Viewer node (as in animation nodes)

Most node-based systems use the properties window to control the properties of the nodes, and the nodes themselves to drive values or give a preview of a texture etc. Blender has the values on the nodes themselves, which I like, but this takes away the ability to preview a texture or debug a value that was driven by another node. We do see a little bit of this, however, in the compositing window, where you get a tiny window that gives a preview of a texture. But this is not being used to it’s full potential. Say you had a bunch of math nodes. You want to be able to debug it, to make sure your value is the value you want it to be. You plug the value into a debug node, and it shows you the value. Animation nodes already has such a node (see thumbnail), which is so useful, when you get into complex nodetrees.

This could easily be implemented into every node editor, with additional debugging features such as:

• Showing a color preview and hsv value when a color is plugged in
• Showing a texture when a texture is plugged in
• Showing a vector preview in the 3d viewport when selected and the vector’s value when a vector is plugged in
• Showing the shader preview when a shader is plugged in (the same shader preview in the properties window)
• Showing a geometry preview in the viewport when selected
• Showing the name, type and value of an attribute when an attribute is plugged in

This would allow you to see things in the middle of your nodetree, and will be essential in the future.