Node editor window

Access to Blender nodes is via a new window type, the "Node Editor". It is available in the default left-most button in every Blender window header.

 

The context of the Node Editor is defined by the first two icons in the header; which currently showsthe options for Material Nodes or Scene (Composite) Nodes.

 

The Material Nodes, as shown in the Node Editor, work like the buttons window, in that it is based on the active Object and its active "Material index" (in the case that multiple Materials are available on the Object).

 

Since Nodes are a new feature, you will also have to enable them with the "Use Nodes" button. This button can also be used to temporally disable shading or compositing recalculations while working with Nodes.

Node display options

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Nodes have several options for display:

 

1) The default Node shows everything. For each input socket not in use, a button is displayed, which allows the manual setting of variables for inputs.

2) These Input buttons disappear when Inputs are in use

3) The (+) icon hides unused sockets.

4) The 'buttons' icon will hide the optional Node buttons.

5) The red sphere icon hides the preview and disables preview rendering

6) The triangle icon will draw the entire node "hidden" (hotkey H)

 

The bottom-right corner allows the Node to be scaled.

Same Node, different scale

Design evaluation

As you can see in the above images, a Node is drawn starting with its header, then the outputs are drawn, then a Preview, then the button options, and lastly the inputs. This order is relatively arbitrary, but some reasoning can be mentioned for it:

  • Typically there are only few outputs, and many inputs, thus drawing outputs first gives a more consistant looking layout.
  • The input sockets, if not in use, give button options. This looks better if they are combined with the Node button options themselves.
  • If you scale a Node, small or large, it should, in as many cases as possible, result in a scaled preview, with the least amount of unused space ('white space').
  • Previews can have any aspect ratio (like Images for Compositing), which work best if it can align with the Node borders.

 

This top/down priority approach has been implemented for defining operation order. For example the "Mix Node" has 2 color input sockets. The top socket is passed on by default, and the "Factor" input defines how much the second input accounts for (0.0 = no influence).

 

This has been implemented consistantly throughout the entire Node system, which explains why the "Alpha Over" Node demands that the first (top) socket be the background. :)

 

Note: in the Compositor the first (top) input socket also defines the size of the resulting output image.

Links

You add links by dragging a line from one socket to anotherm with LeftMouse. Linking rules are:

  • Outputs can have an unlimited number of links.
  • Inputs only allow a single link.
  • You cannot link a Node to itself.
  • When dragging a link from an Output socket to an Input socket, the existing link for this Input is either removed, or moved to another free Input socket
  • When dragging a link starting from an Input that has a link, you will be able to reconnect (or remove) this link
  • When a link turns red, there's a cyclic dependency conflict. You can press Ckey to see all cyclic links in succession.

 

To remove links, drag the LeftMouse in the window background, the cursor changes to a knife, and all links that are intersected by the rectangle you draw are removed.

Editing (hotkey) options

Most editing options are available via Hotkeys, the Toolbox (Spacebar) or with pulldown menus in header (to be done).

  • Left mouse: (de)select Node, drag nodes, drag links, use buttons or remove links.
  • Middle mouse: drag view, or zoom in/out whilst holding CTRL .
  • Right mouse: (de)select Node, Grab Node (with hold-drag)


  • Akey: (de)select All
  • SHIFT+A: Add Nodes
  • Bkey: Border (de)select
  • Ckey: Solve dependencies, and show conflict(s)
  • Shift+D: Add duplicate of selection
  • Gkey: Grab Nodes
  • CTRL+G: Create Group
  • ALT+G: Ungroup
  • SHIFT+G: Add group
  • Hkey: Hide/unhide selection (hiding here is actually "minimize")
  • Rkey: Compositor option - if the render option "Save Buffers" is used, it reads the buffers and executes a Composite.
  • Xkey: Delete selection


  • Tab: Enter or Leave editing group mode.
  • Home: View all
  • Pad Plus/Minus: Zoom in/out
  • Delete key: Delete selection

Undo

The node editor supports undo/redo for all changes, but the (composite/shader) results or preview images are not saved. To keep undo/redo interactive, no recalculations happen automatically either, you have to invoke that by causing a recalculation yourself (press an input socket).

 


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