Your Guide to Using SLATE

Action Clips Overview

“Action Clip” or just “clip”, is a general-purpose term for everything that can be added within Cutscene Tracks. Each track type though as seen later on has a different set of Action Clip types that are possible to be added to it, but some things maybe found in common amongst different Action Clip types which are best to be described here first before moving on with the rest of the documentation. For this documentation section we use Play Audio Clip, which is an Action Clip that wraps up and plays back an audio clip.



(1) Timing

The controls here reflect the start time (IN) and the end time (OUT) of the clip, as well as its length (shown in the middle) which is the result of the IN and OUT of course. While you can adjust these from the inspector, it is far easier to simply do so in the editor by clicking & dragging the edges of the clip.


(2) Blend In/Out

Most clips have Blend In and Blend Out properties. Generally speaking, these properties control how the clip blends into whatever is that it is doing, as well as how it blends out at doing nothing at all and having no effect. These properties can both be controlled within the clip’s inspector panel, however it is once again far easier to simply do so within the editor by clicking & dragging the edges of the clip while holding down the CTRL key!


Some clips are cross-blendable which means that they can cross-blend with other clips in the same track. Animation clips are an example of such clips. In the case of cross-blendable clips, the Blend In and Out properties are automatically adjusted depending on how much the clips overlap with one another.AnimationLooping

TIP: Sometimes you may not want to blend out of a clip’s effect, but rather clamp¬†the effect of the clip. This can be done by simply setting the Blend Out property to zero.

(3) Parameters

All clips have at least some parameters to set. In Slate most clip parameters are Animatable Parameters, which allows the clip to have embedded animation over its length similar to how it’s done in various animation software like Softimage, Maya, Cinema4D, or After Effects to name a few. For the Audio clip example, the volume, pitch, and stereo pan at which the audio is playing can be animated. Similarly, the target position of where the character is looking at in the “Look At” clip, can be animated within the clip directly, which is of course much more intuitive than having another actor group with a game object animated only for that purpose.

Animatable Parameters can be quickly recognized by their special Tiber color GUI in the inspector. By default, all Animatable Parameters start as “not-animated” but can be made “animated” simply by keyframing them once. Creating keyframes can be done in many ways, but the most obvious one is with the “key” button right next to the parameter. If the parameter is already animated and auto-key is enabled in the preferences (it is by default), then simply changing the parameter will keyframe it to the current time. All Animatable Parameters that have at least one keyframe added to them will also show a mini editor when they are folded out, within which you can edit the keyframes and animation curves of that parameter.

  • A keyframed parameter will show in red color.
  • The “key” button will show in red color if the parameter has a keyframe at the current time, and clicking it will remove the keyframe at that time instead of adding one.
  • The left and right arrow buttons will move the current time to the previous and next keyframe of the parameter.
  • Through the “gear” button of the parameter you can remove all keyframes, set the pre and post wrap mode of the curves (clamp, loop, ping-pong), as well as disable the animation of the parameter temporarily.

Finally, as far as the inspector shown at the start of this section, you will notice that the Play Audio Clip inspector also has three buttons at the bottom Match Previous Loop, Match Length, and Match Next Loop. Every action clip that wraps up some other measurable clip like in this example an audio clip, shows these control which you can use to make the length of the Action Clip match a specific amount of loops of the sub-clip (the audio clip in this example) that it wraps up.


All clips that have keyframed parameters will also show a mini DopeSheet over their clip in the editor which is very useful to manipulate the keys directly in the Slate editor without the need to fall-back to the parameter fold-out in the inspector panel. In both cases however (inspector panel DopeSheet and clip DopeSheet), the controls are exactly the same. See the Shortcuts Cheatsheet Section.


Curve Editor

Animatable Parameters curves can also completely be edited in-line with the Slate timeline instead of only through the clip’s fold-out inspector! To open the inline editor, simply click on the “curve” button found next to the track and select the clip you want to edit its parameters. Once again in both cases (inspector panel curve editor and in-line curve editor), the controls are exactly the same. See the Shortcuts Cheatsheet Section.


More Clip-Related Controls


When scaling a clip, the default behaviour is to not affect the keyframes at all. However:

  • If you hold down the Shift key, keyframes will be moved/shifted while you adjust the start of the clip.
  • If you hold down the Control key on the other hand, keyframes will be retimed to keep the same relative spacing within the clip range as shown in the example below.



When working with multiple clips it’s good to remember that holding down the Shift key while moving a clip will also shift all clips in the same track after the clip that is being currently moved, which is a very quick way to move a lot of clips to create some time-space.



In the clip’s right-click context menu an option to “Fit” the clip exists. This option will make the clip fit between neighbor clips.



Clips can also be split at a specific time through their right-click context menu. If the clip has any keyframes when it is split, new keyframes will be created at the split point to retain the original keyframed animation as intact as possible.




Rect selecting multiple clips even between different tracks is also possible as well. When you have multiple clips selected, apart from being able to move them all together, or deleting them, you can also scale them altogether by clicking & dragging the edges of the rect selection.


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