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

   1 #include <config.h>
   2 #include <math.h>
   3 #include <gtk/gtk.h>
   4 #include <gtk/gtkgl.h>
   5 #include <GL/gl.h>
   6 #include <GL/glu.h>
   7
   8 static gboolean expose_start(GtkWidget *da, GdkEventExpose *event, gpointer user_data)
   9 {
  10         g_message("opengl:expose_start");
  11         GdkGLContext *glcontext = gtk_widget_get_gl_context(da);
  12         GdkGLDrawable *gldrawable = gtk_widget_get_gl_drawable(da);
  13
  14         if (!gdk_gl_drawable_gl_begin(gldrawable, glcontext)) {
  15                 g_assert_not_reached();
  16         }
  17
  18         /* draw in here */
  19         glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
  20         return FALSE;
  21 }
  22 /* Plugins run stuff here */
  23 static gboolean expose_end(GtkWidget *da, GdkEventExpose *event, gpointer user_data)
  24 {
  25         g_message("opengl:expose_end");
  26
  27         GdkGLDrawable *gldrawable = gtk_widget_get_gl_drawable(da);
  28
  29         if (gdk_gl_drawable_is_double_buffered(gldrawable))
  30                 gdk_gl_drawable_swap_buffers(gldrawable);
  31         else
  32                 glFlush();
  33
  34         gdk_gl_drawable_gl_end(gldrawable);
  35
  36         return FALSE;
  37 }
  38 static gboolean configure_start(GtkWidget *da, GdkEventConfigure *event, gpointer user_data)
  39 {
  40         GdkGLContext  *glcontext  = gtk_widget_get_gl_context(da);
  41         GdkGLDrawable *gldrawable = gtk_widget_get_gl_drawable(da);
  42
  43         if (!gdk_gl_drawable_gl_begin(gldrawable, glcontext))
  44                 g_assert_not_reached();
  45
  46
  47         double width  = da->allocation.width;
  48         double height = da->allocation.height;
  49         double dist   = 500*1000; // 500 km
  50         glViewport(0, 0, width, height);
  51
  52         glEnable(GL_BLEND);
  53         glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
  54
  55         glMatrixMode(GL_PROJECTION);
  56         glLoadIdentity();
  57         double rad = atan(height/2*1000.0/dist); // 1px = 1000 meters
  58         double deg = (rad*180)/M_PI;
  59         gluPerspective(deg*2, width/height, 0.1f, 10000000.0f);
  60
  61         glMatrixMode(GL_MODELVIEW);
  62         glLoadIdentity();
  63         glTranslatef(0.0, 0.0, -dist);
  64         glRotatef(-45, 1, 0, 0);
  65
  66         return FALSE;
  67 }
  68 static gboolean configure_end(GtkWidget *da, GdkEventConfigure *event, gpointer user_data)
  69 {
  70         GdkGLDrawable *gldrawable = gtk_widget_get_gl_drawable(da);
  71         gdk_gl_drawable_gl_end(gldrawable);
  72         return FALSE;
  73 }
  74
  75 gboolean opengl_init(GtkDrawingArea *drawing, GtkNotebook *config)
  76 {
  77         /* Set up OpenGL Stuff */
  78         g_signal_connect      (drawing, "configure-event", G_CALLBACK(configure_start), NULL);
  79         g_signal_connect_after(drawing, "configure-event", G_CALLBACK(configure_end),   NULL);
  80         g_signal_connect      (drawing, "expose-event",    G_CALLBACK(expose_start),    NULL);
  81         g_signal_connect_after(drawing, "expose-event",    G_CALLBACK(expose_end),      NULL);
  82         return TRUE;
  83 }