1 /**************************************************************************
2 * mesh.c -- data structures and routines for processing terrain meshes
4 * Written by Curtis Olson, started May 1997.
6 * Copyright (C) 1997 Curtis L. Olson - curt@infoplane.com
8 * This program is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU General Public License as
10 * published by the Free Software Foundation; either version 2 of the
11 * License, or (at your option) any later version.
13 * This program is distributed in the hope that it will be useful, but
14 * WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * General Public License for more details.
18 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, write to the Free Software
20 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
23 * (Log is kept at end of this file)
24 **************************************************************************/
36 #include <stdlib.h> /* atof(), atoi() */
41 #include "../constants.h"
47 /* Temporary hack until we get the scenery management system running */
48 extern GLint mesh_hack;
49 extern struct mesh eg;
51 /* initialize the non-array mesh values */
52 void mesh_init(struct mesh *m) {
68 /* return a pointer to a new mesh structure (no data array allocated yet) */
69 struct mesh *(new_mesh)() {
70 struct mesh *mesh_ptr;
72 mesh_ptr = (struct mesh *)malloc(sizeof(struct mesh));
74 if ( mesh_ptr == 0 ) {
75 printf("Virtual memory exceeded\n");
79 mesh_ptr->cur_row = 0;
80 mesh_ptr->cur_col = 0;
86 /* return a pointer to a dynamically allocated array */
87 float *(new_mesh_data)(int nrows, int ncols) {
90 mesh_data_ptr = (float *)malloc(nrows * ncols * sizeof(float));
92 if ( mesh_data_ptr == 0 ) {
93 printf("Virtual memory exceeded\n");
97 printf("Allocated float(%d, %d)\n", nrows, ncols);
99 return(mesh_data_ptr);
103 /* set the option name in the mesh data structure */
104 void mesh_set_option_name(struct mesh *m, char *name) {
105 if ( strlen(name) < MAX_IDENT_LEN ) {
106 strcpy(m->option_name, name);
108 strncpy(m->option_name, name, MAX_IDENT_LEN - 1);
109 m->option_name[MAX_IDENT_LEN - 1] = '\0';
111 if ( strcmp(m->option_name, "do_data") == 0 ) {
119 /* set an option value in the mesh data structure */
120 void mesh_set_option_value(struct mesh *m, char *value) {
121 /* printf("Setting %s to %s\n", m->option_name, value); */
124 /* mesh data is a pseudo 2d array */
125 /* printf("Setting mesh_data[%d][%d] to %s\n", m->cur_row, m->cur_col,
127 m->mesh_data[m->cur_row * m->cols + m->cur_col] = atof(value);
129 if ( m->cur_col >= m->cols ) {
132 if ( m->cur_row > m->rows ) {
136 } else if ( strcmp(m->option_name, "origin_lon") == 0 ) {
137 m->originx = atof(value);
138 } else if ( strcmp(m->option_name, "origin_lat") == 0 ) {
139 m->originy = atof(value);
140 } else if ( strcmp(m->option_name, "rows") == 0 ) {
141 m->rows = atoi(value);
142 } else if ( strcmp(m->option_name, "cols") == 0 ) {
143 m->cols = atoi(value);
144 } else if ( strcmp(m->option_name, "row_step") == 0 ) {
145 m->row_step = atof(value);
146 } else if ( strcmp(m->option_name, "col_step") == 0 ) {
147 m->col_step = atof(value);
149 printf("Unknown option %s with value %s, ignoring ...\n",
150 m->option_name, value);
155 /* do whatever needs to be done with the mesh now that it's been
156 loaded, such as generating the OpenGL call list. */
157 void mesh_do_it(struct mesh *m) {
158 mesh_hack = mesh2GL(m);
162 /* return the current altitude based on mesh data. We should rewrite
163 * this to interpolate exact values, but for now this is good enough */
164 double mesh_altitude(double lon, double lat) {
165 /* we expect incoming (lon,lat) to be in arcsec for now */
167 double xlocal, ylocal, dx, dy, zA, zB, elev;
168 int x1, y1, z1, x2, y2, z2, x3, y3, z3;
172 skip = cur_scenery_params.terrain_skip;
173 /* determine if we are in the lower triangle or the upper triangle
181 then calculate our end points
184 xlocal = (lon - eg.originx) / eg.col_step;
185 ylocal = (lat - eg.originy) / eg.row_step;
187 xindex = (int)(xlocal / skip) * skip;
188 yindex = (int)(ylocal / skip) * skip;
190 if ( (xindex < 0) || (xindex + skip >= eg.cols) ||
191 (yindex < 0) || (yindex + skip >= eg.rows) ) {
195 dx = xlocal - xindex;
196 dy = ylocal - yindex;
200 printf(" Lower triangle\n");
204 z1 = eg.mesh_data[y1 * eg.cols + x1];
208 z2 = eg.mesh_data[y2 * eg.cols + x2];
212 z3 = eg.mesh_data[y3 * eg.cols + x3];
214 printf(" dx = %.2f dy = %.2f\n", dx, dy);
215 printf(" (x1,y1,z1) = (%d,%d,%d)\n", x1, y1, z1);
216 printf(" (x2,y2,z2) = (%d,%d,%d)\n", x2, y2, z2);
217 printf(" (x3,y3,z3) = (%d,%d,%d)\n", x3, y3, z3);
219 zA = dx * (z2 - z1) / skip + z1;
220 zB = dx * (z3 - z1) / skip + z1;
222 printf(" zA = %.2f zB = %.2f\n", zA, zB);
224 if ( dx > EPSILON ) {
225 elev = dy * (zB - zA) / dx + zA;
231 printf(" Upper triangle\n");
235 z1 = eg.mesh_data[y1 * eg.cols + x1];
239 z2 = eg.mesh_data[y2 * eg.cols + x2];
243 z3 = eg.mesh_data[y3 * eg.cols + x3];
245 printf(" dx = %.2f dy = %.2f\n", dx, dy);
246 printf(" (x1,y1,z1) = (%d,%d,%d)\n", x1, y1, z1);
247 printf(" (x2,y2,z2) = (%d,%d,%d)\n", x2, y2, z2);
248 printf(" (x3,y3,z3) = (%d,%d,%d)\n", x3, y3, z3);
250 zA = dy * (z2 - z1) / skip + z1;
251 zB = dy * (z3 - z1) / skip + z1;
253 printf(" zA = %.2f zB = %.2f\n", zA, zB );
254 printf(" xB - xA = %.2f\n", eg.col_step * dy / eg.row_step);
256 if ( dy > EPSILON ) {
257 elev = dx * (zB - zA) / dy + zA;
268 /* Revision 1.16 1997/07/16 20:04:51 curt
269 /* Minor tweaks to aid Win32 port.
271 * Revision 1.15 1997/07/14 16:26:04 curt
272 * Testing/playing -- placed objects randomly across the entire terrain.
274 * Revision 1.14 1997/07/12 04:01:14 curt
275 * Added #include <Windows32/Base.h> to help Win32 compiling.
277 * Revision 1.13 1997/07/12 02:27:11 curt
278 * Looking at potential scenery transformation/coordinate system problems.
280 * Revision 1.12 1997/07/11 03:23:19 curt
281 * Solved some scenery display/orientation problems. Still have a positioning
282 * (or transformation?) problem.
284 * Revision 1.11 1997/07/11 01:30:02 curt
285 * More tweaking of terrian floor.
287 * Revision 1.10 1997/07/10 04:26:38 curt
288 * We now can interpolated ground elevation for any position in the grid. We
289 * can use this to enforce a "hard" ground. We still need to enforce some
290 * bounds checking so that we don't try to lookup data points outside the
293 * Revision 1.9 1997/07/10 02:22:10 curt
294 * Working on terrain elevation interpolation routine.
296 * Revision 1.8 1997/07/09 21:31:15 curt
297 * Working on making the ground "hard."
299 * Revision 1.7 1997/07/08 18:20:13 curt
300 * Working on establishing a hard ground.
302 * Revision 1.6 1997/06/29 21:16:49 curt
303 * More twiddling with the Scenery Management system.
305 * Revision 1.5 1997/06/22 21:44:41 curt
306 * Working on intergrating the VRML (subset) parser.
308 * Revision 1.4 1997/05/30 19:30:17 curt
309 * The LaRCsim flight model is starting to look like it is working.
311 * Revision 1.3 1997/05/23 15:40:41 curt
312 * Added GNU copyright headers.
314 * Revision 1.2 1997/05/19 18:20:50 curt
315 * Slight change to origin key words.
317 * Revision 1.1 1997/05/16 16:07:04 curt