## FCurveKey.Constraint

### Description

Sets or returns a Boolean value indicating whether or not the specified fcurve key constraint is set. The siFCurveKeyConstraint values are of type Long (see siFCurveKeyConstraint for a list of possible values).
Warning: Getting and setting this property in Python is not supported. To set a specific constraint in Python, use the "Set" prefix with method syntax: 'fcrvkey.SetConstraint( c.siLockConstraint, true )'. This is demonstrated in the Python example below. To get a specific constraint, use the Python-compliant method FCurveKey.GetConstraint2 instead.

### C# Syntax

    // get accessor
    Boolean FCurveKey.get_Constraint( siFCurveKeyConstraint in_eConstraint );
    // set accessor
    FCurveKey.set_Constraint( siFCurveKeyConstraint in_eConstraint, Boolean out_pVal );

### Parameters

Parameter | Type | Description
--- | --- | ---
Constraint | siFCurveKeyConstraint | The type of fcurve key constraint to set or return. You can add these values together to specify several constraints at once. For example, use siParameterConstraint + siSameLengthTangentConstraint to lock all parameters and force left and right tangent lengths to be the same.

### Examples

#### 1. JScript Example

    /*
            This example illustrates how to create an fcurve with keys and then how to set a
            constraint on one of the keys.
    */
    // ---------------------------------------------------------------------------------
    // Functions and Setup
    // ---------------------------------------------------------------------------------
    function GetConsList(fckey,setchk)
    {
            var dicConstraintTypes = new ActiveXObject( "Scripting.Dictionary" );
            dicConstraintTypes.Add( "LockParameter",                siParameterConstraint );
            dicConstraintTypes.Add( "LeftRightParameter",           siLeftRightValuesConstraint );
            dicConstraintTypes.Add( "G1Continuous",                 siG1ContinuousConstraint );
            dicConstraintTypes.Add( "LeftRightTangentDirection",    siLeftRightTangentDirectionConstraint );
            dicConstraintTypes.Add( "LeftRightTangentLength",       siLeftRightTangentLengthConstraint );
            dicConstraintTypes.Add( "LockAll",                      siLockConstraint );
            dicConstraintTypes.Add( "HorizontalTangent",            siHorizontalTangentConstraint );
            dicConstraintTypes.Add( "ExtremumHorizontalTangent",    siExtremumHorizontalTangentConstraint );
            dicConstraintTypes.Add( "AdjustedTangent",              siAdjustedTangentConstraint );
            dicConstraintTypes.Add( "ZeroLengthTangent",            siZeroLengthTangentConstraint );
            dicConstraintTypes.Add( "SameLengthTangent",            siSameLengthTangentConstraint );
            dicConstraintTypes.Add( "NeighborTangent",                      siNeighborTangentConstraint );
            dicConstraintTypes.Add( "MirrorTangent",                        siMirrorTangentConstraint );
            dicConstraintTypes.Add( "AutoPlateauTangent",           siAutoPlateauTangentConstraint );
            var strlist = "";
            var vbKeys = dicConstraintTypes.Keys();         // the Dictionary.Keys method returns a safearray
            var jsKeys = vbKeys.toArray();                  // that you can convert with the toArray() method
            for ( var k=0; k<jsKeys.length; k++ ) {
                    if ( setchk == fckey.Constraint( dicConstraintTypes.Item(jsKeys[k]) ) ) {
                            strlist += jsKeys[k] + " ";
                    }
            }
            return strlist;
    }
    // ---------------------------------------------------------------------------------
    // Create new scene
    // ---------------------------------------------------------------------------------
    NewScene( null, false );
    // Create a null
    var n = Application.ActiveSceneRoot.AddNull()
    // Add a custompvar to the null
    var cpset = n.AddProperty( "Custom_parameter_list", false, "CustomPSet" );
    // Add a double parameter to cpset
    var x = cpset.AddParameter3( "X", siDouble, 0, -100, 100, 1 );
    // Create a fcurve on posx
    var fc = x.AddFCurve2( new Array(1,0.5), siStandardFCurve );
    var fckey = fc.Keys(0);
    // ---------------------------------------------------------------------------------
    // Set the siLockConstraint ( time, value & tangents are locked )
    // ---------------------------------------------------------------------------------
    // Set the Constraint property
    fckey.Constraint( siLockConstraint ) = 1;
    if ( fckey.Constraint(siLockConstraint) ) {
            Application.LogMessage( "fckey(" + fckey.Index + ") lock all constraints: true" );
    } else {
            Application.LogMessage( "fckey(" + fckey.Index + ") lock all constraints: false" );
    }
    Application.LogMessage( "fckey(" + fckey.Index + ") constraints set: " + GetConsList(fckey,true) );
    Application.LogMessage( "fckey(" + fckey.Index + ") constraints NOT set: " + GetConsList(fckey,false) );
    // If you try and change the key value when the lock constraint is on it raises
    // an 'Access Denied' error.
    try {
            fckey.Value = 5;
    } catch(e) {
            if ( e.number ) {
                    Application.LogMessage( "fckey(" + fckey.Index + ") set value failed: " + e.description );
            }
    }
    // ---------------------------------------------------------------------------------
    // Expected results::
    // ---------------------------------------------------------------------------------
    //INFO : fckey(0) lock all constraints: true
    //INFO : fckey(0) constraints set: LockParameter LeftRightParameter G1Continuous LeftRightTangentDirection LeftRightTangentLength LockAll AutoPlateauTangent
    //INFO : fckey(0) constraints NOT set: HorizontalTangent ExtremumHorizontalTangent AdjustedTangent ZeroLengthTangent SameLengthTangent NeighborTangent MirrorTangent
    //INFO : 2009 - fckey(0) set value failed: Access denied

#### 2. VBScript Example

    '
    ' This example illustrates how to create an fcurve with keys and then how to set a constraint
    ' on one of the keys.
    '
    ' ---------------------------------------------------------------------------------
    ' Functions and Setup
    ' ---------------------------------------------------------------------------------
    function GetConsList(fckey,setchk)
            set dicConstraintTypes = CreateObject( "Scripting.Dictionary" )
            dicConstraintTypes.Add "LockParameter",                 siParameterConstraint
            dicConstraintTypes.Add "LeftRightParameter",            siLeftRightValuesConstraint
            dicConstraintTypes.Add "G1Continuous",                  siG1ContinuousConstraint
            dicConstraintTypes.Add "LeftRightTangentDirection",     siLeftRightTangentDirectionConstraint
            dicConstraintTypes.Add "LeftRightTangentLength",        siLeftRightTangentLengthConstraint
            dicConstraintTypes.Add "LockAll",                       siLockConstraint
            dicConstraintTypes.Add "HorizontalTangent",             siHorizontalTangentConstraint
            dicConstraintTypes.Add "ExtremumHorizontalTangent",     siExtremumHorizontalTangentConstraint
            dicConstraintTypes.Add "AdjustedTangent",               siAdjustedTangentConstraint
            dicConstraintTypes.Add "ZeroLengthTangent",             siZeroLengthTangentConstraint
            dicConstraintTypes.Add "SameLengthTangent",             siSameLengthTangentConstraint
            dicConstraintTypes.Add "NeighborTangent",               siNeighborTangentConstraint
            dicConstraintTypes.Add "MirrorTangent",                 siMirrorTangentConstraint
            dicConstraintTypes.Add "AutoPlateauTangent",    siAutoPlateauTangentConstraint
            strlist = ""
            dkeys = dicConstraintTypes.Keys()
            for each k in dkeys
                    if setchk = fckey.Constraint(dicConstraintTypes.Item(k)) then
                            strlist = strlist & k + " "
                    end if
            next
            GetConsList = strlist
    end function
    ' ---------------------------------------------------------------------------------
    ' Create new scene
    ' ---------------------------------------------------------------------------------
    NewScene , 0
    ' Create a null
    set n = Application.ActiveSceneRoot.AddNull()
    ' Add a custompset to the null
    set cpset = n.AddProperty( "Custom_parameter_list", , "CustomPSet" )
    ' Add a double parameter to cpset
    set x = cpset.AddParameter3( "X", siDouble, 0, -100, 100, 1 )
    ' Create a fcurve on posx
    set fc = x.AddFCurve2( array(1,0.5), siStandardFCurve )
    set fckey = fc.Keys(0)
    ' ---------------------------------------------------------------------------------
    ' Set the siLockConstraint ( time, value & tangents are locked )
    ' ---------------------------------------------------------------------------------
    ' Set the Constraint property
    fckey.Constraint( siLockConstraint ) = 1
    if fckey.Constraint( siLockConstraint ) then
            Application.LogMessage "fckey(" & fckey.Index & ") lock all constraints: true"
    else
            Application.LogMessage "fckey(" & fckey.Index & ") lock all constraints: false"
    end if
    Application.LogMessage "fckey(" & fckey.Index & ") constraints set: " & GetConsList(fckey,true)
    Application.LogMessage "fckey(" & fckey.Index & ") constraints NOT set: " & GetConsList(fckey,false)
    ' If you try and change the key value when the lock constraint is on it raises
    ' an 'Access Denied' error.
    on error resume next
    fckey.Value = 5
    if Err.Number then
            Application.LogMessage "fckey(" & fckey.Index & ") set value failed: " & Err.Description
    end if
    on error goto 0
    ' ---------------------------------------------------------------------------------
    ' Expected results::
    ' ---------------------------------------------------------------------------------
    'INFO : fckey(0) lock all constraints: true
    'INFO : fckey(0) constraints set: LockParameter LeftRightParameter G1Continuous LeftRightTangentDirection LeftRightTangentLength LockAll AutoPlateauTangent
    'INFO : fckey(0) constraints NOT set: HorizontalTangent ExtremumHorizontalTangent AdjustedTangent ZeroLengthTangent SameLengthTangent NeighborTangent MirrorTangent
    'INFO : 2009 - fckey(0) set value failed: Access denied

#### 3. Python Example

    #
    # This example illustrates how to create an fcurve with keys and then how to set a constraint
    # on one of the keys.
    #
    # ---------------------------------------------------------------------------------
    # Functions and Setup
    # ---------------------------------------------------------------------------------
    # Get the Softimage constants from win32com.client and error handling from pythoncom
    from win32com.client import constants as c
    from pythoncom import com_error as e
    constrainttypes = [ \
            (c.siParameterConstraint,                       "LockParameter"),\
            (c.siLeftRightValuesConstraint,         "LeftRightParameter"),\
            (c.siG1ContinuousConstraint,                    "G1Continuous"),\
            (c.siLeftRightTangentDirectionConstraint,       "LeftRightTangentDirection"),\
            (c.siLeftRightTangentLengthConstraint,          "LeftRightTangentLength"),\
            (c.siLockConstraint,                            "LockAll"),\
            (c.siHorizontalTangentConstraint,               "HorizontalTangent"),\
            (c.siExtremumHorizontalTangentConstraint,       "ExtremumHorizontalTangent"),\
            (c.siAdjustedTangentConstraint,                 "AdjustedTangent"),\
            (c.siZeroLengthTangentConstraint,               "ZeroLengthTangent"),\
            (c.siSameLengthTangentConstraint,               "SameLengthTangent"),\
            (c.siNeighborTangentConstraint,                 "NeighborTangent"),\
            (c.siMirrorTangentConstraint,                   "MirrorTangent"),\
            (c.siAutoPlateauTangentConstraint,              "AutoPlateauTangent") ]
    def GetConsList(fckey,setchk):
            strlist = ""
            for ( c, strc ) in constrainttypes :
                    if fckey.Constraint(c) == setchk:
                            strlist += strc
                            strlist += " "
            return strlist
    # ---------------------------------------------------------------------------------
    # Create new scene
    # ---------------------------------------------------------------------------------
    Application.NewScene("", 0)
    # Create a null
    null = Application.GetPrim("Null", "", "", "")
    # Add a custompset to the null
    cpset = null.AddProperty("Custom_parameter_list",0,"CustomPSet")
    # Add a double parameter to cpset
    x = cpset.AddParameter3( "X", c.siDouble, 0, -100, 100, 1 )
    # Create a fcurve on posx
    fc = x.AddFCurve2( [ 1, 0.5 ], c.siStandardFCurve )
    fckey = fc.Keys(0)
    # ---------------------------------------------------------------------------------
    # Set the siLockConstraint ( time, value & tangents are locked )
    # ---------------------------------------------------------------------------------
    # Notice how you have to use 'SetConstraint' for the Constraint property when setting
    fckey.SetConstraint(c.siLockConstraint,1)
    if fckey.Constraint(c.siLockConstraint) :
            Application.LogMessage( 'fckey(%d) lock all constraints: true' % (fckey.Index) )
    else :
            Application.LogMessage( 'fckey(%d) lock all constraints: false' % (fckey.Index) )
    Application.LogMessage( 'fckey(%d) constraints set: %s' % (fckey.Index,GetConsList(fckey,1)))
    Application.LogMessage( 'fckey(%d) constraints NOT set: %s' % (fckey.Index,GetConsList(fckey,0)))
    # If you try and change the key value when the lock constraint is on it raises
    # an 'Access Denied' error.
    try:
            fckey.Value = 5
    except e, (hr, msg, exc, arg):
            if exc and exc[2]: msg = exc[2]
            Application.LogMessage( 'fckey(%d) set value failed: %s' % (fckey.Index,msg))
    # ---------------------------------------------------------------------------------
    # Expected results::
    # ---------------------------------------------------------------------------------
    #INFO : fckey(0) lock all constraints: true
    #INFO : fckey(0) constraints set: LockParameter LeftRightParameter G1Continuous LeftRightTangentDirection LeftRightTangentLength LockAll AutoPlateauTangent
    #INFO : fckey(0) constraints NOT set: HorizontalTangent ExtremumHorizontalTangent AdjustedTangent ZeroLengthTangent SameLengthTangent NeighborTangent MirrorTangent
    #INFO : 2009 - fckey(0) set value failed: Access denied

### See Also

FCurveKey.GetConstraint2