On the Blender wiki and many video tutorials on nodes, there is a preview pane in each node. I am using 2.66 and my nodes show no preview panes and no buttons (as per wiki) that would toggle them on. Where are these? Thanks
I might be wrong but I think you have compositing mixed up with mat nodes (they look a lot alike)
the compositor does have the preview window but as far as I know the only way to check a mat node setup is to do a test render
(easy if you have a nvida gpu)
BI does have an output node that can be plugged anywhere in the node group to give a preview of the material at that point.
For example - if you mix an RGB node with a texture - you can insert an output node after the mix to see the result - before passing this mixture through to your material. It allows you to track the progress of your material as its being built up by the node group.
There is no equivalent in cycles however (shame - as it is useful)
Whenever I experiment with node materials, I split the window pane and have one half set to 3D view in rendered preview. When doing that, it’s probably best to view the mesh with the material being applied by itself rather than show the whole scene.
Not quite a preview panel, but close enough to be useful in the same regard. Just keep preview samples low so it updates fast. (The default value of 10 seems to work well in most cases.)
I think I may have confused Blender Render Material nodes with Blender Cycles Material nodes. They are not the same list and found they are not interchangeable. Thanks for all the replies. I would like to mark this solved but do not know how.