Pileus Git - grits/blob - src/objects/grits-object.c

   1 /*
   2  * Copyright (C) 2009-2010 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-object
  20  * @short_description: Base class for drawing operations
  21  *
  22  * Objects in grits are things which can be added to the viewer and will be
  23  * displayed to the user. Each object has information such as it's location and
  24  * level of detail which are used by the viewer to determine which objects
  25  * should be drawn.
  26  *
  27  * Each #GritsObject is also a #GObject, but not every GObject in grits is a
  28  * GritsObject. The "Object" part of the name is just coincidence.
  29  */
  30
  31 #include <config.h>
  32 #include <math.h>
  33 #include <GL/gl.h>
  34
  35 #include "grits-object.h"
  36
  37
  38 /**
  39  * grits_object_draw:
  40  * @object: the object
  41  * @opengl: the viewer the object is being displayed in
  42  *
  43  * Perform any OpenGL commands necessasairy to draw the object.
  44  *
  45  * The GL_PROJECTION and GL_MODELVIEW matricies and GL_ALL_ATTRIB_BITS will be
  46  * restored to the default state after the call to draw.
  47  */
  48 void grits_object_draw(GritsObject *object, GritsOpenGL *opengl)
  49 {
  50         GritsObjectClass *klass = GRITS_OBJECT_GET_CLASS(object);
  51         if (!klass->draw) {
  52                 g_warning("GritsObject: draw - Unimplemented");
  53                 return;
  54         }
  55
  56         /* Skip hidden objects */
  57         if (object->hidden)
  58                 return;
  59
  60         /* Support GritsTester */
  61         if (!GRITS_IS_OPENGL(opengl)) {
  62                 g_debug("GritsObject: draw - drawing raw object");
  63                 klass->draw(object, opengl);
  64                 return;
  65         }
  66
  67         /* Calculae distance for LOD and horizon tests */
  68         GritsPoint *center = &object->center;
  69         if ((!(object->skip & GRITS_SKIP_LOD) ||
  70              !(object->skip & GRITS_SKIP_HORIZON)) &&
  71             (center->elev != -EARTH_R)) {
  72                 /* LOD test */
  73                 gdouble eye[3], obj[3];
  74                 grits_viewer_get_location(GRITS_VIEWER(opengl),
  75                                 &eye[0], &eye[1], &eye[2]);
  76                 gdouble elev = eye[2];
  77                 lle2xyz(eye[0], eye[1], eye[2],
  78                                 &eye[0], &eye[1], &eye[2]);
  79                 lle2xyz(center->lat, center->lon, center->elev,
  80                                 &obj[0], &obj[1], &obj[2]);
  81                 gdouble dist = distd(obj, eye);
  82
  83                 /* Level of detail test */
  84                 if (!(object->skip & GRITS_SKIP_LOD)
  85                                 && object->lod > 0) {
  86                         if (object->lod < dist)
  87                                 return;
  88                 }
  89
  90                 /* Horizon test */
  91                 if (!(object->skip & GRITS_SKIP_HORIZON)) {
  92                         gdouble c = EARTH_R+elev;
  93                         gdouble a = EARTH_R;
  94                         gdouble horizon = sqrt(c*c - a*a);
  95                         if (dist > horizon)
  96                                 return;
  97                 }
  98         }
  99
 100         /* Save state, draw, restore state */
 101         g_mutex_lock(opengl->sphere_lock);
 102         if (!(object->skip & GRITS_SKIP_STATE)) {
 103                 glPushAttrib(GL_ALL_ATTRIB_BITS);
 104                 glMatrixMode(GL_PROJECTION); glPushMatrix();
 105                 glMatrixMode(GL_MODELVIEW);  glPushMatrix();
 106         }
 107
 108         if (!(object->skip & GRITS_SKIP_CENTER))
 109                 grits_viewer_center_position(GRITS_VIEWER(opengl),
 110                                 object->center.lat,
 111                                 object->center.lon,
 112                                 object->center.elev);
 113
 114         klass->draw(object, opengl);
 115
 116         if (!(object->skip & GRITS_SKIP_STATE)) {
 117                 glPopAttrib();
 118                 glMatrixMode(GL_PROJECTION); glPopMatrix();
 119                 glMatrixMode(GL_MODELVIEW);  glPopMatrix();
 120         }
 121         g_mutex_unlock(opengl->sphere_lock);
 122 }
 123
 124 void grits_object_queue_draw(GritsObject *object)
 125 {
 126         if (object->viewer)
 127                 gtk_widget_queue_draw(GTK_WIDGET(object->viewer));
 128 }
 129
 130 /* GObject stuff */
 131 G_DEFINE_ABSTRACT_TYPE(GritsObject, grits_object, G_TYPE_OBJECT);
 132 static void grits_object_init(GritsObject *object)
 133 {
 134         object->center.lat  =  0;
 135         object->center.lon  =  0;
 136         object->center.elev = -EARTH_R;
 137 }
 138
 139 static void grits_object_class_init(GritsObjectClass *klass)
 140 {
 141 }