   Texturing Fog Volume
  Is there any way to texture fog volume. I am thinking about some noise texture to fake different densities through fog volume. What would be the appropriate way to do this.Thanx   
  If you're already rendering deferred? Use a function of depth as the alpha for a texture.If you're not rendering deferred? Render a second layer, probably at a lower resolution (say, 1/4 screen res), rendering your scene only as flat white on all surfaces with a black fog. Use this layer as the alpha map to draw your "fog" texture over the scene.If you've got volumetric fog, then you've already got everything you need. Just draw a texture instead of a solid colour.   ;  Which fog volume technique are you using? Do you draw the bounding-geometry of the volume?The "correct" way would be to use a 3D texture and ray-march it... but it usually looks ok if you just evaluate a 2D texture on the surface of the volume.   ;  I'm not sure what I think of as volumetric fog is correct, but if it is...Within the volume fog shader, sample a grayscale volume texture (tex3D) using world position as UVW coordinates. Multiply fog strength by the sample.For extra cool points, sample the fog texture and offset coordinates by time.For extra extra cool points, sample the fog texture twice - with UVW coordinates inverted and moving towards eachother (think water shader) and multiply the result. Then multiply fog strength by the result.   