average of the normals
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* of each containing polygon so Garoude shading is now supportable.
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*
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* Revision 1.1 1997/10/29 23:05:15 curt
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* Initial revision.
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*
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*/
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