June 03, 2025

PARAM_CONNECTION

This element connects two parameters together: whenever one of the parameters is changed, the other one follows it. It is stronger than two PARAM_LINK elements connecting both parameters because it ensures that both parameters keep the same value.

With two PARAM_LINKs the risk is that they are not equivalent, so they may get into unstable states.

Attributes brief detailed show all inherited

	Name	Description	Default
	id1	Identifier of the first parameterMandatory	empty
	id2	Identifier of the second parameterMandatory	empty
	response_curve	Response curve of the link: this enables the software to compute the value of the second parameter from the value of the first parameter. The inverse function is used to make the computation the other way round	linear
	reverse	Reverse the response curveIf the curve is normalized, the transfer function of the link is:p2=1-f(p1),else it is:p2=max-f(p1)(f being the response curve)	'false'
	normalized	Links the normalized values of the parameters instead of the absolute valuesSet this parameter to true if you want to link the parameters relatively to their ranges, and not as absolute values. 'Normalized' values are set between 0 and 1, 0 corresponding to the minimum and 1 the maximum values of the parameters	'false'
	enabled	Enables or disables the link	'true'
	mode	Chooses the operation mode of the link: in 'absolute' mode the value of the linked parameters are synchronized (according to other settings such as response curve). When diff mode is set, the link incrementally modifies the value of the parameters based on the modified parameter variationsThis parameter is exposed as an integer (0 matching to 'absolute' mode and 1 to 'diff' mode	'absolu...
	constraint	Enables or disables the constraint modewhen in constraint mode, the source parameter changes may trigger a change back so that the connection acts as a constraint. When the constraint mode is off, change messages are never sent back to the source parameter (which may cause parameters not to be in perfect sync). This parameter is always disabled when the connection operates in diff mode. To simplify a bit: not "constrained" target parameter is not locked by the range of the source parameter (see example below).	'true'
Common attributes
	id	Identifier of the elementThe id of an element has to be globally unique. Don't start with a digit for AngelScript compatibility.	empty

	Name	Value type	Default	Description	Comment
	id1	param id	empty	Identifier of the first parameter	Mandatory
	id2	param id	empty	Identifier of the second parameter	Mandatory
	response_curve	response curve	linear	Response curve of the link: this enables the software to compute the value of the second parameter from the value of the first parameter. The inverse function is used to make the computation the other way round
	reverse	boolean	'false'	Reverse the response curve	If the curve is normalized, the transfer function of the link is:p2=1-f(p1),else it is:p2=max-f(p1)(f being the response curve)
	normalized	boolean	'false'	Links the normalized values of the parameters instead of the absolute values	Set this parameter to true if you want to link the parameters relatively to their ranges, and not as absolute values. 'Normalized' values are set between 0 and 1, 0 corresponding to the minimum and 1 the maximum values of the parameters
	enabled	boolean	'true'	Enables or disables the link
	mode	'absolute' or 'diff'	'absolute'	Chooses the operation mode of the link: in 'absolute' mode the value of the linked parameters are synchronized (according to other settings such as response curve). When diff mode is set, the link incrementally modifies the value of the parameters based on the modified parameter variations	This parameter is exposed as an integer (0 matching to 'absolute' mode and 1 to 'diff' mode
	constraint	boolean	'true'	Enables or disables the constraint mode	when in constraint mode, the source parameter changes may trigger a change back so that the connection acts as a constraint. When the constraint mode is off, change messages are never sent back to the source parameter (which may cause parameters not to be in perfect sync). This parameter is always disabled when the connection operates in diff mode. To simplify a bit: not "constrained" target parameter is not locked by the range of the source parameter (see example below).
Common attributes
	id	identifier	empty	Identifier of the element	The id of an element has to be globally unique. Don't start with a digit for AngelScript compatibility.

Examples

A very practical example is when you want to force a value for a parameter (for example when you do not want to have a control for it). In this case just create a parameter with a single possible value and create a connection between this parameter and the one you want to constrain.

In the example below param A is constrained to a fixed parameter (with value 0.3), params B C and D are connected, but B to D is not "constrained", so D is not limited by the range of B.

<PARAM id="A" min="0" max="1" default="0" />
<PARAM id="B" min="0" max="1" default="0" />
<PARAM id="C" min="-2" max="2" default="0" />
<PARAM id="D" min="-2" max="2" default="0" />
<PARAM id="fixed_value" min="0.3" max="0.3" default="0.3" />
<PARAM_CONNECTION id1="A" id2="fixed_value" />
<PARAM_CONNECTION id1="B" id2="C" />
<PARAM_CONNECTION id1="B" id2="D" constraint="false" />
<ROW v_margin="10">
<REPEAT index_list="A;B;C;D">
<COLUMN width="35">
<TEXT value="$index$" />
<LM_SLIDER_A param_id="$index$" />
<PARAM_TEXT_CONTROL param_id="$index$" />
</COLUMN>
</REPEAT>
</ROW>

See more examples in PARAM_LINK, PARAM_MULTI_LINK and Params 101.

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