Making and Breaking Connections in the Hypergraph
One of the most interesting features of the Hypergraph is its ability to make and break data connections between nodes. To see how this works, take our example scene (the ball and hat), and add a lattice deformer to the ball (select the ball node, then choose Deform > Create Lattice). Select the ball node again, and choose Graph > Up and Downstream Connections. In this new view, you will see connecting arrows between the nodes that make up the lattice-ball group. By passing your cursor over one of these arrows, you can see the output/input data connections between nodes.
To break one of these connections, just click on one of the arrows (highlighting it yellow) and hit the Delete key. You can, for example, break the deformer connection between the lattice and the ball if you highlight the arrow that shows the ffdILatticeShape.latticeOutput to ffdl.deformedLatticePoints connection (the one shown in the image above). If you alter the deformer (scale it, say), you will immediately see the ball return to its original shape when you delete the connection.
Tip As should be obvious, it is dangerous to go around deleting connections between nodes □especially if you donnt know what younre doing. This is not to say you shouldnnt experiment; just save your file before you do start deleting connections, so in case you cannt get what you want, you can at least return to a good version of your project.
To make a connection between nodes, just MM drag one node on top of another (the node that will output a value will be the one you drag; the one that will accept an input value will be the node you drag onto). Once you have completed the drag operation, the Connection Editor will open, allowing you to choose which attributes to connect. If, for example, you MM drag ffdILattice onto ball, you might connect the latticens visibility attribute to the ballns visibility (click on each of these attributes on the right and left of the Connection Editor to connect them). Then, when you hide the lattice, the ball will hide as well. To confirm that the connection has been made, you will see a new arrow in the Hypergraph showing the connected attributes.
In general, most people use the Hypergraph (and now the Hypershade as well) primarily to make and break connections between shader nodes in a shader network, such as the luminance output of a texture being fed into the transparency of a material node. While the connected attributes are different, however, the method of making and breaking connections is the same as described above.
The Ins and Outs of the Connection Editor
The Connection Editor is an extremely useful Maya feature. Essentially, it lets you connect any output of one node to any matching (that is, of the same data type) input of another node. The Connection Editor can do some amazing things, connecting even the most bizarre attributes (as long as their data types match). This base-level control over connections gives you creative control over anything from ramp texture colors to object rotation order based on another objectns position (or that of another node on the same object), visibility, node state, or whatever else you can dream up. In shader networks, the output color of one node (like a fractal map) is often automatically input into the input color of another node (like a phongE texture) when you create a texture map. With the Connection Editor, you can also plug the output color of one node into the bump map node^a node that controls how □bumpyn a surface looks^of a texture (which is the same as MM dragging the node onto the bump map channel of the texture), or even control the intensity (or height) of a different bump map based on the output of this node.
While the number of attributes available to connect via the Connection Editor can be a bit overwhelming, the windowns controls are fairly straightforward. Letns take a look at how the Connection Editor works.
Using the Connection Editor
To make a connection, first load the left and right sides of the Connection Editor with the two nodes you wish to connect (or, alternatively, MM drag one node onto another in the Attribute Editor to automatically open and load the Connection Editor). Then click on the output attribute you wish to use and, from the list of attributes with matching data types (not grayed out), choose the input node.
Some data types, like color, have arrows next to them, allowing you to access their component attributes^in the case of color, it would be the red, green, and blue components of the color. Thus, while color (a vector) may not be a match (and is thus grayed out) for the X scale of an object, you can connect the red component of color to the objectns X scale; depending on the direction of this connection, the objectns redness would be controlled by its X scale, or the objectns scale would be controlled by its redness.
The Connection Editor Controls
The controls in the Connection Editorns window are easy to use. The buttons at the top enable you to reload the left or right side of the window (thus changing which node is loaded on each side of the window). By clicking the □from -> ton button, you can change the direction of the input/output of the two nodes (making it □to <- fromn).
The Right and Left Side Filters menus let you display (in the windows below) only those attributes you are interested in^this can be a great way to reduce the clutter of available attributes to a more manageable number.
Under the Options menu, you can change the default behavior of the Connection Editor □which is to make and break connections automatically as you click on the attributes in the left and right windows^to a manual mode. If manual mode is selected, you must press the (now enabled) Make and Break buttons at the bottom of the window to create (or disconnect) the connection between two attributes.
The Clear All button removes all connections, and the Remove button removes the loaded nodes.
Finally, the two arrow keys just below the left and right windows allow you to step through all nodes on an object (for example, the shape to the transform node of a geometric object), saving you a trip back to the Hypergraph to highlight a new node, and then reload it into the Connection Editor. To disconnect two attributes, just click on a connected attribute on one side of the window to unhighlight it.
The possibilities for using the Connection Editor are so many and varied that the best advice is just to open a new project, create some objects and shader networks, and play with different connections, so you can get a feel for the different ways you can control one node via another. This way, when you are faced with what might appear a difficult problem in a □ real worldn situation, you may see that some clever use of the Connection Editor will do the trick nicely.
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