How to create a fog effect

Beginners
1

Hi,

I am looking for suggestions on how to make a basic Fog effect (wisps of semi-transparent smoke).

My original thought was to make a rectangle SOP and apply a noise TOP to it via a PHONG, then use another noise TOP as the alpha map of the PHONG.

However, it seems, even with an alpha map, making the SOP have a transparency of 0, doesn’t actually make the SOP transparent, but rather it makes it black(?).

So, simply put, how could I make a transparent Rectangle sop? I’d also be interested in other Fog options (I am assuming that a particle system would be great here) - I don’t need examples I am just curious about what is the most legit way would be done.

2

Check out this article on transparency
derivative.ca/wiki088/index. … ansparency

3

Wow that was fun,
About five minutes with that article and I got the desired result (way to go render pass and the blending parameter) (you can kind of see fog / smoke at the bottom of this screengrab)

Hot damn I love Touch.

Just to clarify though:

When the article says

Is the general idea to have two (or at least two) geometry COMPs and Cameras (one for your transparent and one for your non-transparent SOPs)?

In other words when it says “draw” is it referring to rendering via a dedicated Camera and Geo?