F-Curve Modifiers

Reference

Panel:

Sidebar region ‣ Modifiers

F-Curve modifiers are similar to object modifiers, in that they add non-destructive effects that can be adjusted at any time and layered to create more complex effects.

Modifiers are evaluated from top to bottom. You can change their order by dragging the dots in their top right corner.

Interface

Name

By default, modifiers are named after their function, but this can be changed.

Mute

Click the checkbox in a modifier’s header to disable it.

Delete

Click the cross in a modifier’s header to delete it.

Influence

Lets you blend between the original curve and the modified one.

Restrict Frame Range

• Start/End

  The frame on which the modifier’s effect starts/ends.

  Blend In/Out

  The number of frames, relative the start/end values above, it takes the modifier to fade in/out.

Adding a Modifier

Modifiers can be managed on the Modifiers tab of the Sidebar. Select an F-Curve (in the channel region or by selecting one of its keyframes), then click the Add Modifier dropdown and choose the modifier to add.

Types of Modifiers

Generator Modifier

Creates a polynomial function. These are basic mathematical formulas that represent lines, parabolas, and other more complex curves, depending on the values used.

See also

The Wikipedia Page for more information on polynomials.

Mode

Method used to represent the equation.

• Expanded Polynomial

  Equation in the form \(y = A + Bx^1 + Cx^2 + … + Dx^n\).

  Factorized Polynomial

  Equation in the form \(y = (Ax + B)(Cx + D)\).

Additive

Add the polynomial to the curve rather than replacing it.

Order

The highest power of x for this polynomial.

Coefficient

The constants A, B, C… in the equation.

Built-in Function Modifier

These are additional formulas, each with the same options to control their shape. Consult mathematics reference for more detailed information on each function:

Type

The built-in function to use:

• Sine

• Cosine

• Tangent

• Square Root

• Natural Logarithm

• Normalized Sine: \(sin(x)/x\)

Additive

Add the function to the curve rather than replacing it.

Amplitude

Adjusts the Y scaling.

Phase Multiplier

Adjusts the X scaling.

Phase Offset

Adjusts the X offset.

Value Offset

Adjusts the Y offset.

Envelope Modifier

Lets you reshape the curve. First, you define an envelope, which consists of two horizontal lines that more or less match the curve’s lower and upper bounds. Then, you add control points, where each point can push, squeeze, and stretch the envelope (and the curve along with it) at a certain frame.

Reference

The value which the envelope is centered around.

Min/Max

The offset from the reference value to the envelope’s initial lower/upper bound.

Add Control Point

Adds a control point at the current frame.

Point

• Frame

  The frame of the control point.

  Min/Max

  The offset from the reference value to the envelope’s adjusted lower/upper bound at this frame.

Cycles Modifier

Makes the curve repeat itself.

Note

The Cycles Modifier can only be the first modifier.

Before/After Mode

• No Cycles

  Do not repeat the curve before/after the original.

  Repeat Motion

  Repeats the curve, keeping the values of each copy the same.

  Repeat with Offset

  Repeats the curve, offsetting each copy vertically so that its first keyframe matches the previous last keyframe.

  Repeat Mirrored

  Repeats the curve, flipping every other copy horizontally.

Count

The number of copies to create. A value of 0 means infinite.

Trivially Cyclic Curves

When the Cycle Mode for both ends is set to either Repeat Motion or Repeat with Offset, and no other options of the modifier are changed from their defaults, it defines a simple infinite cycle.

This special case receives some additional support from other areas of Blender:

• Automatic Bézier handle placement is aware of the cycle and adjusts to achieve a smooth transition.

• The Cycle-Aware Keying option can be enabled to take the cycle into account when inserting new keyframes.

Noise Modifier

Modifies the curve with a noise formula. This is useful for adding subtle or extreme randomness to animated movements, like camera shake.

Blend Type

• Replace:

  Adds noise in the range [-0.5, 0.5].

  Add:

  Adds noise in the range [0, 1].

  Subtract:

  Subtracts noise in the range [0, 1].

  Multiply:

  Multiplies by noise in the range [0, 1].

Scale

Changes the horizontal scale of the noise. Higher values make for less dense oscillation.

Strength

Changes the vertical scale of the noise.

Offset

Offsets the noise in time.

Phase

Adjusts the random seed of the noise.

Depth

Adjusts how detailed the noise function is.

Limits Modifier

Limits the curve to specific time and value ranges.

Minimum, Maximum X

Removes the original curve data to the left of the minimum frame and to the right of the maximum, replacing it by Constant extrapolation.

Minimum, Maximum Y

Clamps the curve values, never letting them go below the minimum or above the maximum.

Stepped Interpolation Modifier

Gives the curve a stepped appearance by sampling it every N frames and making it hold its value after each sample. In a sense, this lowers the curve’s frame rate by letting it change its value less frequently, producing choppy movement as a result.

Step Size

The number of frames to hold each step.

Offset

The number of frames to offset the sample points.

Start Frame

The frame where to start applying the effect.

End Frame

The frame where to stop applying the effect.