constant scale for perspective

[grits] / src / opengl.c

diff --git a/src/opengl.c b/src/opengl.c
index 9a369eca3afb096bb7c0a08bc8a0faedfacf44a6..09b41d5fa1aa8354d3bc41ebb2007542538a8f44 100644 (file)
--- a/src/opengl.c
+++ b/src/opengl.c
@@ -1,10 +1,13 @@
 #include <config.h>
+#include <math.h>
 #include <gtk/gtk.h>
 #include <gtk/gtkgl.h>
 #include <GL/gl.h>
+#include <GL/glu.h>
 
 static gboolean expose_start(GtkWidget *da, GdkEventExpose *event, gpointer user_data)
 {
+       g_message("opengl:expose_start");
        GdkGLContext *glcontext = gtk_widget_get_gl_context(da);
        GdkGLDrawable *gldrawable = gtk_widget_get_gl_drawable(da);
 
@@ -19,6 +22,8 @@ static gboolean expose_start(GtkWidget *da, GdkEventExpose *event, gpointer user
 /* Plugins run stuff here */
 static gboolean expose_end(GtkWidget *da, GdkEventExpose *event, gpointer user_data)
 {
+       g_message("opengl:expose_end");
+
        GdkGLDrawable *gldrawable = gtk_widget_get_gl_drawable(da);
 
        if (gdk_gl_drawable_is_double_buffered(gldrawable))
@@ -38,14 +43,25 @@ static gboolean configure_start(GtkWidget *da, GdkEventConfigure *event, gpointe
        if (!gdk_gl_drawable_gl_begin(gldrawable, glcontext))
                g_assert_not_reached();
 
-       glLoadIdentity();
-       glViewport(0, 0, da->allocation.width, da->allocation.height);
+
+       double width  = da->allocation.width;
+       double height = da->allocation.height;
+       double dist   = 500*1000; // 500 km
+       glViewport(0, 0, width, height);
+
        glEnable(GL_BLEND);
        glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
-       //glEnable(GL_ALPHA_TEST);
-       //glAlphaFunc(GL_EQUAL, 0);
-       double scale = 500*1000; // 500 km
-       glOrtho(-scale,scale,-scale,scale,0,10000);
+
+       glMatrixMode(GL_PROJECTION);
+       glLoadIdentity();
+       double rad = atan(height/2*1000.0/dist); // 1px = 1000 meters
+       double deg = (rad*180)/M_PI;
+       gluPerspective(deg*2, width/height, 0.1f, 10000000.0f);
+
+       glMatrixMode(GL_MODELVIEW);
+       glLoadIdentity();
+       glTranslatef(0.0, 0.0, -dist);
+       glRotatef(-45, 1, 0, 0);
 
        return FALSE;
 }