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flightgear/Scenery/mesh.c

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/**************************************************************************
* mesh.c -- data structures and routines for processing terrain meshes
*
* Written by Curtis Olson, started May 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)
**************************************************************************/
#ifndef __CYGWIN32__
# include <malloc.h>
#endif
#ifdef WIN32
# include <windows.h>
#endif
#include <stdio.h>
#include <stdlib.h> /* atof(), atoi() */
#include <string.h>
#include <GL/glut.h>
#include "../constants.h"
#include "../types.h"
#include "../Math/fg_geodesy.h"
#include "../Math/fg_random.h"
#include "../Math/mat3.h"
#include "../Math/polar.h"
#include "mesh.h"
#include "common.h"
#include "scenery.h"
/* Temporary hack until we get the scenery management system running */
extern GLint mesh_hack;
extern struct MESH eg;
/* initialize the non-array mesh values */
void mesh_init(struct MESH *m) {
m->originx = 0.0;
m->originy = 0.0;
m->rows = 0;
m->cols = 0;
m->row_step = 0.0;
m->col_step = 0.0;
m->cur_row = 0;
m->cur_col = 0;
m->do_data = 0;
}
/* return a pointer to a new mesh structure (no data array allocated yet) */
struct MESH *(new_mesh)() {
struct MESH *mesh_ptr;
mesh_ptr = (struct MESH *)malloc(sizeof(struct MESH));
if ( mesh_ptr == 0 ) {
printf("Virtual memory exceeded\n");
exit(-1);
}
mesh_ptr->cur_row = 0;
mesh_ptr->cur_col = 0;
return(mesh_ptr);
}
/* return a pointer to a dynamically allocated array */
float *(new_mesh_data)(int nrows, int ncols) {
float *mesh_data_ptr;
mesh_data_ptr = (float *)malloc(nrows * ncols * sizeof(float));
if ( mesh_data_ptr == 0 ) {
printf("Virtual memory exceeded\n");
exit(-1);
}
printf("Allocated float(%d, %d)\n", nrows, ncols);
return(mesh_data_ptr);
}
/* set the option name in the mesh data structure */
void mesh_set_option_name(struct MESH *m, char *name) {
if ( strlen(name) < MAX_IDENT_LEN ) {
strcpy(m->option_name, name);
} else {
strncpy(m->option_name, name, MAX_IDENT_LEN - 1);
m->option_name[MAX_IDENT_LEN - 1] = '\0';
}
if ( strcmp(m->option_name, "do_data") == 0 ) {
m->do_data = 1;
} else {
m->do_data = 0;
}
}
/* set an option value in the mesh data structure */
void mesh_set_option_value(struct MESH *m, char *value) {
/* printf("Setting %s to %s\n", m->option_name, value); */
if ( m->do_data ) {
/* mesh data is a pseudo 2d array */
/* printf("Setting mesh_data[%d][%d] to %s\n", m->cur_row, m->cur_col,
value); */
m->mesh_data[m->cur_row * m->cols + m->cur_col] = atof(value);
m->cur_col++;
if ( m->cur_col >= m->cols ) {
m->cur_col = 0;
m->cur_row++;
if ( m->cur_row > m->rows ) {
m->do_data = 0;
}
}
} else if ( strcmp(m->option_name, "origin_lon") == 0 ) {
m->originx = atof(value);
} else if ( strcmp(m->option_name, "origin_lat") == 0 ) {
m->originy = atof(value);
} else if ( strcmp(m->option_name, "rows") == 0 ) {
m->rows = atoi(value);
} else if ( strcmp(m->option_name, "cols") == 0 ) {
m->cols = atoi(value);
} else if ( strcmp(m->option_name, "row_step") == 0 ) {
m->row_step = atof(value);
} else if ( strcmp(m->option_name, "col_step") == 0 ) {
m->col_step = atof(value);
} else {
printf("Unknown option %s with value %s, ignoring ...\n",
m->option_name, value);
}
}
/* do whatever needs to be done with the mesh now that it's been
loaded, such as generating the OpenGL call list. */
void mesh_do_it(struct MESH *m) {
mesh_hack = mesh_to_OpenGL(m);
}
/* return the current altitude based on mesh data. We should rewrite
* this to interpolate exact values, but for now this is good enough */
double mesh_altitude(double lon, double lat) {
/* we expect incoming (lon,lat) to be in arcsec for now */
double xlocal, ylocal, dx, dy, zA, zB, elev;
int x1, y1, z1, x2, y2, z2, x3, y3, z3;
int xindex, yindex;
int skip;
skip = scenery.terrain_skip;
/* determine if we are in the lower triangle or the upper triangle
______
| /|
| / |
| / |
|/ |
------
then calculate our end points
*/
xlocal = (lon - eg.originx) / eg.col_step;
ylocal = (lat - eg.originy) / eg.row_step;
xindex = (int)(xlocal / skip) * skip;
yindex = (int)(ylocal / skip) * skip;
if ( (xindex < 0) || (xindex + skip >= eg.cols) ||
(yindex < 0) || (yindex + skip >= eg.rows) ) {
return(-9999);
}
dx = xlocal - xindex;
dy = ylocal - yindex;
if ( dx > dy ) {
/* lower triangle */
/* printf(" Lower triangle\n"); */
x1 = xindex;
y1 = yindex;
z1 = eg.mesh_data[y1 * eg.cols + x1];
x2 = xindex + skip;
y2 = yindex;
z2 = eg.mesh_data[y2 * eg.cols + x2];
x3 = xindex + skip;
y3 = yindex + skip;
z3 = eg.mesh_data[y3 * eg.cols + x3];
/* printf(" dx = %.2f dy = %.2f\n", dx, dy);
printf(" (x1,y1,z1) = (%d,%d,%d)\n", x1, y1, z1);
printf(" (x2,y2,z2) = (%d,%d,%d)\n", x2, y2, z2);
printf(" (x3,y3,z3) = (%d,%d,%d)\n", x3, y3, z3); */
zA = dx * (z2 - z1) / skip + z1;
zB = dx * (z3 - z1) / skip + z1;
/* printf(" zA = %.2f zB = %.2f\n", zA, zB); */
if ( dx > EPSILON ) {
elev = dy * (zB - zA) / dx + zA;
} else {
elev = zA;
}
} else {
/* upper triangle */
/* printf(" Upper triangle\n"); */
x1 = xindex;
y1 = yindex;
z1 = eg.mesh_data[y1 * eg.cols + x1];
x2 = xindex;
y2 = yindex + skip;
z2 = eg.mesh_data[y2 * eg.cols + x2];
x3 = xindex + skip;
y3 = yindex + skip;
z3 = eg.mesh_data[y3 * eg.cols + x3];
/* printf(" dx = %.2f dy = %.2f\n", dx, dy);
printf(" (x1,y1,z1) = (%d,%d,%d)\n", x1, y1, z1);
printf(" (x2,y2,z2) = (%d,%d,%d)\n", x2, y2, z2);
printf(" (x3,y3,z3) = (%d,%d,%d)\n", x3, y3, z3); */
zA = dy * (z2 - z1) / skip + z1;
zB = dy * (z3 - z1) / skip + z1;
/* printf(" zA = %.2f zB = %.2f\n", zA, zB );
printf(" xB - xA = %.2f\n", eg.col_step * dy / eg.row_step); */
if ( dy > EPSILON ) {
elev = dx * (zB - zA) / dy + zA;
} else {
elev = zA;
}
}
return(elev);
}
/* walk through mesh and make opengl calls */
GLint mesh_to_OpenGL(struct MESH *m) {
GLint mesh;
/* static GLfloat color[4] = { 0.5, 0.4, 0.25, 1.0 }; */ /* dark desert */
static GLfloat color[4] = { 0.5, 0.5, 0.25, 1.0 };
double centerx, centery;
double randx, randy;
float x1, y1, x2, y2, z11, z12, z21, z22;
struct fgCartesianPoint p11, p12, p21, p22, c;
double gc_lon, gc_lat, sl_radius;
MAT3vec v1, v2, normal;
int i, j, istep, jstep, iend, jend;
float temp;
printf("In mesh2GL(), generating GL call list.\n");
/* Detail level. This is how big a step we take as we walk
* through the DEM data set. This value is initialized in
* .../Scenery/scenery.c:fgSceneryInit() */
istep = jstep = scenery.terrain_skip ;
centerx = m->originx + (m->rows * m->row_step) / 2.0;
centery = m->originy + (m->cols * m->col_step) / 2.0;
fgGeodToGeoc(centery*ARCSEC_TO_RAD, 0, &sl_radius, &gc_lat);
c = fgPolarToCart(centerx*ARCSEC_TO_RAD, gc_lat, sl_radius);
scenery.center = c;
mesh = glGenLists(1);
glNewList(mesh, GL_COMPILE);
/* glMaterialfv( GL_FRONT, GL_AMBIENT_AND_DIFFUSE, color ); */
glColor3fv(color);
iend = m->cols - 1;
jend = m->rows - 1;
y1 = m->originy;
y2 = y1 + (m->col_step * istep);
for ( i = 0; i < iend; i += istep ) {
x1 = m->originx;
x2 = x1 + (m->row_step * jstep);
glBegin(GL_TRIANGLE_STRIP);
for ( j = 0; j < jend; j += jstep ) {
z11 = m->mesh_data[i * m->cols + j ];
z12 = m->mesh_data[(i+istep) * m->cols + j ];
z21 = m->mesh_data[i * m->cols + (j+jstep)];
z22 = m->mesh_data[(i+istep) * m->cols + (j+jstep)];
/* printf("A geodetic point is (%.2f, %.2f, %.2f)\n",
x1, y1, z11); */
gc_lon = x1*ARCSEC_TO_RAD;
fgGeodToGeoc(y1*ARCSEC_TO_RAD, z11, &sl_radius, &gc_lat);
/* printf("A geocentric point is (%.2f, %.2f, %.2f)\n", gc_lon,
gc_lat, sl_radius+z11); */
p11 = fgPolarToCart(gc_lon, gc_lat, sl_radius+z11);
/* printf("A cart point is (%.8f, %.8f, %.8f)\n",
p11.x, p11.y, p11.z); */
gc_lon = x1*ARCSEC_TO_RAD;
fgGeodToGeoc(y2*ARCSEC_TO_RAD, z12, &sl_radius, &gc_lat);
p12 = fgPolarToCart(gc_lon, gc_lat, sl_radius+z12);
gc_lon = x2*ARCSEC_TO_RAD;
fgGeodToGeoc(y1*ARCSEC_TO_RAD, z21, &sl_radius, &gc_lat);
p21 = fgPolarToCart(gc_lon, gc_lat, sl_radius+z21);
gc_lon = x2*ARCSEC_TO_RAD;
fgGeodToGeoc(y2*ARCSEC_TO_RAD, z22, &sl_radius, &gc_lat);
p22 = fgPolarToCart(gc_lon, gc_lat, sl_radius+z22);
v1[0] = p22.y - p11.y; v1[1] = p22.z - p11.z; v1[2] = z22 - z11;
v2[0] = p12.y - p11.y; v2[1] = p12.z - p11.z; v2[2] = z12 - z11;
MAT3cross_product(normal, v1, v2);
MAT3_NORMALIZE_VEC(normal,temp);
glNormal3d(normal[0], normal[1], normal[2]);
/* printf("normal 1 = (%.2f %.2f %.2f\n", normal[0], normal[1],
normal[2]); */
if ( j == 0 ) {
/* first time through */
glVertex3d(p12.x - c.x, p12.y - c.y, p12.z - c.z);
glVertex3d(p11.x - c.x, p11.y - c.y, p11.z - c.z);
}
glVertex3d(p22.x - c.x, p22.y - c.y, p22.z - c.z);
v2[0] = p21.y - p11.y; v2[1] = p21.z - p11.z; v2[2] = z21 - z11;
MAT3cross_product(normal, v2, v1);
MAT3_NORMALIZE_VEC(normal,temp);
glNormal3d(normal[0], normal[1], normal[2]);
/* printf("normal 2 = (%.2f %.2f %.2f\n", normal[0], normal[1],
normal[2]); */
glVertex3d(p21.x - c.x, p21.y - c.y, p21.z - c.z);
x1 += m->row_step * jstep;
x2 += m->row_step * jstep;
}
glEnd();
y1 += m->col_step * istep;
y2 += m->col_step * istep;
}
/* this will go, it's only here for testing/debugging */
for ( i = 0; i < 200; i++ ) {
randx = fg_random() * 3600.0;
randy = fg_random() * 3600.0;
/* mesh_make_test_object(m->originx + randx, m->originy + randy); */
}
glEndList();
return(mesh);
}
/* $Log$
/* Revision 1.21 1997/08/27 03:30:27 curt
/* Changed naming scheme of basic shared structures.
/*
* Revision 1.20 1997/08/19 23:55:08 curt
* Worked on better simulating real lighting.
*
* Revision 1.19 1997/08/06 00:24:28 curt
* Working on correct real time sun lighting.
*
* Revision 1.18 1997/08/02 19:10:14 curt
* Incorporated mesh2GL.c into mesh.c
*
* Revision 1.17 1997/07/18 23:41:26 curt
* Tweaks for building with Cygnus Win32 compiler.
*
* Revision 1.16 1997/07/16 20:04:51 curt
* Minor tweaks to aid Win32 port.
*
* Revision 1.15 1997/07/14 16:26:04 curt
* Testing/playing -- placed objects randomly across the entire terrain.
*
* Revision 1.14 1997/07/12 04:01:14 curt
* Added #include <Windows32/Base.h> to help Win32 compiling.
*
* Revision 1.13 1997/07/12 02:27:11 curt
* Looking at potential scenery transformation/coordinate system problems.
*
* Revision 1.12 1997/07/11 03:23:19 curt
* Solved some scenery display/orientation problems. Still have a positioning
* (or transformation?) problem.
*
* Revision 1.11 1997/07/11 01:30:02 curt
* More tweaking of terrian floor.
*
* Revision 1.10 1997/07/10 04:26:38 curt
* We now can interpolated ground elevation for any position in the grid. We
* can use this to enforce a "hard" ground. We still need to enforce some
* bounds checking so that we don't try to lookup data points outside the
* grid data set.
*
* Revision 1.9 1997/07/10 02:22:10 curt
* Working on terrain elevation interpolation routine.
*
* Revision 1.8 1997/07/09 21:31:15 curt
* Working on making the ground "hard."
*
* Revision 1.7 1997/07/08 18:20:13 curt
* Working on establishing a hard ground.
*
* Revision 1.6 1997/06/29 21:16:49 curt
* More twiddling with the Scenery Management system.
*
* Revision 1.5 1997/06/22 21:44:41 curt
* Working on intergrating the VRML (subset) parser.
*
* Revision 1.4 1997/05/30 19:30:17 curt
* The LaRCsim flight model is starting to look like it is working.
*
* Revision 1.3 1997/05/23 15:40:41 curt
* Added GNU copyright headers.
*
* Revision 1.2 1997/05/19 18:20:50 curt
* Slight change to origin key words.
*
* Revision 1.1 1997/05/16 16:07:04 curt
* Initial revision.
*
*/
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