13 - Curve Editor

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13 - Curve Editor


Animated parameters can also be controlled by a dedicated Curve Editor menu. This menu is opened by clicking on the Animate button in the Menu Bar.

Note: When the Curve Editor is open, you cannot jump between shots on the timeline. The timeline will be locked to the current shot. To move to another shot, close the Curve Editor by clicking on the Animate button; move to another shot and then re-open the Curve Editor again.

The Curve Editor menu has three sections; the Curve List, the Curve Window and the Curve Controls.


The Curve List displays all the animatable parameters in a hierarchical list.

The list can be expanded and collapsed by clicking on the small triangles.

On the right edge of each parameter is a number indicating the total number of key frames that exist for that parameter.

Individual curves can be turned on and off by clicking on the parameter name in the list. If a curve is active and being displayed it is be highlighted in the list. You can activate as many curves as you need.


The main workspace of the Curve Editor is the Curve Window. This is where each animated curve is displayed and where you can manipulate the curve to alter the behavior of the animation.

The horizontal axis of the Curve Window represents time going from left to right. A frame count is shown at the bottom to indicate the number of frames from the beginning of the cut.

The vertical axis of the Curve Window represents the value of a key frame.

The red vertical bar represents the currently displayed frame. You can move this bar by placing your cursor over it, clicking and dragging the frame indicator to a new location. The cursor changes to the Shuttle cursor when placed over the red bar to indicate that you can click and drag the frame indicator.

Zoom, Pan and Framing

You can zoom and pan the Curve Window in the same way as the main Viewport. There are the standard SCRATCH icons in the Curve Editor which allow you to zoom in, zoom out, set the zoom to default and fit the current curve into the Curve Window.

You can also use the same Quick Keys for controlling zoom and pan within the Curve Window.

• Quick Key: Alt

» Scale the time and value range by clicking and dragging

• Quick Key: Home

» Set the shot length and animation range

• Quick Key: Alt + Home

» Set the shot length and curve height

• Quick Key: Spacebar

» Pan around the curve display


Note: The cursor must be placed over the Curve Window for the Quick Keys to affect the curve view.


The Curve Controls allow you to modify the behavior of the animation curves, add and remove key frames, alter the shape of the animation curve and define how the curve will behave beyond the first and last keyframes.

Copy and Paste

Entire animation curves can be copied and then pasted onto other shots. You can select multiple animation curves, copy those curves using the Copy button and then navigate to a different shot and paste the selected curves onto the new shot using the Paste button. The pasted curves are matched by their original name so that like parameters are copied onto one another.

Tip: If a single curve is copied it can be pasted onto any parameter regardless of its name.

Global Mode

Rather than dealing with individual key frames and points, animation curves can be controlled on a less granular level using the Global Mode option. When Global Mode is enabled, a gray X- and Y-Bar appear in the Curve Window.


These bars represent the animation curve’s start- and end-points in time (x-bar) and value (y-bar). Clicking on the end-points of one of the bars allows you to scale the curve quickly. Clicking in the middle of one of the bars allows you to slide the entire curve left and right or up and down to adjust the overall timing or value of the animation, without having to adjust each individual keyframe.

Align on Slot

The align on slot button allows you to shift the curve as a whole to the start of the slot / the in-point of the shot.


The Edit mode allows you to manipulate an individual key frame within the Curve Window. With the Edit mode active, click on any point on the curve and move it to a new location. The Edit mode can also be activated using the Quick Key: E .

• Quick Key: E

» Edit Mode



When the Add mode is active, clicking in the Curve Window adds a new keyframe point to the closest active curve. The cursor changes to a green cross to indicate that you are in Add mode. Add mode remains on until it is deactivated; however you can temporarily activate Add mode by holding down the Quick Key: A while in any other mode. Add mode is deactivated when the Quick Key is released.

• Quick Key: A

» Activate Add Mode



When Delete mode is active, clicking on a keyframe point in the curve window deletes that point from the curve. The cursor changes to a bright red crosshair to indicate that you are in Delete mode. Delete  mode remains on until it is deactivated by switching to another mode. There is no Quick Key for Delete mode.


Select mode allows you to drag a rectangular selection around multiple points.


All points within the rectangle are selected and can be modified as a group. Quick Key: Shift or Cmd.

Note: Multiple points can also be selected by holding down the Quick Key: Control and clicking on each point to be selected. The selected points are highlighted in red.


By default, each keyframe point has two handles which are locked together to maintain a smooth curve through the keyframe. Break mode will allow you to break the two handles apart so that they can be moved independently of one another. This allows you to create instant changes in the slope of an animation curve.

To break the tangency of a keyframe point, select the Break mode, click on the handle you wish to break and move it to a new location. You can also use the Quick Key: B to temporarily activate Break mode.

• Quick Key: B

» Activate Break Mode


The Join mode restores tangency between previously broken handles. This mode functions identically to the Break mode; activate Join mode and then click on a handle to join it with the other handle for that keyframe point. You can use the Quick Key: J to temporarily activate Join mode.

• Quick Key: J

» Activate Join Mode



Keyframe points have two states, Linear or Curved. The default state is Curved but this can be changed using the L/C button.

The L/C button is not a mode like Break or Join, but instead the button represents the current state of the selected point. To switch the state of a point you must first select the point and then toggle the L/C button to the new state. You can also use the Quick Key: I to change the state of any keyframe point.

• Quick Key: I

» Switch Interpolation State


Tip: You can affect the state of multiple points by first selecting multiple points using either the Select mode or the Quick Key: Control , and then clicking on the L/C button. The state of each keyframe point will be toggled to the opposite of its current state, so all points do not have to be in the same state to be affected.


Enable Snap mode to ensure that all keyframe points always snap to the nearest frame in time. With Snap mode disabled, you can place keyframe points between frame boundaries, which can result in unexpected playback results. You can use the Quick Key: S for temporarily activate Snap mode.

Extrapolation Mode

The Start: and End: extrapolation modes control how animation curves behave before the first keyframe and after the last keyframe. Because the first and last keyframes of an animation do not need to fall on the first and last frames of a shot, the settings for these extrapolation scan have an affect on the playback results. There are four possible extrapolation modes: Constant, Linear, Loop and Bounce.


Constant extrapolation means that the value does not change once the end of the animation curve is reached. The value of the first or last keyframe is simply held to the extents of the shot.


Linear extrapolation means the curve maintains a constant slope outside of the animation curve, based on the slope of the first or last keyframe. This slope can be adjusted by changing the handle of the first or last keyframe.


Loop extrapolation duplicates the animation curve over and over. This is useful for creating repeating animation cycles.


Bounce extrapolation is similar to Loop extrapolation, except the curve is not simply duplicated, but is mirrored to create a back-and-forth or bouncing animation.


The Import and Export buttons to the right of the Animation Curve allow you to save and load the numerical animation data. Both buttons will open a file-browser to select a csv-file to open or save. The Export function will save all the selected animated parameters in one single file, using the following format:

#ANIM Guide - Animated Clip\Layers\Layer-1\Canvas Transform\Translate X
#ANIM Guide - Animated Clip\Layerss\Layer-1\Canvas Transform\Translate Y

Each animated parameter has its own section starting with two comment lines which in turn start with a '#' character. The first line of a section-header starts with '#ANIM' and is followed by a reference path to the parameter being animated; clip name\layer name\section\parameter name.This is just for informational purposes. On importing an animation file this line will be ignored. The second line in the section-header contains the start- and end - Extrapolation Modes of the animation as discussed earlier in this chapter. This 2-character code uses an abbreviation of any of the existing Extrapolation Modes: Constant (C),Linear (L), Loop (P), Bounce (B). 'CC' represents both the start and the end of the animation are Constant.

The data-block following the header lines is a comma separated list. The number of columns depends on whether the animation is Linear or Curved. The difference between these modes was explained earlier in this paragraph. If the animation is Linear then there are just two columns; the first representing the frame position and the second the actual parameter value at that position. If the animation is Curved then the six values represent the three control points determining the position and shape of the curve in that position.

On Importing an animation CSV file, SCRATCH will simply check which parameters are selected in the hierarchical list of parameters on the left of the curve. The first parameter selected will be linked to the first section in the animation file, the second parameter to the second section and so on. As mentioned: the first header line in a section with a reference to a parameter is ignored, so you can import data from different clips and types of parameters. If the number of parameters selected differ from the number of sections in the file, SCRATCH will just stop after the last match.


The Curve Editor menu can be resized by clicking on the gripper in the Menu Bar and sliding the cursor up and down on the screen. Once you have the desired size, click again to release the gripper.


There is a quick way to view the animation curve of a particular parameter.

Start by positioning the cursor over the Animate button and clicking down. Do not release the mouse button yet.

Continue to hold down the mouse button and drag away from the Animate button. The cursor changes to the Yellow animate cursor.

Drag the Yellow animate cursor over a menu item for that has had keyframes set. The Yellow cursor changes to green, indicating it has detected the presence of keyframes.

Tip: You can quickly tell how many keyframes a menu item has by reading the K value, now written over the Animate button.

Once the green Animate cursor is active,release the mouse button and the Curve Editor will automatically open with the selected parameter already highlighted and ready for editing.

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Last Modified:Monday, July 01, 2019