Use the curve~ object to produce a signal that goes from an initial to target value over a specified time. It is similar to the line~ object, it produces non-linear ramps using a piecewise approximation of an exponential function.
Examples
Curved ramps used as control signals for frequency and amplitude
Discussion
This object uses the Max time format syntax; envelope times can be either single valued fixed or tempo-relative. The curve~ object produces non-linear ramps using a piecewise approximation of an exponential function. You specify the parameter to this exponential function in the curve~ object's right inlet. Values from 0 to 1 produce an "exponential" curve when increasing in value and values from -1 to 0 produce a "logarithmic" curve. The closer to 0 the curve parameter is, the closer the curve is to a straight line, and the farther away the parameter is from 0, the steeper the curve. curve~ can also accept a list of up to two or three arguments (the previous curve parameter is used if there are two arguments), or a list with two or more value, time, parameter triples. The curve~ is limited to 42 such triples in a single list. The object's approximation of the exponential becomes better when the vector size is smaller, but the object also becomes more computationally expensive.
Arguments
initial-value [number]
Optional
The first argument sets an initial value for the signal output. The default value for the parameter is 0.
curve-parameter [number]
Optional
The second argument sets the initial curve parameter. The default value for the curve parameter is 0.
Attributes
maxpoints [int]
Specify the maximum number of user defined points allowed in the curve. The default is 129 points.
Common Box Attributes
Messages
int
Arguments
target-value
[int]
In left inlet: The number is the target value, to be arrived at in the time specified by the number in the middle inlet. If no time has been specified since the last target value, the time is considered to be 0 and the output signal jumps immediately to the target value (ints are converted to floats).
float
Arguments
target-value
[float]
In left inlet: The number is the target value, to be arrived at in the time specified by the number in the middle inlet. If no time has been specified since the last target value, the time is considered to be 0 and the output signal jumps immediately to the target value.
In left inlet: The first number specifies a target value; the second number specifies an amount of time, in milliseconds, to arrive at that value; and the optional third number specifies a curve parameter, for which values from 0 to 1 produce an exponential curve and values from -1 to 0 produce a logarithmic curve. The closer to 0 the curve parameter is, the more the curve resembles a straight line, and the farther away the parameter is from 0, the more the curve resembles a step. In the specified amount of time, curve~ generates an exponential ramp signal from the currently stored value to the target value.
In middle inlet: A list may be used to specify time in one of the Max time formats.
In left inlet: The first number specifies a target value; the second number specifies an amount of time, in milliseconds, to arrive at that value; and the optional third number specifies a curve parameter, for which values from 0 to 1 produce an exponential curve and values from -1 to 0 produce a logarithmic curve. The closer to 0 the curve parameter is, the more the curve resembles a straight line, and the farther away the parameter is from 0, the more the curve resembles a step. In the specified amount of time, curve~ generates an exponential ramp signal from the currently stored value to the target value.
In middle inlet: A list may be used to specify time in one of the Max time formats.
factor
Arguments
nonlinear-factor
[float]
The word factor followed by a float will adjust the non-linear shaping parameters of curve~.
pause
In left inlet: Pauses the internal exponential ramp but does not change the target value nor clear pending target-time-parameter triples. curve~ will continue outputting whatever value was its current value when the pause message was received, until either it receives a resume message or until a new ramp is input.
resume
In left inlet: Resumes the internal exponential ramp and subsequent pending target-time pairs if the curve~ object was paused as a result of the pause message.
stop
In left inlet: Stops the internal exponential ramp and clears pending target-time parameter triples. curve~ will continue outputting whatever value was its current value when the stop message was received, resetting its target value to that value.
Output
bang
Out right outlet: When curve~ has finished generating all of its ramps, bang is sent out.
signal
Out left outlet: The current target value, or an exponential curve moving toward the target value according to the most recently received target value, transition time, and curve parameter.
