Activate depth buffer when the GL context is created.

src/gtk/glmapview.cpp

@@ -30,6 +30,7 @@ GlMapView::GlMapView(GtkBuilder *builder)
         GDK_GL_RED_SIZE, 1,
         GDK_GL_GREEN_SIZE, 1,
         GDK_GL_BLUE_SIZE, 1,
+        GDK_GL_DEPTH_SIZE, 16,
         GDK_GL_DOUBLEBUFFER,
         GDK_GL_NONE
     };

src/scene.cpp

@@ -99,7 +99,7 @@ void Scene::Render() // XXX: rename to Blit()
     static float f = 0.0f;
     f += 0.05f;
     glTranslatef(320.0f, 240.0f, 0.0f);
-    glRotatef(45.0f, 1.0f, 0.0f, 0.0f);
+    glRotatef(-45.0f, 1.0f, 0.0f, 0.0f);
 #if 0
     glRotatef(3.0f * sinf(f), 1.0f, 0.0f, 0.0f);
     glRotatef(8.0f * cosf(f), 0.0f, 0.0f, 1.0f);

src/test-map.cpp

@@ -30,6 +30,8 @@ int main(int argc, char **argv)
         return EXIT_FAILURE;
     }
 
+    SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);
+    SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, 16);
     SDL_Surface *video = SDL_SetVideoMode(640, 480, 0, SDL_OPENGL);
     if (!video)
     {