Pileus Git - grits/blob - src/grits-opengl.c

   1 /*
   2  * Copyright (C) 2009-2011 Andy Spencer <andy753421@gmail.com>
   3  *
   4  * This program is free software: you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation, either version 3 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  16  */
  17
  18 /**
  19  * SECTION:grits-opengl
  20  * @short_description: OpenGL based virtual globe
  21  *
  22  * #GritsOpenGL is the core rendering engine used by grits. Theoretically other
  23  * renderers could be writte, but they have not been. GritsOpenGL uses the ROAM
  24  * algorithm for updating surface mesh the planet. The only thing GritsOpenGL
  25  * can actually render on it's own is a wireframe of a sphere.
  26  *
  27  * GritsOpenGL requires (at least) OpenGL 2.0.
  28  */
  29
  30 #include <config.h>
  31 #include <math.h>
  32 #include <string.h>
  33 #include <gdk/gdkkeysyms.h>
  34 #include <gtk/gtk.h>
  35
  36 #include "grits-opengl.h"
  37 #include "grits-util.h"
  38 #include "gtkgl.h"
  39 #include "roam.h"
  40
  41 // #define ROAM_DEBUG
  42
  43 /* Tessellation, "finding intersecting triangles" */
  44 /* http://research.microsoft.com/pubs/70307/tr-2006-81.pdf */
  45 /* http://www.opengl.org/wiki/Alpha_Blending */
  46
  47 /* The unsorted/sroted GLists are blank head nodes,
  48  * This way us we can remove objects from the level just by fixing up links
  49  * I.e. we don't need to do a lookup to remove an object if we have its GList */
  50 struct RenderLevel {
  51         gint  num;
  52         GList unsorted;
  53         GList sorted;
  54 };
  55
  56 /***********
  57  * Helpers *
  58  ***********/
  59 static void _set_projection(GritsOpenGL *opengl)
  60 {
  61         double lat, lon, elev, rx, ry, rz;
  62         grits_viewer_get_location(GRITS_VIEWER(opengl), &lat, &lon, &elev);
  63         grits_viewer_get_rotation(GRITS_VIEWER(opengl), &rx, &ry, &rz);
  64
  65         /* Set projection and clipping planes */
  66         glMatrixMode(GL_PROJECTION);
  67         glLoadIdentity();
  68
  69         double width  = GTK_WIDGET(opengl)->allocation.width;
  70         double height = GTK_WIDGET(opengl)->allocation.height;
  71         double ang    = atan((height/2)/FOV_DIST)*2;
  72         double atmos  = 100000;
  73         double near   = MAX(elev*0.75 - atmos, 50); // View 100km of atmosphere
  74         double far    = elev + 2*EARTH_R + atmos;   // on both sides of the earth
  75
  76         glViewport(0, 0, width, height);
  77         gluPerspective(rad2deg(ang), width/height, near, far);
  78
  79         /* Setup camera and lighting */
  80         glMatrixMode(GL_MODELVIEW);
  81         glLoadIdentity();
  82
  83         /* Camera 1 */
  84         glRotatef(rx, 1, 0, 0);
  85         glRotatef(rz, 0, 0, 1);
  86
  87         /* Lighting */
  88         float light_position[] = {-13*EARTH_R, 1*EARTH_R, 3*EARTH_R, 1.0f};
  89         glLightfv(GL_LIGHT0, GL_POSITION, light_position);
  90
  91         /* Camera 2 */
  92         glTranslatef(0, 0, -elev2rad(elev));
  93         glRotatef(lat, 1, 0, 0);
  94         glRotatef(-lon, 0, 1, 0);
  95
  96         /* Update roam view */
  97         g_mutex_lock(&opengl->sphere_lock);
  98         roam_sphere_update_view(opengl->sphere);
  99         g_mutex_unlock(&opengl->sphere_lock);
 100 }
 101
 102 static void _set_settings(GritsOpenGL *opengl)
 103 {
 104         glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
 105         glEnable(GL_BLEND);
 106         glDisable(GL_ALPHA_TEST);
 107
 108         glEnable(GL_LIGHT0);
 109         glEnable(GL_LIGHTING);
 110
 111         glEnable(GL_LINE_SMOOTH);
 112
 113         glDisable(GL_TEXTURE_2D);
 114         glDisable(GL_COLOR_MATERIAL);
 115
 116         if (opengl->wireframe)
 117                 glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
 118         else
 119                 glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
 120
 121         /* Lighting */
 122 #ifdef ROAM_DEBUG
 123         float light_ambient[]  = {0.7f, 0.7f, 0.7f, 1.0f};
 124         float light_diffuse[]  = {2.0f, 2.0f, 2.0f, 1.0f};
 125 #else
 126         float light_ambient[]  = {0.2f, 0.2f, 0.2f, 1.0f};
 127         float light_diffuse[]  = {0.8f, 0.8f, 0.8f, 1.0f};
 128 #endif
 129         glLightfv(GL_LIGHT0, GL_AMBIENT,  light_ambient);
 130         glLightfv(GL_LIGHT0, GL_DIFFUSE,  light_diffuse);
 131
 132         /* Materials */
 133         float material_ambient[]  = {1.0, 1.0, 1.0, 1.0};
 134         float material_diffuse[]  = {1.0, 1.0, 1.0, 1.0};
 135         float material_specular[] = {0.0, 0.0, 0.0, 1.0};
 136         float material_emission[] = {0.0, 0.0, 0.0, 1.0};
 137         glMaterialfv(GL_FRONT_AND_BACK, GL_AMBIENT,  material_ambient);
 138         glMaterialfv(GL_FRONT_AND_BACK, GL_DIFFUSE,  material_diffuse);
 139         glMaterialfv(GL_FRONT_AND_BACK, GL_SPECULAR, material_specular);
 140         glMaterialfv(GL_FRONT_AND_BACK, GL_EMISSION, material_emission);
 141
 142 #ifdef ROAM_DEBUG
 143         glColor4f(1.0, 1.0, 1.0, 1.0);
 144         glLineWidth(2);
 145 #else
 146         glCullFace(GL_BACK);
 147         glEnable(GL_CULL_FACE);
 148
 149         glClearDepth(1.0);
 150         glDepthFunc(GL_LEQUAL);
 151         glEnable(GL_DEPTH_TEST);
 152 #endif
 153 }
 154
 155 static GPtrArray *_objects_to_array(GritsOpenGL *opengl, gboolean ortho)
 156 {
 157         GPtrArray *array = g_ptr_array_new();
 158         for (GList *i = opengl->objects->head; i; i = i->next) {
 159                 struct RenderLevel *level = i->data;
 160                 if ((ortho == TRUE  && level->num <  GRITS_LEVEL_HUD) ||
 161                     (ortho == FALSE && level->num >= GRITS_LEVEL_HUD))
 162                         continue;
 163                 for (GList *j = level->unsorted.next; j; j = j->next)
 164                         g_ptr_array_add(array, j->data);
 165                 for (GList *j = level->sorted.next;   j; j = j->next)
 166                         g_ptr_array_add(array, j->data);
 167         }
 168         return array;
 169 }
 170
 171 /*************
 172  * Callbacks *
 173  *************/
 174
 175 static gint run_picking(GritsOpenGL *opengl, GdkEvent *event,
 176                 GPtrArray *objects, GritsObject **top)
 177 {
 178         /* Setup picking buffers */
 179         guint buffer[100][4] = {};
 180         glSelectBuffer(G_N_ELEMENTS(buffer), (guint*)buffer);
 181         if (!opengl->pickmode)
 182                 glRenderMode(GL_SELECT);
 183         glInitNames();
 184
 185         /* Render/pick objects */
 186         for (guint i = 0; i < objects->len; i++) {
 187                 glPushName(i);
 188                 GritsObject *object = objects->pdata[i];
 189                 object->state.picked = FALSE;
 190                 grits_object_pick(object, opengl);
 191                 glPopName();
 192         }
 193
 194         int hits = glRenderMode(GL_RENDER);
 195
 196         /* Process hits */
 197         for (int i = 0; i < hits; i++) {
 198                 //g_debug("\tHit: %d",     i);
 199                 //g_debug("\t\tcount: %d", buffer[i][0]);
 200                 //g_debug("\t\tz1:    %f", (float)buffer[i][1]/0x7fffffff);
 201                 //g_debug("\t\tz2:    %f", (float)buffer[i][2]/0x7fffffff);
 202                 //g_debug("\t\tname:  %p", (gpointer)buffer[i][3]);
 203                 guint        index  = buffer[i][3];
 204                 GritsObject *object = objects->pdata[index];
 205                 object->state.picked = TRUE;
 206                 *top = object;
 207         }
 208
 209         /* Notify objects of pointer movements */
 210         for (guint i = 0; i < objects->len; i++) {
 211                 GritsObject *object = objects->pdata[i];
 212                 grits_object_set_pointer(object, event, object->state.picked);
 213         }
 214
 215         return hits;
 216 }
 217
 218 static gboolean run_mouse_move(GritsOpenGL *opengl, GdkEventMotion *event)
 219 {
 220         gdouble height = GTK_WIDGET(opengl)->allocation.height;
 221         gdouble gl_x   = event->x;
 222         gdouble gl_y   = height - event->y;
 223         gdouble delta  = opengl->pickmode ? 200 : 2;
 224
 225         if (opengl->pickmode) {
 226                 gtk_gl_begin(GTK_WIDGET(opengl));
 227                 glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 228         }
 229
 230         /* Save matricies */
 231         gdouble projection[16];
 232         gint    viewport[4]; // x=0,y=0,w,h
 233         glGetDoublev(GL_PROJECTION_MATRIX, projection);
 234         glGetIntegerv(GL_VIEWPORT, viewport);
 235         glMatrixMode(GL_MODELVIEW);  glPushMatrix();
 236         glMatrixMode(GL_PROJECTION); glPushMatrix();
 237
 238         g_mutex_lock(&opengl->objects_lock);
 239
 240         GritsObject *top = NULL;
 241         GPtrArray *ortho = _objects_to_array(opengl, TRUE);
 242         GPtrArray *world = _objects_to_array(opengl, FALSE);
 243
 244         /* Run perspective picking */
 245         glMatrixMode(GL_PROJECTION); glLoadIdentity();
 246         gluPickMatrix(gl_x, gl_y, delta, delta, viewport);
 247         glMultMatrixd(projection);
 248         gint world_hits = run_picking(opengl, (GdkEvent*)event, world, &top);
 249
 250         /* Run ortho picking */
 251         glMatrixMode(GL_PROJECTION); glLoadIdentity();
 252         gluPickMatrix(gl_x, gl_y, delta, delta, viewport);
 253         glMatrixMode(GL_MODELVIEW);  glLoadIdentity();
 254         glOrtho(0, viewport[2], viewport[3], 0, 1000, -1000);
 255         gint ortho_hits = run_picking(opengl, (GdkEvent*)event, ortho, &top);
 256
 257         /* Update cursor */
 258         static GdkCursor *cursor = NULL;
 259         static GdkWindow *window = NULL;
 260         if (!window || !cursor) {
 261                 cursor = gdk_cursor_new(GDK_FLEUR);
 262                 window = gtk_widget_get_window(GTK_WIDGET(opengl));
 263         }
 264         GdkCursor *topcursor = top && top->cursor ? top->cursor : cursor;
 265         gdk_window_set_cursor(window, topcursor);
 266
 267         g_debug("GritsOpenGL: run_mouse_move - hits=%d/%d,%d/%d ev=%.0lf,%.0lf",
 268                         world_hits, world->len, ortho_hits, ortho->len, gl_x, gl_y);
 269
 270         g_ptr_array_free(world, TRUE);
 271         g_ptr_array_free(ortho, TRUE);
 272
 273         g_mutex_unlock(&opengl->objects_lock);
 274
 275         /* Test unproject */
 276         //gdouble lat, lon, elev;
 277         //grits_viewer_unproject(GRITS_VIEWER(opengl),
 278         //              gl_x, gl_y, -1, &lat, &lon, &elev);
 279
 280         /* Cleanup */
 281         glMatrixMode(GL_PROJECTION); glPopMatrix();
 282         glMatrixMode(GL_MODELVIEW);  glPopMatrix();
 283
 284         if (opengl->pickmode)
 285                 gtk_gl_end(GTK_WIDGET(opengl));
 286
 287         return FALSE;
 288 }
 289
 290 static gboolean on_motion_notify(GritsOpenGL *opengl, GdkEventMotion *event, gpointer _)
 291 {
 292         opengl->mouse_queue = *event;
 293         gtk_widget_queue_draw(GTK_WIDGET(opengl));
 294         return FALSE;
 295 }
 296
 297 static void _draw_level(gpointer _level, gpointer _opengl)
 298 {
 299         GritsOpenGL *opengl = _opengl;
 300         struct RenderLevel *level = _level;
 301
 302         g_debug("GritsOpenGL: _draw_level - level=%-4d", level->num);
 303         int nsorted = 0, nunsorted = 0;
 304         GList *cur = NULL;
 305
 306         /* Configure individual levels */
 307         if (level->num < GRITS_LEVEL_WORLD) {
 308                 /* Disable depth for background levels */
 309                 glDepthMask(FALSE);
 310                 glDisable(GL_ALPHA_TEST);
 311         } else if (level->num < GRITS_LEVEL_OVERLAY) {
 312                 /* Enable depth and alpha for world levels */
 313                 glEnable(GL_ALPHA_TEST);
 314                 glAlphaFunc(GL_GREATER, 0.1);
 315         } else {
 316                 /* Disable depth for Overlay/HUD levels */
 317                 glDepthMask(FALSE);
 318         }
 319
 320         /* Start ortho */
 321         if (level->num >= GRITS_LEVEL_HUD) {
 322                 glMatrixMode(GL_PROJECTION); glPushMatrix(); glLoadIdentity();
 323                 glMatrixMode(GL_MODELVIEW);  glPushMatrix(); glLoadIdentity();
 324                 gint win_width  = GTK_WIDGET(opengl)->allocation.width;
 325                 gint win_height = GTK_WIDGET(opengl)->allocation.height;
 326                 glOrtho(0, win_width, win_height, 0, 1000, -1000);
 327         }
 328
 329         /* Draw unsorted objects without depth testing,
 330          * these are polygons, etc, rather than physical objects */
 331         glDisable(GL_DEPTH_TEST);
 332         for (cur = level->unsorted.next; cur; cur = cur->next, nunsorted++)
 333                 grits_object_draw(GRITS_OBJECT(cur->data), opengl);
 334
 335         /* Draw sorted objects using depth testing
 336          * These are things that are actually part of the world */
 337         glEnable(GL_DEPTH_TEST);
 338         for (cur = level->sorted.next; cur; cur = cur->next, nsorted++)
 339                 grits_object_draw(GRITS_OBJECT(cur->data), opengl);
 340
 341         /* End ortho */
 342         if (level->num >= GRITS_LEVEL_HUD) {
 343                 glMatrixMode(GL_PROJECTION); glPopMatrix();
 344                 glMatrixMode(GL_MODELVIEW);  glPopMatrix();
 345         }
 346
 347         /* Leave depth buffer write enabled */
 348         glDepthMask(TRUE);
 349
 350         /* TODO: Prune empty levels */
 351
 352         g_debug("GritsOpenGL: _draw_level - drew %d,%d objects",
 353                         nunsorted, nsorted);
 354 }
 355
 356 static gboolean on_expose(GritsOpenGL *opengl, GdkEventExpose *event, gpointer _)
 357 {
 358         g_debug("GritsOpenGL: on_expose - begin");
 359
 360         if (opengl->pickmode)
 361                 return run_mouse_move(opengl, (GdkEventMotion*)event);
 362
 363         if (opengl->mouse_queue.type != GDK_NOTHING) {
 364                 run_mouse_move(opengl, &opengl->mouse_queue);
 365                 opengl->mouse_queue.type = GDK_NOTHING;
 366         }
 367
 368         gtk_gl_begin(GTK_WIDGET(opengl));
 369
 370         _set_settings(opengl);
 371         glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 372
 373 #ifndef ROAM_DEBUG
 374         g_mutex_lock(&opengl->sphere_lock);
 375         roam_sphere_update_errors(opengl->sphere);
 376         roam_sphere_split_merge(opengl->sphere);
 377         g_mutex_unlock(&opengl->sphere_lock);
 378 #endif
 379
 380 #ifdef ROAM_DEBUG
 381         roam_sphere_draw(opengl->sphere);
 382         roam_sphere_draw_normals(opengl->sphere);
 383         (void)_draw_level;
 384 #else
 385         g_mutex_lock(&opengl->objects_lock);
 386         g_queue_foreach(opengl->objects, _draw_level, opengl);
 387         g_mutex_unlock(&opengl->objects_lock);
 388 #endif
 389
 390         gtk_gl_end(GTK_WIDGET(opengl));
 391
 392         g_debug("GritsOpenGL: on_expose - end\n");
 393         return FALSE;
 394 }
 395
 396 static gboolean on_key_press(GritsOpenGL *opengl, GdkEventKey *event, gpointer _)
 397 {
 398         g_debug("GritsOpenGL: on_key_press - key=%x, state=%x, plus=%x",
 399                         event->keyval, event->state, GDK_plus);
 400
 401         guint kv = event->keyval;
 402         /* Testing */
 403         if (kv == GDK_w) {
 404                 opengl->wireframe = !opengl->wireframe;
 405                 gtk_widget_queue_draw(GTK_WIDGET(opengl));
 406         }
 407         if (kv == GDK_p) {
 408                 opengl->pickmode = !opengl->pickmode;
 409                 gtk_widget_queue_draw(GTK_WIDGET(opengl));
 410         }
 411 #ifdef ROAM_DEBUG
 412         else if (kv == GDK_n) roam_sphere_split_one(opengl->sphere);
 413         else if (kv == GDK_p) roam_sphere_merge_one(opengl->sphere);
 414         else if (kv == GDK_r) roam_sphere_split_merge(opengl->sphere);
 415         else if (kv == GDK_u) roam_sphere_update_errors(opengl->sphere);
 416         gtk_widget_queue_draw(GTK_WIDGET(opengl));
 417 #endif
 418         return FALSE;
 419 }
 420
 421 static gboolean on_chained_event(GritsOpenGL *opengl, GdkEvent *event, gpointer _)
 422 {
 423         for (GList *i = opengl->objects->tail; i; i = i->prev) {
 424                 struct RenderLevel *level = i->data;
 425                 for (GList *j = level->unsorted.next; j; j = j->next)
 426                         if (grits_object_event(j->data, event))
 427                                 return TRUE;
 428                 for (GList *j = level->sorted.next;   j; j = j->next)
 429                         if (grits_object_event(j->data, event))
 430                                 return TRUE;
 431         }
 432         return FALSE;
 433 }
 434
 435 static void on_realize(GritsOpenGL *opengl, gpointer _)
 436 {
 437         g_debug("GritsOpenGL: on_realize");
 438         gtk_gl_begin(GTK_WIDGET(opengl));
 439
 440         /* Connect signals and idle functions now that opengl is fully initialized */
 441         gtk_widget_add_events(GTK_WIDGET(opengl), GDK_KEY_PRESS_MASK);
 442         g_signal_connect(opengl, "configure-event",  G_CALLBACK(_set_projection), NULL);
 443         g_signal_connect(opengl, "expose-event",     G_CALLBACK(on_expose),       NULL);
 444
 445         g_signal_connect(opengl, "key-press-event",  G_CALLBACK(on_key_press),    NULL);
 446
 447         g_signal_connect(opengl, "location-changed", G_CALLBACK(_set_projection), NULL);
 448         g_signal_connect(opengl, "rotation-changed", G_CALLBACK(_set_projection), NULL);
 449
 450         g_signal_connect(opengl, "motion-notify-event", G_CALLBACK(on_motion_notify), NULL);
 451         g_signal_connect_after(opengl, "key-press-event",      G_CALLBACK(on_chained_event), NULL);
 452         g_signal_connect_after(opengl, "key-release-event",    G_CALLBACK(on_chained_event), NULL);
 453         g_signal_connect_after(opengl, "button-press-event",   G_CALLBACK(on_chained_event), NULL);
 454         g_signal_connect_after(opengl, "button-release-event", G_CALLBACK(on_chained_event), NULL);
 455         g_signal_connect_after(opengl, "motion-notify-event",  G_CALLBACK(on_chained_event), NULL);
 456
 457         /* Re-queue resize incase configure was triggered before realize */
 458         gtk_widget_queue_resize(GTK_WIDGET(opengl));
 459 }
 460
 461 /*********************
 462  * GritsViewer methods *
 463  *********************/
 464 /**
 465  * grits_opengl_new:
 466  * @plugins: the plugins store to use
 467  * @prefs:   the preferences object to use
 468  *
 469  * Create a new OpenGL renderer.
 470  *
 471  * Returns: the new #GritsOpenGL
 472  */
 473 GritsViewer *grits_opengl_new(GritsPlugins *plugins, GritsPrefs *prefs)
 474 {
 475         g_debug("GritsOpenGL: new");
 476         GritsViewer *opengl = g_object_new(GRITS_TYPE_OPENGL, NULL);
 477         grits_viewer_setup(opengl, plugins, prefs);
 478         return opengl;
 479 }
 480
 481 static void grits_opengl_center_position(GritsViewer *_opengl, gdouble lat, gdouble lon, gdouble elev)
 482 {
 483         glRotatef(lon, 0, 1, 0);
 484         glRotatef(-lat, 1, 0, 0);
 485         glTranslatef(0, 0, elev2rad(elev));
 486 }
 487
 488 static void grits_opengl_project(GritsViewer *_opengl,
 489                 gdouble lat, gdouble lon, gdouble elev,
 490                 gdouble *px, gdouble *py, gdouble *pz)
 491 {
 492         GritsOpenGL *opengl = GRITS_OPENGL(_opengl);
 493         gdouble x, y, z;
 494         lle2xyz(lat, lon, elev, &x, &y, &z);
 495         gluProject(x, y, z,
 496                 opengl->sphere->view->model,
 497                 opengl->sphere->view->proj,
 498                 opengl->sphere->view->view,
 499                 px, py, pz);
 500 }
 501
 502 static void grits_opengl_unproject(GritsViewer *_opengl,
 503                 gdouble px, gdouble py, gdouble pz,
 504                 gdouble *lat, gdouble *lon, gdouble *elev)
 505 {
 506         GritsOpenGL *opengl = GRITS_OPENGL(_opengl);
 507         if (!opengl->sphere->view)
 508                 return;
 509         gdouble x, y, z;
 510         if (pz < 0) {
 511                 gfloat tmp = 0;
 512                 glReadPixels(px, py, 1, 1, GL_DEPTH_COMPONENT, GL_FLOAT, &tmp);
 513                 pz = tmp;
 514         }
 515         gluUnProject(px, py, pz,
 516                 opengl->sphere->view->model,
 517                 opengl->sphere->view->proj,
 518                 opengl->sphere->view->view,
 519                 &x, &y, &z);
 520         xyz2lle(x, y, z, lat, lon, elev);
 521         //g_message("GritsOpenGL: unproject - "
 522         //              "%4.0lf,%4.0lf,(%5.3lf) -> "
 523         //              "%8.0lf,%8.0lf,%8.0lf -> "
 524         //              "%6.2lf,%7.2lf,%4.0lf",
 525         //      px, py, pz, x, y, z, *lat, *lon, *elev);
 526 }
 527
 528 static void grits_opengl_set_height_func(GritsViewer *_opengl, GritsBounds *bounds,
 529                 RoamHeightFunc height_func, gpointer user_data, gboolean update)
 530 {
 531         GritsOpenGL *opengl = GRITS_OPENGL(_opengl);
 532         /* TODO: get points? */
 533         g_mutex_lock(&opengl->sphere_lock);
 534         GList *triangles = roam_sphere_get_intersect(opengl->sphere, TRUE,
 535                         bounds->n, bounds->s, bounds->e, bounds->w);
 536         for (GList *cur = triangles; cur; cur = cur->next) {
 537                 RoamTriangle *tri = cur->data;
 538                 RoamPoint *points[] = {tri->p.l, tri->p.m, tri->p.r, tri->split};
 539                 for (int i = 0; i < G_N_ELEMENTS(points); i++) {
 540                         if (bounds->n >= points[i]->lat && points[i]->lat >= bounds->s &&
 541                             bounds->e >= points[i]->lon && points[i]->lon >= bounds->w) {
 542                                 points[i]->height_func = height_func;
 543                                 points[i]->height_data = user_data;
 544                                 roam_point_update_height(points[i]);
 545                         }
 546                 }
 547         }
 548         g_list_free(triangles);
 549         g_mutex_unlock(&opengl->sphere_lock);
 550 }
 551
 552 static void _grits_opengl_clear_height_func_rec(RoamTriangle *root)
 553 {
 554         if (!root)
 555                 return;
 556         RoamPoint *points[] = {root->p.l, root->p.m, root->p.r, root->split};
 557         for (int i = 0; i < G_N_ELEMENTS(points); i++) {
 558                 points[i]->height_func = NULL;
 559                 points[i]->height_data = NULL;
 560                 roam_point_update_height(points[i]);
 561         }
 562         _grits_opengl_clear_height_func_rec(root->kids[0]);
 563         _grits_opengl_clear_height_func_rec(root->kids[1]);
 564 }
 565
 566 static void grits_opengl_clear_height_func(GritsViewer *_opengl)
 567 {
 568         GritsOpenGL *opengl = GRITS_OPENGL(_opengl);
 569         for (int i = 0; i < G_N_ELEMENTS(opengl->sphere->roots); i++)
 570                 _grits_opengl_clear_height_func_rec(opengl->sphere->roots[i]);
 571 }
 572
 573 static gint _objects_find(gconstpointer a, gconstpointer b)
 574 {
 575         const struct RenderLevel *level = a;
 576         const gint *key = b;
 577         return level->num == *key ? 0 : 1;
 578 }
 579
 580 static gint _objects_sort(gconstpointer _a, gconstpointer _b, gpointer _)
 581 {
 582         const struct RenderLevel *a = _a;
 583         const struct RenderLevel *b = _b;
 584         return a->num < b->num ? -1 :
 585                a->num > b->num ?  1 : 0;
 586 }
 587
 588 static void _objects_free(gpointer value, gpointer _)
 589 {
 590         struct RenderLevel *level = value;
 591         if (level->sorted.next)
 592                 g_list_free_full(level->sorted.next, g_object_unref);
 593         if (level->unsorted.next)
 594                 g_list_free_full(level->unsorted.next, g_object_unref);
 595         g_free(level);
 596 }
 597
 598 static void grits_opengl_add(GritsViewer *_opengl, GritsObject *object,
 599                 gint num, gboolean sort)
 600 {
 601         g_assert(GRITS_IS_OPENGL(_opengl));
 602         GritsOpenGL *opengl = GRITS_OPENGL(_opengl);
 603         g_mutex_lock(&opengl->objects_lock);
 604         struct RenderLevel *level = NULL;
 605         GList *tmp = g_queue_find_custom(opengl->objects, &num, _objects_find);
 606         if (tmp) {
 607                 level = tmp->data;
 608         } else {
 609                 level = g_new0(struct RenderLevel, 1);
 610                 level->num = num;
 611                 g_queue_insert_sorted(opengl->objects, level, _objects_sort, NULL);
 612         }
 613         GList *list = sort ? &level->sorted : &level->unsorted;
 614         /* Put the link in the list */
 615         GList *link = g_new0(GList, 1);
 616         link->data = object;
 617         link->prev = list;
 618         link->next = list->next;
 619         if (list->next)
 620                 list->next->prev = link;
 621         list->next = link;
 622         object->ref = link;
 623         g_object_ref(object);
 624         g_mutex_unlock(&opengl->objects_lock);
 625 }
 626
 627 void grits_opengl_remove(GritsViewer *_opengl, GritsObject *object)
 628 {
 629         g_assert(GRITS_IS_OPENGL(_opengl));
 630         GritsOpenGL *opengl = GRITS_OPENGL(_opengl);
 631         if (!object->ref)
 632                 return;
 633         g_mutex_lock(&opengl->objects_lock);
 634         GList *link = object->ref;
 635         /* Just unlink and free it, link->prev is assured */
 636         link->prev->next = link->next;
 637         if (link->next)
 638                 link->next->prev = link->prev;
 639         g_free(link);
 640         object->ref = NULL;
 641         g_object_unref(object);
 642         g_mutex_unlock(&opengl->objects_lock);
 643 }
 644
 645 /****************
 646  * GObject code *
 647  ****************/
 648 G_DEFINE_TYPE(GritsOpenGL, grits_opengl, GRITS_TYPE_VIEWER);
 649 static void grits_opengl_init(GritsOpenGL *opengl)
 650 {
 651         g_debug("GritsOpenGL: init");
 652         opengl->objects = g_queue_new();
 653         opengl->sphere  = roam_sphere_new(opengl);
 654         g_mutex_init(&opengl->objects_lock);
 655         g_mutex_init(&opengl->sphere_lock);
 656         gtk_gl_enable(GTK_WIDGET(opengl));
 657         gtk_widget_add_events(GTK_WIDGET(opengl), GDK_KEY_PRESS_MASK);
 658         g_signal_connect(opengl, "map", G_CALLBACK(on_realize), NULL);
 659 }
 660 static void grits_opengl_dispose(GObject *_opengl)
 661 {
 662         g_debug("GritsOpenGL: dispose");
 663         GritsOpenGL *opengl = GRITS_OPENGL(_opengl);
 664         if (opengl->objects) {
 665                 GQueue *objects = opengl->objects;;
 666                 opengl->objects = NULL;
 667                 g_mutex_lock(&opengl->objects_lock);
 668                 g_queue_foreach(objects, _objects_free, NULL);
 669                 g_queue_free(objects);
 670                 g_mutex_unlock(&opengl->objects_lock);
 671         }
 672         G_OBJECT_CLASS(grits_opengl_parent_class)->dispose(_opengl);
 673 }
 674 static void grits_opengl_finalize(GObject *_opengl)
 675 {
 676         g_debug("GritsOpenGL: finalize");
 677         GritsOpenGL *opengl = GRITS_OPENGL(_opengl);
 678         roam_sphere_free(opengl->sphere);
 679         g_mutex_clear(&opengl->objects_lock);
 680         g_mutex_clear(&opengl->sphere_lock);
 681         gtk_gl_disable(GTK_WIDGET(opengl));
 682         G_OBJECT_CLASS(grits_opengl_parent_class)->finalize(_opengl);
 683 }
 684 static void grits_opengl_class_init(GritsOpenGLClass *klass)
 685 {
 686         g_debug("GritsOpenGL: class_init");
 687         GObjectClass *gobject_class = G_OBJECT_CLASS(klass);
 688         gobject_class->finalize = grits_opengl_finalize;
 689         gobject_class->dispose = grits_opengl_dispose;
 690
 691         GritsViewerClass *viewer_class = GRITS_VIEWER_CLASS(klass);
 692         viewer_class->center_position   = grits_opengl_center_position;
 693         viewer_class->project           = grits_opengl_project;
 694         viewer_class->unproject         = grits_opengl_unproject;
 695         viewer_class->clear_height_func = grits_opengl_clear_height_func;
 696         viewer_class->set_height_func   = grits_opengl_set_height_func;
 697         viewer_class->add               = grits_opengl_add;
 698         viewer_class->remove            = grits_opengl_remove;
 699 }