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         GList unsorted;
  52         GList sorted;
  53 };
  54
  55 /***********
  56  * Helpers *
  57  ***********/
  58 static void _set_visuals(GritsOpenGL *opengl)
  59 {
  60         double lat, lon, elev, rx, ry, rz;
  61         grits_viewer_get_location(GRITS_VIEWER(opengl), &lat, &lon, &elev);
  62         grits_viewer_get_rotation(GRITS_VIEWER(opengl), &rx, &ry, &rz);
  63
  64         /* Set projection and clipping planes */
  65         glMatrixMode(GL_PROJECTION);
  66         glLoadIdentity();
  67
  68         double width  = GTK_WIDGET(opengl)->allocation.width;
  69         double height = GTK_WIDGET(opengl)->allocation.height;
  70         double ang    = atan(height/FOV_DIST);
  71         double atmos  = 100000;
  72         double near   = MAX(elev*0.75 - atmos, 50); // View 100km of atmosphere
  73         double far    = elev + 2*EARTH_R + atmos;   // on both sides of the earth
  74
  75         grits_viewer_get_location(GRITS_VIEWER(opengl), &lat, &lon, &elev);
  76         glViewport(0, 0, width, height);
  77         gluPerspective(rad2deg(ang)*2, 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 #ifdef ROAM_DEBUG
  89         float light_ambient[]  = {0.7f, 0.7f, 0.7f, 1.0f};
  90         float light_diffuse[]  = {2.0f, 2.0f, 2.0f, 1.0f};
  91 #else
  92         float light_ambient[]  = {0.2f, 0.2f, 0.2f, 1.0f};
  93         float light_diffuse[]  = {0.8f, 0.8f, 0.8f, 1.0f};
  94 #endif
  95         float light_position[] = {-13*EARTH_R, 1*EARTH_R, 3*EARTH_R, 1.0f};
  96         glLightfv(GL_LIGHT0, GL_AMBIENT,  light_ambient);
  97         glLightfv(GL_LIGHT0, GL_DIFFUSE,  light_diffuse);
  98         glLightfv(GL_LIGHT0, GL_POSITION, light_position);
  99         glEnable(GL_LIGHT0);
 100         glEnable(GL_LIGHTING);
 101
 102         float material_ambient[]  = {1.0, 1.0, 1.0, 1.0};
 103         float material_diffuse[]  = {1.0, 1.0, 1.0, 1.0};
 104         float material_specular[] = {0.0, 0.0, 0.0, 1.0};
 105         float material_emission[] = {0.0, 0.0, 0.0, 1.0};
 106         glMaterialfv(GL_FRONT_AND_BACK, GL_AMBIENT,  material_ambient);
 107         glMaterialfv(GL_FRONT_AND_BACK, GL_DIFFUSE,  material_diffuse);
 108         glMaterialfv(GL_FRONT_AND_BACK, GL_SPECULAR, material_specular);
 109         glMaterialfv(GL_FRONT_AND_BACK, GL_EMISSION, material_emission);
 110         glDisable(GL_TEXTURE_2D);
 111         glDisable(GL_COLOR_MATERIAL);
 112
 113         /* Camera 2 */
 114         glTranslatef(0, 0, -elev2rad(elev));
 115         glRotatef(lat, 1, 0, 0);
 116         glRotatef(-lon, 0, 1, 0);
 117
 118         glDisable(GL_ALPHA_TEST);
 119
 120         glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
 121         glEnable(GL_BLEND);
 122
 123 #ifndef ROAM_DEBUG
 124         glCullFace(GL_BACK);
 125         glEnable(GL_CULL_FACE);
 126
 127         glClearDepth(1.0);
 128         glDepthFunc(GL_LEQUAL);
 129         glEnable(GL_DEPTH_TEST);
 130 #endif
 131
 132         glEnable(GL_LINE_SMOOTH);
 133
 134         glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
 135         //glShadeModel(GL_FLAT);
 136
 137         g_mutex_lock(opengl->sphere_lock);
 138         roam_sphere_update_view(opengl->sphere);
 139         g_mutex_unlock(opengl->sphere_lock);
 140 }
 141
 142 static gboolean _foreach_object_cb(gpointer key, gpointer value, gpointer pointers)
 143 {
 144         struct RenderLevel *level = value;
 145         GFunc    user_func = ((gpointer*)pointers)[0];
 146         gpointer user_data = ((gpointer*)pointers)[1];
 147         for (GList *cur = level->unsorted.next; cur; cur = cur->next)
 148                 user_func(cur->data, user_data);
 149         for (GList *cur = level->sorted.next;   cur; cur = cur->next)
 150                 user_func(cur->data, user_data);
 151         return FALSE;
 152 }
 153
 154 static void _foreach_object(GritsOpenGL *opengl, GFunc func, gpointer user_data)
 155 {
 156         gpointer pointers[2] = {func, user_data};
 157         g_tree_foreach(opengl->objects, _foreach_object_cb, pointers);
 158 }
 159
 160 static void _add_object(GritsObject *object, GPtrArray *array)
 161 {
 162         g_ptr_array_add(array, object);
 163 }
 164
 165 static GPtrArray *_objects_to_array(GritsOpenGL *opengl)
 166 {
 167         GPtrArray *array = g_ptr_array_new();
 168         _foreach_object(opengl, (GFunc)_add_object, array);
 169         return array;
 170 }
 171
 172 /*************
 173  * Callbacks *
 174  *************/
 175 static gboolean on_configure(GritsOpenGL *opengl, GdkEventConfigure *event, gpointer _)
 176 {
 177         g_debug("GritsOpenGL: on_configure");
 178
 179         _set_visuals(opengl);
 180 #ifndef ROAM_DEBUG
 181         g_mutex_lock(opengl->sphere_lock);
 182         roam_sphere_update_errors(opengl->sphere);
 183         g_mutex_unlock(opengl->sphere_lock);
 184 #endif
 185
 186         return FALSE;
 187 }
 188
 189 static gboolean _draw_level(gpointer key, gpointer value, gpointer user_data)
 190 {
 191         g_debug("GritsOpenGL: _draw_level - level=%-4ld", (glong)key);
 192         GritsOpenGL *opengl = user_data;
 193         struct RenderLevel *level = value;
 194         int nsorted = 0, nunsorted = 0;
 195         GList *cur = NULL;
 196
 197         /* Draw opaque objects without sorting */
 198         glDepthMask(TRUE);
 199         glClear(GL_DEPTH_BUFFER_BIT);
 200         for (cur = level->unsorted.next; cur; cur = cur->next, nunsorted++)
 201                 grits_object_draw(GRITS_OBJECT(cur->data), opengl);
 202
 203         /* Freeze depth buffer and draw transparent objects sorted */
 204         /* TODO: sorting */
 205         //glDepthMask(FALSE);
 206         glAlphaFunc(GL_GREATER, 0.1);
 207         for (cur = level->sorted.next; cur; cur = cur->next, nsorted++)
 208                 grits_object_draw(GRITS_OBJECT(cur->data), opengl);
 209
 210         /* TODO: Prune empty levels */
 211
 212         g_debug("GritsOpenGL: _draw_level - drew %d,%d objects",
 213                         nunsorted, nsorted);
 214         return FALSE;
 215 }
 216
 217 static gboolean on_expose(GritsOpenGL *opengl, GdkEventExpose *event, gpointer _)
 218 {
 219         g_debug("GritsOpenGL: on_expose - begin");
 220
 221         gtk_gl_begin(GTK_WIDGET(opengl));
 222
 223         glClear(GL_COLOR_BUFFER_BIT);
 224
 225         _set_visuals(opengl);
 226 #ifdef ROAM_DEBUG
 227         glColor4f(1.0, 1.0, 1.0, 1.0);
 228         glLineWidth(2);
 229         glDisable(GL_TEXTURE_2D);
 230         glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
 231         roam_sphere_draw(opengl->sphere);
 232         (void)_draw_level;
 233         //roam_sphere_draw_normals(opengl->sphere);
 234 #else
 235         g_mutex_lock(opengl->objects_lock);
 236         g_tree_foreach(opengl->objects, _draw_level, opengl);
 237         if (opengl->wireframe) {
 238                 glClear(GL_DEPTH_BUFFER_BIT);
 239                 glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
 240                 roam_sphere_draw(opengl->sphere);
 241                 g_tree_foreach(opengl->objects, _draw_level, opengl);
 242         }
 243         g_mutex_unlock(opengl->objects_lock);
 244 #endif
 245
 246         gtk_gl_end(GTK_WIDGET(opengl));
 247
 248         g_debug("GritsOpenGL: on_expose - end\n");
 249         return FALSE;
 250 }
 251
 252 static gboolean on_motion_notify(GritsOpenGL *opengl, GdkEventMotion *event, gpointer _)
 253 {
 254         gdouble height = GTK_WIDGET(opengl)->allocation.height;
 255         gdouble gl_x   = event->x;
 256         gdouble gl_y   = height - event->y;
 257
 258         /* Configure view */
 259         gint viewport[4];
 260         gdouble projection[16];
 261         glGetIntegerv(GL_VIEWPORT, viewport);
 262         glGetDoublev(GL_PROJECTION_MATRIX, projection);
 263
 264         glMatrixMode(GL_PROJECTION);
 265         glPushMatrix();
 266         glLoadIdentity();
 267         gluPickMatrix(gl_x, gl_y, 2, 2, viewport);
 268         glMultMatrixd(projection);
 269
 270         /* Prepare for picking */
 271         guint buffer[100][4] = {};
 272         glSelectBuffer(G_N_ELEMENTS(buffer), (guint*)buffer);
 273         glRenderMode(GL_SELECT);
 274         glInitNames();
 275
 276         /* Run picking */
 277         g_mutex_lock(opengl->objects_lock);
 278         GPtrArray *objects = _objects_to_array(opengl);
 279         for (guint i = 0; i < objects->len; i++) {
 280                 glPushName(i);
 281                 GritsObject *object = objects->pdata[i];
 282                 object->state.picked = FALSE;
 283                 grits_object_pick(object, opengl);
 284                 glPopName();
 285         }
 286         int hits = glRenderMode(GL_RENDER);
 287         g_debug("GritsOpenGL: on_motion_notify - hits=%d ev=%.0lf,%.0lf",
 288                         hits, gl_x, gl_y);
 289         for (int i = 0; i < hits; i++) {
 290                 //g_debug("\tHit: %d",     i);
 291                 //g_debug("\t\tcount: %d", buffer[i][0]);
 292                 //g_debug("\t\tz1:    %f", (float)buffer[i][1]/0x7fffffff);
 293                 //g_debug("\t\tz2:    %f", (float)buffer[i][2]/0x7fffffff);
 294                 //g_debug("\t\tname:  %p", (gpointer)buffer[i][3]);
 295                 guint        index  = buffer[i][3];
 296                 GritsObject *object = objects->pdata[index];
 297                 object->state.picked = TRUE;
 298         }
 299         for (guint i = 0; i < objects->len; i++) {
 300                 GritsObject *object = objects->pdata[i];
 301                 grits_object_set_pointer(object, object->state.picked);
 302         }
 303         g_ptr_array_free(objects, TRUE);
 304         g_mutex_unlock(opengl->objects_lock);
 305
 306         /* Cleanup */
 307         glMatrixMode(GL_PROJECTION);
 308         glPopMatrix();
 309
 310         return FALSE;
 311 }
 312
 313 static gboolean on_key_press(GritsOpenGL *opengl, GdkEventKey *event, gpointer _)
 314 {
 315         g_debug("GritsOpenGL: on_key_press - key=%x, state=%x, plus=%x",
 316                         event->keyval, event->state, GDK_plus);
 317
 318         guint kv = event->keyval;
 319         /* Testing */
 320         if (kv == GDK_w) {
 321                 opengl->wireframe = !opengl->wireframe;
 322                 gtk_widget_queue_draw(GTK_WIDGET(opengl));
 323         }
 324 #ifdef ROAM_DEBUG
 325         else if (kv == GDK_n) roam_sphere_split_one(opengl->sphere);
 326         else if (kv == GDK_p) roam_sphere_merge_one(opengl->sphere);
 327         else if (kv == GDK_r) roam_sphere_split_merge(opengl->sphere);
 328         else if (kv == GDK_u) roam_sphere_update_errors(opengl->sphere);
 329         gtk_widget_queue_draw(GTK_WIDGET(opengl));
 330 #endif
 331         return FALSE;
 332 }
 333
 334 static gboolean on_chained_event(GritsOpenGL *opengl, GdkEvent *event, gpointer _)
 335 {
 336         _foreach_object(opengl, (GFunc)grits_object_event, event);
 337         return FALSE;
 338 }
 339
 340 static gboolean _update_errors_cb(gpointer _opengl)
 341 {
 342         GritsOpenGL *opengl = _opengl;
 343         g_mutex_lock(opengl->sphere_lock);
 344         roam_sphere_update_errors(opengl->sphere);
 345         g_mutex_unlock(opengl->sphere_lock);
 346         opengl->ue_source = 0;
 347         return FALSE;
 348 }
 349 static void on_view_changed(GritsOpenGL *opengl,
 350                 gdouble _1, gdouble _2, gdouble _3)
 351 {
 352         g_debug("GritsOpenGL: on_view_changed");
 353         _set_visuals(opengl);
 354 #ifndef ROAM_DEBUG
 355         if (!opengl->ue_source)
 356                 opengl->ue_source = g_idle_add_full(G_PRIORITY_HIGH_IDLE+30,
 357                                 _update_errors_cb, opengl, NULL);
 358         //roam_sphere_update_errors(opengl->sphere);
 359 #else
 360         (void)_update_errors_cb;
 361 #endif
 362 }
 363
 364 static gboolean on_idle(GritsOpenGL *opengl)
 365 {
 366         //g_debug("GritsOpenGL: on_idle");
 367         g_mutex_lock(opengl->sphere_lock);
 368         if (roam_sphere_split_merge(opengl->sphere))
 369                 gtk_widget_queue_draw(GTK_WIDGET(opengl));
 370         g_mutex_unlock(opengl->sphere_lock);
 371         return TRUE;
 372 }
 373
 374 static void on_realize(GritsOpenGL *opengl, gpointer _)
 375 {
 376         g_debug("GritsOpenGL: on_realize");
 377         gtk_gl_begin(GTK_WIDGET(opengl));
 378
 379         /* Connect signals and idle functions now that opengl is fully initialized */
 380         gtk_widget_add_events(GTK_WIDGET(opengl), GDK_KEY_PRESS_MASK);
 381         g_signal_connect(opengl, "configure-event",  G_CALLBACK(on_configure),    NULL);
 382         g_signal_connect(opengl, "expose-event",     G_CALLBACK(on_expose),       NULL);
 383
 384         g_signal_connect(opengl, "key-press-event",  G_CALLBACK(on_key_press),    NULL);
 385
 386         g_signal_connect(opengl, "location-changed", G_CALLBACK(on_view_changed), NULL);
 387         g_signal_connect(opengl, "rotation-changed", G_CALLBACK(on_view_changed), NULL);
 388
 389         g_signal_connect(opengl, "motion-notify-event", G_CALLBACK(on_motion_notify), NULL);
 390         g_signal_connect_after(opengl, "key-press-event",      G_CALLBACK(on_chained_event), NULL);
 391         g_signal_connect_after(opengl, "key-release-event",    G_CALLBACK(on_chained_event), NULL);
 392         g_signal_connect_after(opengl, "button-press-event",   G_CALLBACK(on_chained_event), NULL);
 393         g_signal_connect_after(opengl, "button-release-event", G_CALLBACK(on_chained_event), NULL);
 394         g_signal_connect_after(opengl, "motion-notify-event",  G_CALLBACK(on_chained_event), NULL);
 395
 396 #ifndef ROAM_DEBUG
 397         opengl->sm_source[0] = g_timeout_add_full(G_PRIORITY_HIGH_IDLE+30, 33,  (GSourceFunc)on_idle, opengl, NULL);
 398         opengl->sm_source[1] = g_timeout_add_full(G_PRIORITY_HIGH_IDLE+10, 500, (GSourceFunc)on_idle, opengl, NULL);
 399 #else
 400         (void)on_idle;
 401         (void)_update_errors_cb;
 402 #endif
 403
 404         /* Re-queue resize incase configure was triggered before realize */
 405         gtk_widget_queue_resize(GTK_WIDGET(opengl));
 406 }
 407
 408 /*********************
 409  * GritsViewer methods *
 410  *********************/
 411 /**
 412  * grits_opengl_new:
 413  * @plugins: the plugins store to use
 414  * @prefs:   the preferences object to use
 415  *
 416  * Create a new OpenGL renderer.
 417  *
 418  * Returns: the new #GritsOpenGL
 419  */
 420 GritsViewer *grits_opengl_new(GritsPlugins *plugins, GritsPrefs *prefs)
 421 {
 422         g_debug("GritsOpenGL: new");
 423         GritsViewer *opengl = g_object_new(GRITS_TYPE_OPENGL, NULL);
 424         grits_viewer_setup(opengl, plugins, prefs);
 425         return opengl;
 426 }
 427
 428 static void grits_opengl_center_position(GritsViewer *_opengl, gdouble lat, gdouble lon, gdouble elev)
 429 {
 430         glRotatef(lon, 0, 1, 0);
 431         glRotatef(-lat, 1, 0, 0);
 432         glTranslatef(0, 0, elev2rad(elev));
 433 }
 434
 435 static void grits_opengl_project(GritsViewer *_opengl,
 436                 gdouble lat, gdouble lon, gdouble elev,
 437                 gdouble *px, gdouble *py, gdouble *pz)
 438 {
 439         GritsOpenGL *opengl = GRITS_OPENGL(_opengl);
 440         gdouble x, y, z;
 441         lle2xyz(lat, lon, elev, &x, &y, &z);
 442         gluProject(x, y, z,
 443                 opengl->sphere->view->model,
 444                 opengl->sphere->view->proj,
 445                 opengl->sphere->view->view,
 446                 px, py, pz);
 447 }
 448
 449 static void grits_opengl_set_height_func(GritsViewer *_opengl, GritsBounds *bounds,
 450                 RoamHeightFunc height_func, gpointer user_data, gboolean update)
 451 {
 452         GritsOpenGL *opengl = GRITS_OPENGL(_opengl);
 453         /* TODO: get points? */
 454         g_mutex_lock(opengl->sphere_lock);
 455         GList *triangles = roam_sphere_get_intersect(opengl->sphere, TRUE,
 456                         bounds->n, bounds->s, bounds->e, bounds->w);
 457         for (GList *cur = triangles; cur; cur = cur->next) {
 458                 RoamTriangle *tri = cur->data;
 459                 RoamPoint *points[] = {tri->p.l, tri->p.m, tri->p.r, tri->split};
 460                 for (int i = 0; i < G_N_ELEMENTS(points); i++) {
 461                         if (bounds->n >= points[i]->lat && points[i]->lat >= bounds->s &&
 462                             bounds->e >= points[i]->lon && points[i]->lon >= bounds->w) {
 463                                 points[i]->height_func = height_func;
 464                                 points[i]->height_data = user_data;
 465                                 roam_point_update_height(points[i]);
 466                         }
 467                 }
 468         }
 469         g_list_free(triangles);
 470         g_mutex_unlock(opengl->sphere_lock);
 471 }
 472
 473 static void _grits_opengl_clear_height_func_rec(RoamTriangle *root)
 474 {
 475         if (!root)
 476                 return;
 477         RoamPoint *points[] = {root->p.l, root->p.m, root->p.r, root->split};
 478         for (int i = 0; i < G_N_ELEMENTS(points); i++) {
 479                 points[i]->height_func = NULL;
 480                 points[i]->height_data = NULL;
 481                 roam_point_update_height(points[i]);
 482         }
 483         _grits_opengl_clear_height_func_rec(root->kids[0]);
 484         _grits_opengl_clear_height_func_rec(root->kids[1]);
 485 }
 486
 487 static void grits_opengl_clear_height_func(GritsViewer *_opengl)
 488 {
 489         GritsOpenGL *opengl = GRITS_OPENGL(_opengl);
 490         for (int i = 0; i < G_N_ELEMENTS(opengl->sphere->roots); i++)
 491                 _grits_opengl_clear_height_func_rec(opengl->sphere->roots[i]);
 492 }
 493
 494 static gpointer grits_opengl_add(GritsViewer *_opengl, GritsObject *object,
 495                 gint key, gboolean sort)
 496 {
 497         g_assert(GRITS_IS_OPENGL(_opengl));
 498         GritsOpenGL *opengl = GRITS_OPENGL(_opengl);
 499         g_mutex_lock(opengl->objects_lock);
 500         struct RenderLevel *level = g_tree_lookup(opengl->objects, (gpointer)(gintptr)key);
 501         if (!level) {
 502                 level = g_new0(struct RenderLevel, 1);
 503                 g_tree_insert(opengl->objects, (gpointer)(gintptr)key, level);
 504         }
 505         GList *list = sort ? &level->sorted : &level->unsorted;
 506         /* Put the link in the list */
 507         GList *link = g_new0(GList, 1);
 508         link->data = object;
 509         link->prev = list;
 510         link->next = list->next;
 511         if (list->next)
 512                 list->next->prev = link;
 513         list->next = link;
 514         g_mutex_unlock(opengl->objects_lock);
 515         return link;
 516 }
 517
 518 static GritsObject *grits_opengl_remove(GritsViewer *_opengl, GritsObject *object)
 519 {
 520         g_assert(GRITS_IS_OPENGL(_opengl));
 521         GritsOpenGL *opengl = GRITS_OPENGL(_opengl);
 522         GList *link = object->ref;
 523         g_mutex_lock(opengl->objects_lock);
 524         /* Just unlink and free it, link->prev is assured */
 525         link->prev->next = link->next;
 526         if (link->next)
 527                 link->next->prev = link->prev;
 528         g_mutex_unlock(opengl->objects_lock);
 529         object->ref    = NULL;
 530         object->viewer = NULL;
 531         g_free(link);
 532         g_object_unref(object);
 533         return object;
 534 }
 535
 536 /****************
 537  * GObject code *
 538  ****************/
 539 static int _objects_cmp(gconstpointer _a, gconstpointer _b, gpointer _)
 540 {
 541         gintptr a = (gintptr)_a, b = (gintptr)_b;
 542         return a < b ? -1 :
 543                a > b ?  1 : 0;
 544 }
 545 static void _objects_free(gpointer value)
 546 {
 547         struct RenderLevel *level = value;
 548         if (level->sorted.next)
 549                 g_list_free(level->sorted.next);
 550         if (level->unsorted.next)
 551                 g_list_free(level->unsorted.next);
 552         g_free(level);
 553 }
 554
 555 G_DEFINE_TYPE(GritsOpenGL, grits_opengl, GRITS_TYPE_VIEWER);
 556 static void grits_opengl_init(GritsOpenGL *opengl)
 557 {
 558         g_debug("GritsOpenGL: init");
 559         opengl->objects      = g_tree_new_full(_objects_cmp, NULL, NULL, _objects_free);
 560         opengl->objects_lock = g_mutex_new();
 561         opengl->sphere       = roam_sphere_new(opengl);
 562         opengl->sphere_lock  = g_mutex_new();
 563         gtk_gl_enable(GTK_WIDGET(opengl));
 564         gtk_widget_add_events(GTK_WIDGET(opengl), GDK_KEY_PRESS_MASK);
 565         g_signal_connect(opengl, "map", G_CALLBACK(on_realize), NULL);
 566 }
 567 static void grits_opengl_dispose(GObject *_opengl)
 568 {
 569         g_debug("GritsOpenGL: dispose");
 570         GritsOpenGL *opengl = GRITS_OPENGL(_opengl);
 571         if (opengl->sm_source[0]) {
 572                 g_source_remove(opengl->sm_source[0]);
 573                 opengl->sm_source[0] = 0;
 574         }
 575         if (opengl->sm_source[1]) {
 576                 g_source_remove(opengl->sm_source[1]);
 577                 opengl->sm_source[1] = 0;
 578         }
 579         if (opengl->ue_source) {
 580                 g_source_remove(opengl->ue_source);
 581                 opengl->ue_source = 0;
 582         }
 583         G_OBJECT_CLASS(grits_opengl_parent_class)->dispose(_opengl);
 584 }
 585 static void grits_opengl_finalize(GObject *_opengl)
 586 {
 587         g_debug("GritsOpenGL: finalize");
 588         GritsOpenGL *opengl = GRITS_OPENGL(_opengl);
 589         roam_sphere_free(opengl->sphere);
 590         g_tree_destroy(opengl->objects);
 591         g_mutex_free(opengl->objects_lock);
 592         g_mutex_free(opengl->sphere_lock);
 593         G_OBJECT_CLASS(grits_opengl_parent_class)->finalize(_opengl);
 594 }
 595 static void grits_opengl_class_init(GritsOpenGLClass *klass)
 596 {
 597         g_debug("GritsOpenGL: class_init");
 598         GObjectClass *gobject_class = G_OBJECT_CLASS(klass);
 599         gobject_class->finalize = grits_opengl_finalize;
 600         gobject_class->dispose = grits_opengl_dispose;
 601
 602         GritsViewerClass *viewer_class = GRITS_VIEWER_CLASS(klass);
 603         viewer_class->center_position   = grits_opengl_center_position;
 604         viewer_class->project           = grits_opengl_project;
 605         viewer_class->clear_height_func = grits_opengl_clear_height_func;
 606         viewer_class->set_height_func   = grits_opengl_set_height_func;
 607         viewer_class->add               = grits_opengl_add;
 608         viewer_class->remove            = grits_opengl_remove;
 609 }