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Synopsis

extendCurve [-caching boolean] [-constructionHistory boolean] [-curveOnSurface boolean] [-distance linear] [-extendMethod int] [-extensionType int] [-inputPoint linear linear linear] [-join boolean] [-name string] [-noChanges boolean] [-nodeState int] [-object boolean] [-pointX linear] [-pointY linear] [-pointZ linear] [-range boolean] [-removeMultipleKnots boolean] [-replaceOriginal boolean] [-start int] object

extendCurve is undoable, queryable, and editable.

This command extends a curve or creates a new curve as an extension

Return value

string[]Object name and node name

In query mode, return type is based on queried flag.

Flags

caching, constructionHistory, curveOnSurface, distance, extendMethod, extensionType, inputPoint, join, name, noChanges, nodeState, object, pointX, pointY, pointZ, range, removeMultipleKnots, replaceOriginal, start
Long name (short name) Argument types Properties
-caching(-cch) boolean createqueryedit
Toggle caching for all attributes so that no recomputation is needed
-distance(-d) linear createqueryedit
The distance to extend Used only for extendMethod is byDistance.
Default: 1
-extendMethod(-em) int createqueryedit
The method with which to extend: 0 - based on distance, 2 - to a 3D point
Default: 0
-extensionType(-et) int createqueryedit
The type of extension: 0 - linear, 1 - circular, 2 - extrapolate
Default: 0
-inputPoint(-ip) linear linear linear createqueryedit
The point to extend to (optional)
-join(-jn) boolean createqueryedit
If true, join the extension to original curve
Default: true
-nodeState(-nds) int createqueryedit

Maya dependency nodes have 6 possible states. The Normal (0), HasNoEffect (1), and Blocking (2) states can be used to alter how the graph is evaluated.

The Waiting-Normal (3), Waiting-HasNoEffect (4), Waiting-Blocking (5) are for internal use only. They temporarily shut off parts of the graph during interaction (e.g., manipulation). The understanding is that once the operation is done, the state will be reset appropriately, e.g. Waiting-Blocking will reset back to Blocking.

The Normal and Blocking cases apply to all nodes, while HasNoEffect is node specific; many nodes do not support this option. Plug-ins store state in the MPxNode::state attribute. Anyone can set it or check this attribute. Additional details about each of these 3 states follow.

State Description
Normal The normal node state. This is the default.
HasNoEffect

The HasNoEffect option (a.k.a. pass-through), is used in cases where there is an operation on an input producing an output of the same data type. Nearly all deformers support this state, as do a few other nodes. As stated earlier, it is not supported by all nodes.

It’s typical to implement support for the HasNoEffect state in the node’s compute method and to perform appropriate operations. Plug-ins can also support HasNoEffect.

The usual implementation of this state is to copy the input directly to the matching output without applying the algorithm in the node. For deformers, applying this state leaves the input geometry undeformed on the output.

Blocking

This is implemented in the depend node base class and applies to all nodes. Blocking is applied during the evaluation phase to connections. An evaluation request to a blocked connection will return as failures, causing the destination plug to retain its current value. Dirty propagation is indirectly affected by this state since blocked connections are never cleaned.

When a node is set to Blocking the behavior is supposed to be the same as if all outgoing connections were broken. As long as nobody requests evaluation of the blocked node directly it won’t evaluate after that. Note that a blocked node will still respond to getAttr requests but a getAttr on a downstream node will not reevaluate the blocked node.

Setting the root transform of a hierarchy to Blocking won’t automatically influence child transforms in the hierarchy. To do this, you’d need to explicitly set all child nodes to the Blocking state.

For example, to set all child transforms to Blocking, you could use the following script.


import maya.cmds as cmds
def blockTree(root):
nodesToBlock = []
for node in {child:1 for child in cmds.listRelatives( root, path=True, allDescendents=True )}.keys():
nodesToBlock += cmds.listConnections(node, source=True, destination=True )
for node in {source:1 for source in nodesToBlock}.keys():
cmds.setAttr( '%s.nodeState' % node, 2 )

Applying this script would continue to draw objects but things would not be animated.


Default: kdnNormal
-pointX(-px) linear createqueryedit
X of the point to extend to
Default: 0
-pointY(-py) linear createqueryedit
Y of the point to extend to
Default: 0
-pointZ(-pz) linear createqueryedit
Z of the point to extend to
Default: 0
-removeMultipleKnots(-rmk) boolean createqueryedit
If true remove multiple knots at join Used only if join is true.
Default: false
-start(-s) int createqueryedit
Which end of the curve to extend. 0 - end, 1 - start, 2 - both
Default: 1
Common flags
-constructionHistory(-ch) boolean create
Turn the construction history on or off.
-curveOnSurface(-cos) boolean create
If possible, create 2D curve as a result.
-name(-n) string create
Sets the name of the newly-created node. If it contains namespace path, the new node will be created under the specified namespace; if the namespace does not exist, it will be created.
-noChanges(-nc) boolean createqueryedit
If set then the operation node will be automatically put into pass-through mode.
-object(-o) boolean create
Create the result, or just the dependency node.
-range(-rn) boolean create
Force a curve range on complete input curve.
-replaceOriginal(-rpo) boolean create
Create "in place" (i.e., replace).

Flag can appear in Create mode of command Flag can appear in Edit mode of command
Flag can appear in Query mode of command Flag can be used more than once in a command.

MEL examples

// to extend the start of a curve with a line of distance 3
extendCurve -em 0 -et 0 -s true -d 3.0;

// to extend the end of a curve to a point
extendCurve -em 2 -s false -ip 1 2 3;