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\n");
  26
  27         GdkGLDrawable *gldrawable = gdk_gl_drawable_get_current();
  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
  51         /* Misc */
  52         glViewport(0, 0, width, height);
  53         glEnable(GL_BLEND);
  54         glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
  55         glClearColor(0.8f, 0.8f, 1.0f, 0.0f);
  56
  57         /* Tessellation, "finding intersecting triangles" */
  58         /* http://research.microsoft.com/pubs/70307/tr-2006-81.pdf */
  59         /* http://www.opengl.org/wiki/Alpha_Blending */
  60         glAlphaFunc(GL_GREATER,0.1);
  61         glEnable(GL_ALPHA_TEST);
  62
  63         /* Depth test */
  64         glClearDepth(1.0);
  65         glDepthFunc(GL_LEQUAL);
  66         glEnable(GL_DEPTH_TEST);
  67
  68         /* Perspective */
  69         glMatrixMode(GL_PROJECTION);
  70         glLoadIdentity();
  71         double rad = atan(height/2*1000.0/dist); // 1px = 1000 meters
  72         double deg = (rad*180)/M_PI;
  73         gluPerspective(deg*2, width/height, dist-20, dist+20);
  74
  75         /* Camera position? */
  76         glMatrixMode(GL_MODELVIEW);
  77         glLoadIdentity();
  78         glTranslatef(0.0, 0.0, -dist);
  79         //glRotatef(-45, 1, 0, 0);
  80
  81
  82         return FALSE;
  83 }
  84 static gboolean configure_end(GtkWidget *da, GdkEventConfigure *event, gpointer user_data)
  85 {
  86         GdkGLDrawable *gldrawable = gdk_gl_drawable_get_current();
  87         gdk_gl_drawable_gl_end(gldrawable);
  88         return FALSE;
  89 }
  90
  91 gboolean opengl_init(GtkDrawingArea *drawing, GtkNotebook *config)
  92 {
  93         /* Set up OpenGL Stuff */
  94         g_signal_connect      (drawing, "configure-event", G_CALLBACK(configure_start), NULL);
  95         g_signal_connect_after(drawing, "configure-event", G_CALLBACK(configure_end),   NULL);
  96         g_signal_connect      (drawing, "expose-event",    G_CALLBACK(expose_start),    NULL);
  97         g_signal_connect_after(drawing, "expose-event",    G_CALLBACK(expose_end),      NULL);
  98         return TRUE;
  99 }