+ /** Sets the fog color, which is blended into distant surfaces. */
+ void set_fog_color(const Color &);
+
+ /** Sets the density of the fog. Zero means no fog. */
+ void set_fog_density(float);
+
+ /** Sets the density of the fog so that the blending factor at the given
+ distance is 50%. */
+ void set_fog_half_distance(float);
+