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 #include "aweather-gui.h"
   9
  10 static gboolean expose_start(GtkWidget *da, GdkEventExpose *event, gpointer user_data)
  11 {
  12         g_message("opengl:expose_start");
  13         GdkGLContext *glcontext = gtk_widget_get_gl_context(da);
  14         GdkGLDrawable *gldrawable = gtk_widget_get_gl_drawable(da);
  15
  16         if (!gdk_gl_drawable_gl_begin(gldrawable, glcontext)) {
  17                 g_assert_not_reached();
  18         }
  19
  20         /* draw in here */
  21         glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
  22         return FALSE;
  23 }
  24 /* Plugins run stuff here */
  25 static gboolean expose_end(GtkWidget *da, GdkEventExpose *event, gpointer user_data)
  26 {
  27         g_message("opengl:expose_end\n");
  28
  29         GdkGLDrawable *gldrawable = gdk_gl_drawable_get_current();
  30
  31         if (gdk_gl_drawable_is_double_buffered(gldrawable))
  32                 gdk_gl_drawable_swap_buffers(gldrawable);
  33         else
  34                 glFlush();
  35
  36         gdk_gl_drawable_gl_end(gldrawable);
  37
  38         return FALSE;
  39 }
  40 static gboolean configure_start(GtkWidget *da, GdkEventConfigure *event, gpointer user_data)
  41 {
  42         g_message("opengl:configure_start");
  43         GdkGLContext  *glcontext  = gtk_widget_get_gl_context(da);
  44         GdkGLDrawable *gldrawable = gtk_widget_get_gl_drawable(da);
  45
  46         if (!gdk_gl_drawable_gl_begin(gldrawable, glcontext))
  47                 g_assert_not_reached();
  48
  49
  50         double width  = da->allocation.width;
  51         double height = da->allocation.height;
  52         double dist   = 500*1000; // 500 km
  53
  54         /* Misc */
  55         glViewport(0, 0, width, height);
  56         glEnable(GL_BLEND);
  57         glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
  58         glClearColor(0.8f, 0.8f, 1.0f, 0.0f);
  59
  60         /* Tessellation, "finding intersecting triangles" */
  61         /* http://research.microsoft.com/pubs/70307/tr-2006-81.pdf */
  62         /* http://www.opengl.org/wiki/Alpha_Blending */
  63         glAlphaFunc(GL_GREATER,0.1);
  64         glEnable(GL_ALPHA_TEST);
  65
  66         /* Depth test */
  67         glClearDepth(1.0);
  68         glDepthFunc(GL_LEQUAL);
  69         glEnable(GL_DEPTH_TEST);
  70
  71         /* Perspective */
  72         glMatrixMode(GL_PROJECTION);
  73         glLoadIdentity();
  74         double rad = atan(height/2*1000.0/dist); // 1px = 1000 meters
  75         double deg = (rad*180)/M_PI;
  76         gluPerspective(deg*2, width/height, dist-20, dist+20);
  77
  78         /* Camera position? */
  79         glMatrixMode(GL_MODELVIEW);
  80         glLoadIdentity();
  81         glTranslatef(0.0, 0.0, -dist);
  82         //glRotatef(-45, 1, 0, 0);
  83
  84
  85         return FALSE;
  86 }
  87 static gboolean configure_end(GtkWidget *da, GdkEventConfigure *event, gpointer user_data)
  88 {
  89         g_message("opengl:configure_end");
  90         GdkGLDrawable *gldrawable = gdk_gl_drawable_get_current();
  91         gdk_gl_drawable_gl_end(gldrawable);
  92         return FALSE;
  93 }
  94
  95 gboolean opengl_init(AWeatherGui *gui)
  96 {
  97         GtkDrawingArea *drawing = aweather_gui_get_drawing(gui);
  98
  99         GdkGLConfig *glconfig = gdk_gl_config_new_by_mode(
 100                         GDK_GL_MODE_RGBA   | GDK_GL_MODE_DEPTH |
 101                         GDK_GL_MODE_DOUBLE | GDK_GL_MODE_ALPHA);
 102         if (!glconfig)
 103                 g_error("Failed to create glconfig");
 104         if (!gtk_widget_set_gl_capability(GTK_WIDGET(drawing), glconfig, NULL, TRUE, GDK_GL_RGBA_TYPE))
 105                 g_error("GL lacks required capabilities");
 106
 107         /* Set up OpenGL Stuff */
 108         g_signal_connect      (drawing, "configure-event", G_CALLBACK(configure_start), NULL);
 109         g_signal_connect_after(drawing, "configure-event", G_CALLBACK(configure_end),   NULL);
 110         g_signal_connect      (drawing, "expose-event",    G_CALLBACK(expose_start),    NULL);
 111         g_signal_connect_after(drawing, "expose-event",    G_CALLBACK(expose_end),      NULL);
 112         return TRUE;
 113 }