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Synopsis

detachCurve [-caching boolean] [-constructionHistory boolean] [-curveOnSurface boolean] [-keep boolean] [-name string] [-nodeState int] [-object boolean] [-parameter float] [-replaceOriginal boolean] curve

detachCurve is undoable, queryable, and editable.

The detachCurve command detaches a curve into pieces, given a list of parameter values. You can also specify which pieces to keep and which to discard using the "-k" flag. The names of the newly detached curve(s) is returned. If history is on, then the name of the resulting dependency node is also returned.

You can use this command to open a periodic curve at a particular parameter value. You would use this command with only one "-p" flag.

If you are specifying "-k" flags, then you must specify one, none or all "-k" flags. If you are specifying all "-k" flags, there must be one more "-k" flag than "-p" flags.

Return value

string[]Object name and node name

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

Flags

caching, constructionHistory, curveOnSurface, keep, name, nodeState, object, parameter, replaceOriginal
Long name (short name) Argument types Properties
-caching(-cch) boolean createqueryedit
Toggle caching for all attributes so that no recomputation is needed
-keep(-k) boolean createqueryeditmultiuse
Whether or not to keep a detached piece. This multi attribute should be one element larger than the parameter multi attribute.
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
-parameter(-p) float createqueryeditmultiuse
Parameter values to detach at
Default: 0.0
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.
-object(-o) boolean create
Create the result, or just the dependency node.
-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

detachCurve -ch on -p 0.2 -replaceOriginal off curve1;
// Detaches curve1 at parameter value 0.2.  The
// result is two curves and a detachCurve dependency node.
// The "-rpo" flag specifies that the original curve is not to be
// replaced; as a result a new curve is created for each curve piece.
// Note that if "-k" flag is not used, then the default is that
// all pieces are kept.

detachCurve -ch on -replaceOriginal off curve1.ep[1];
// Detaches curve1 at its second edit point.

detachCurve -ch on -replaceOriginal off curve1.u[0.2];
// Detaches curve1 at parameter value 0.2

detachCurve -ch on -p 0.4 -k on -k off -rpo off curve1;
// Detaches curve1 at parameter value 0.4 into two curves.  Because of
// the "-k" flags, two curves are created, but the second one is empty.
// A detachCurve dependency node is also returned.

detachCurve -ch on -p 0.2 -p 0.4 -rpo on curve1;
// Detaches curve1 into three pieces.  Because the "-rpo" flag is on,
// the original curve is replaced with the first piece.  The names
// of all curve pieces are returned.  If curve1 is a result of history,
// then a dependency node is created and its output is connected as
// the input to curve1.  If curve1 is not a result of construction
// history, then a dependency node is not created (even though the
// "-ch" flag is on).

detachCurve -ch on -p 0.2 -p 0.4 circle1;
// Detaches a periodic curve, circle1, at two places.  Before
// the detach, the circle is periodic, with a start parameter of 0.0,
// and an end parameter of 8.0.
// The first parameter, 0.2, is used to move the start point of the curve,
// also called the "seam".  The second parameter, 0.4, is used to perform
// a detach operation.  The result is TWO curves only.  The first curve
// has a parameter range of 0.2 to 0.4.  The second curve has a parameter
// range of 0.4 to 8.2.