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flightgear/Scenery/obj.c
curt e20b2023dc Worked on winding problem without luck, so back to calling glFrontFace() 
3 times for each scenery area.
1997-12-30 23:09:40 +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)
**************************************************************************/
#ifdef WIN32
# include <windows.h>
#endif
#include <stdio.h>
#include <string.h>
#include <GL/glut.h>
#include "../XGL/xgl.h"
#include "obj.h"
#include "scenery.h"
#include "../Math/mat3.h"
#define MAXNODES 100000
float nodes[MAXNODES][3];
float normals[MAXNODES][3];
/* given three points defining a triangle, calculate the normal */
void calc_normal(float p1[3], float p2[3], float p3[3], double normal[3])
{
double v1[3], v2[3];
float temp;
v1[0] = p2[0] - p1[0]; v1[1] = p2[1] - p1[1]; v1[2] = p2[2] - p1[2];
v2[0] = p3[0] - p1[0]; v2[1] = p3[1] - p1[1]; v2[2] = p3[2] - p1[2];
MAT3cross_product(normal, v1, v2);
MAT3_NORMALIZE_VEC(normal,temp);
/* printf(" Normal = %.2f %.2f %.2f\n", normal[0], normal[1], normal[2]);*/
}
/* Load a .obj file and generate the GL call list */
GLint fgObjLoad(char *path) {
char line[256], winding_str[256];
double v1[3], v2[3], approx_normal[3], normal[3], dot_prod, scale, temp;
struct fgCartesianPoint ref;
GLint area;
FILE *f;
int first, ncount, vncount, n1, n2, n3, n4;
static int use_vertex_norms = 1;
int i, winding;
int last1, last2, odd;
if ( (f = fopen(path, "r")) == NULL ) {
printf("Cannot open file: %s\n", path);
exit(-1);
}
area = xglGenLists(1);
xglNewList(area, GL_COMPILE);
first = 1;
ncount = 1;
vncount = 1;
while ( fgets(line, 250, f) != NULL ) {
if ( line[0] == '#' ) {
/* comment -- ignore */
} else if ( line[0] == '\n' ) {
/* empty line -- ignore */
} else if ( strncmp(line, "v ", 2) == 0 ) {
/* node (vertex) */
if ( ncount < MAXNODES ) {
/* printf("vertex = %s", line); */
sscanf(line, "v %f %f %f\n",
&nodes[ncount][0], &nodes[ncount][1], &nodes[ncount][2]);
if ( ncount == 1 ) {
/* first node becomes the reference point */
ref.x = nodes[ncount][0];
ref.y = nodes[ncount][1];
ref.z = nodes[ncount][2];
scenery.center = ref;
}
ncount++;
} else {
printf("Read too many nodes ... dying :-(\n");
exit(-1);
}
} else if ( strncmp(line, "vn ", 3) == 0 ) {
/* vertex normal */
if ( vncount < MAXNODES ) {
/* printf("vertex normal = %s", line); */
sscanf(line, "vn %f %f %f\n",
&normals[vncount][0], &normals[vncount][1],
&normals[vncount][2]);
vncount++;
} else {
printf("Read too many vertex normals ... dying :-(\n");
exit(-1);
}
} else if ( strncmp(line, "winding ", 8) == 0 ) {
sscanf(line+8, "%s", winding_str);
printf(" WINDING = %s\n", winding_str);
/* can't call xglFrontFace() between xglBegin() & xglEnd() */
xglEnd();
first = 1;
if ( strcmp(winding_str, "cw") == 0 ) {
xglFrontFace( GL_CW );
winding = 0;
} else {
glFrontFace ( GL_CCW );
winding = 1;
}
} else if ( line[0] == 't' ) {
/* start a new triangle strip */
n1 = n2 = n3 = n4 = 0;
if ( !first ) {
/* close out the previous structure and start the next */
xglEnd();
} else {
first = 0;
}
/* printf(" new tri strip = %s", line); */
sscanf(line, "t %d %d %d %d\n", &n1, &n2, &n3, &n4);
/* printf("(t) = "); */
xglBegin(GL_TRIANGLE_STRIP);
if ( winding ) {
odd = 1;
scale = 1.0;
} else {
odd = 0;
scale = 1.0;
}
if ( use_vertex_norms ) {
MAT3_SCALE_VEC(normal, normals[n1], scale);
xglNormal3dv(normal);
xglVertex3d(nodes[n1][0] - ref.x, nodes[n1][1] - ref.y,
nodes[n1][2] - ref.z);
MAT3_SCALE_VEC(normal, normals[n2], scale);
xglNormal3dv(normal);
xglVertex3d(nodes[n2][0] - ref.x, nodes[n2][1] - ref.y,
nodes[n2][2] - ref.z);
MAT3_SCALE_VEC(normal, normals[n3], scale);
xglNormal3dv(normal);
xglVertex3d(nodes[n3][0] - ref.x, nodes[n3][1] - ref.y,
nodes[n3][2] - ref.z);
} else {
if ( odd ) {
calc_normal(nodes[n1], nodes[n2], nodes[n3], approx_normal);
} else {
calc_normal(nodes[n2], nodes[n1], nodes[n3], approx_normal);
}
MAT3_SCALE_VEC(normal, approx_normal, scale);
xglNormal3dv(normal);
xglVertex3d(nodes[n1][0] - ref.x, nodes[n1][1] - ref.y,
nodes[n1][2] - ref.z);
xglVertex3d(nodes[n2][0] - ref.x, nodes[n2][1] - ref.y,
nodes[n2][2] - ref.z);
xglVertex3d(nodes[n3][0] - ref.x, nodes[n3][1] - ref.y,
nodes[n3][2] - ref.z);
}
odd = 1 - odd;
last1 = n2;
last2 = n3;
if ( n4 > 0 ) {
if ( use_vertex_norms ) {
MAT3_SCALE_VEC(normal, normals[n4], scale);
} else {
calc_normal(nodes[n3], nodes[n2], nodes[n4], approx_normal);
MAT3_SCALE_VEC(normal, approx_normal, scale);
}
xglNormal3dv(normal);
xglVertex3d(nodes[n4][0] - ref.x, nodes[n4][1] - ref.y,
nodes[n4][2] - ref.z);
odd = 1 - odd;
last1 = n3;
last2 = n4;
}
} else if ( line[0] == 'f' ) {
/* unoptimized face */
if ( !first ) {
/* close out the previous structure and start the next */
xglEnd();
} else {
first = 0;
}
xglBegin(GL_TRIANGLES);
/* printf("new triangle = %s", line);*/
sscanf(line, "f %d %d %d\n", &n1, &n2, &n3);
xglNormal3d(normals[n1][0], normals[n1][1], normals[n1][2]);
xglVertex3d(nodes[n1][0] - ref.x, nodes[n1][1] - ref.y,
nodes[n1][2] - ref.z);
xglNormal3d(normals[n2][0], normals[n2][1], normals[n2][2]);
xglVertex3d(nodes[n2][0] - ref.x, nodes[n2][1] - ref.y,
nodes[n2][2] - ref.z);
xglNormal3d(normals[n3][0], normals[n3][1], normals[n3][2]);
xglVertex3d(nodes[n3][0] - ref.x, nodes[n3][1] - ref.y,
nodes[n3][2] - ref.z);
} 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);
/* printf("read %d %d\n", n1, n2); */
if ( use_vertex_norms ) {
MAT3_SCALE_VEC(normal, normals[n1], scale);
xglNormal3dv(normal);
} else {
if ( odd ) {
calc_normal(nodes[last1], nodes[last2], nodes[n1],
approx_normal);
} else {
calc_normal(nodes[last2], nodes[last1], nodes[n1],
approx_normal);
}
MAT3_SCALE_VEC(normal, approx_normal, scale);
xglNormal3dv(normal);
}
xglVertex3d(nodes[n1][0] - ref.x, nodes[n1][1] - ref.y,
nodes[n1][2] - ref.z);
odd = 1 - odd;
last1 = last2;
last2 = n1;
if ( n2 > 0 ) {
/* printf(" (cont)\n"); */
if ( use_vertex_norms ) {
MAT3_SCALE_VEC(normal, normals[n2], scale);
xglNormal3dv(normal);
} else {
if ( odd ) {
calc_normal(nodes[last1], nodes[last2], nodes[n2],
approx_normal);
} else {
calc_normal(nodes[last2], nodes[last1], nodes[n2],
approx_normal);
}
MAT3_SCALE_VEC(normal, approx_normal, scale);
xglNormal3dv(normal);
}
xglVertex3d(nodes[n2][0] - ref.x, nodes[n2][1] - ref.y,
nodes[n2][2] - ref.z);
odd = 1 -odd;
last1 = last2;
last2 = n2;
}
} else {
printf("Unknown line in %s = %s\n", path, line);
}
}
xglEnd();
/* Draw normal vectors (for visually verifying normals)*/
/*
xglBegin(GL_LINES);
xglColor3f(0.0, 0.0, 0.0);
for ( i = 0; i < ncount; i++ ) {
xglVertex3d(nodes[i][0] - ref.x,
nodes[i][1] - ref.y,
nodes[i][2] - ref.z);
xglVertex3d(nodes[i][0] - ref.x + 500*normals[i][0],
nodes[i][1] - ref.y + 500*normals[i][1],
nodes[i][2] - ref.z + 500*normals[i][2]);
}
xglEnd();
*/
xglFrontFace ( GL_CCW );
xglEndList();
fclose(f);
return(area);
}
/* $Log$
/* Revision 1.16 1997/12/30 23:09:40 curt
/* Worked on winding problem without luck, so back to calling glFrontFace()
/* 3 times for each scenery area.
/*
* Revision 1.15 1997/12/30 20:47:51 curt
* Integrated new event manager with subsystem initializations.
*
* Revision 1.14 1997/12/30 01:38:46 curt
* Switched back to per vertex normals and smooth shading for terrain.
*
* Revision 1.13 1997/12/18 23:32:36 curt
* First stab at sky dome actually starting to look reasonable. :-)
*
* Revision 1.12 1997/12/17 23:13:47 curt
* Began working on rendering the sky.
*
* Revision 1.11 1997/12/15 23:55:01 curt
* Add xgl wrappers for debugging.
* Generate terrain normals on the fly.
*
* Revision 1.10 1997/12/12 21:41:28 curt
* More light/material property tweaking ... still a ways off.
*
* Revision 1.9 1997/12/12 19:52:57 curt
* Working on lightling and material properties.
*
* Revision 1.8 1997/12/10 01:19:51 curt
* Tweaks for verion 0.15 release.
*
* Revision 1.7 1997/12/08 22:51:17 curt
* Enhanced to handle ccw and cw tri-stripe winding. This is a temporary
* admission of defeat. I will eventually go back and get all the stripes
* wound the same way (ccw).
*
* Revision 1.6 1997/11/25 19:25:35 curt
* Changes to integrate Durk's moon/sun code updates + clean up.
*
* Revision 1.5 1997/11/15 18:16:39 curt
* minor tweaks.
*
* Revision 1.4 1997/11/14 00:26:49 curt
* Transform scenery coordinates earlier in pipeline when scenery is being
* created, not when it is being loaded. Precalculate normals for each node
* as average of the normals of each containing polygon so Garoude shading is
* now supportable.
*
* Revision 1.3 1997/10/31 04:49:12 curt
* Tweaking vertex orders.
*
* Revision 1.2 1997/10/30 12:38:45 curt
* Working on new scenery subsystem.
*
* Revision 1.1 1997/10/28 21:14:54 curt
* Initial revision.
*
*/
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