25 times? I just came up to 4-5 times, rendering with the preview tool. In the renderwindow I have got an error. So I give up testing. But what is to see, on other renders, that the fog does not recieve shadows from other objects. That would be the basis to get rays. And to give the fog a glowparameter. If this glowparameter would be connected to the sun, like the shoestringshader, you would get fantastic glowing fog, with rays and shadows. And the cloudshadows have no control, to set the intensity of the shadows, I do not mean the selfshadows, but the shadows in the secene. Do they depend on the cloudcolour? A glowparameter would give those clouds the abibility, to glow, if they appear near the sun, like they do in nature. Okay, thats much, but thats what I am really missing. Johannes