Inbetweens

*See also Douga Cook Book.*

Inbetweens make up the majority of drawings in any cut with much motion. Every *dash* on a spacing chart or timesheet must become its own drawing for an animation to be complete. As a douga artist, that's your job. It might sound like a tall order, but there's a logic to creating inbetweens that makes them much less intimidating to work on than it might appear.

Here we have two drawings. The timesheet and spacing chart show there's only one inbetween, which comes at exactly the halfway point between those two keyframes. In other words, it has both even timing and even spacing.

This means that you need a drawing exactly halfway between the two keys. Example 1 below shows how this can go awry. If your drawing fluctuates, then in final playback the form will seem to boil. You don't want this. Instead, go for example 2, smoothly fitting exactly in between the two keyframes. *Again, use whatever tools help you to get the results you need!*

Flipping is extremely useful here. Quickly turn the two keyframes on and off, and move between frames. If you find areas where the line wriggles, center the lines more to fix it.

## Finding Inbetweens

What about when spacing charts have many inbetweens? Where do you start?

You need to follow a process like this. You start with a central inbetween and work your way out from there, referencing each new drawing with the two exactly evenly spaced on either side of it. Doing this keeps the drawings you're working from consistent and makes in-betweens easier to draw.

Sometimes, a spacing chart will have a biased inbetween–one that favors the previous or next key–without having an inbetween in the exact center. Layout artists do this to create a sense of speed or anticipation in their work, but how do you handle it? You need to create a "ghost" inbetween. Spooky.

A ghost inbetween *is* evenly spaced, sitting between the two keys. You draw it fairly roughly since it's not going to be used in the final douga exports. It's just a guide to help you visualize the unevenly spaced keyframe you need to find. I think of it kind of like an inbetween guide you make for yourself.

With the ghost inbetween guide in place, you can find your actual inbetween pretty easily.

## Tracing, Not Copy-Pasting

With a few notable exceptions, the expectation for a douga artist is to trace out each new frame unless they're gousei drawings. Sometimes that can feel pretty frustrating, but it isn't just to make you miserable. I promise! Let's say your job is to animate this ball rolling from frame 1 to frame 2 with one in-between frame. It's just a ball, and so even when it's rolling the shape won't change. It might seem like the simplest thing to do is trace frame 1, then copy- paste it out across all three frames.

The above image looks fine, but very stiff. What happens if we trace it all three times instead? The difference on a simple animation like this is pretty small, but the traced lines don't exactly match up, and this slight variation generally creates appeal. It becomes even more noticeable if you're drawing an organic form like a human.

Of course, It's a balancing act. You want to get your drawings clean enough that nothing looks like it's morphing in an unwanted way without having them feel like copy-pasted carbon copies.

There are a few times when copy-pasting is fine, usually for frames in a cycle separated by several drawings For example, you can reuse the same poses repeatedly in a running animation, you don't have to trace a new one for each cycle. You can also reuse small, rigidly consistent objects between some frames, like pupils.

## Arc Check and Motion Check

If your inbetweens are spaced properly, you're well on your way to creating some solid douga. There's another important check to make, however–this is called the **line check** or the **arc check**. In animation everything follows a set of smoothly connected points. Most of the time the natural motion of a living creature or even a thrown object follows a natural arc.

Like the boxes on the left show, the arcs I'm talking about follow the same points. Corner to corner in this case–but it could also be the tip of a chin moving in a head turn, or the knee of a leg as it's raised on a run cycle. All that really matters is you pick the same point. And follow it through. If your drawings don't follow a smooth curve, it will look like you're skipping frames or the object's teleporting–though it can "accelerate" (become more curved).

If you want, you can draw out the actual arc on a separate layer connecting different keyframes and use that as the basis for your work. I know plenty of artists that do that. You can also sketch in an arc quickly and erase it to check as you progress through a cut.

Since we're working digitally, you can extend this into a "motion check." Export and play the animation as a .mp4 every once in a while to check that the drawings are actually following arcs. A lot of software – including Clip Studio – does a poor job showing you what final rendered frames look like when you scrub through the timeline or use the in-app playback functions on cuts with lots of frames. Exporting to check shows you what it will really look like to your audience.

## Finding the Middle

At this point you might be wondering how, exactly, you're supposed to find the middle of some drawings. It's easy if it's a strand of hair moving at a constant rate, but what if you have a character throwing a fast punch, or blinking as they turn their head and look up–what does it mean to find the "middle" between two other drawings in those situations?

The two important things to consider when finding the middle of a difficult inbetween are:

1. Always follow the arc
2. Use tap wari to help

When you're following an arc, you need to keep the point you're following consistent, and the line must connect the first and last frames of the cut. Even on a cut where you have an object coming forward or backward in space this holds true. It might be helpful to think of everything as being a pendulum. The string on a pendulum is always the same length, and so when the ball at the end swings, it follows a curve through the air. The same thing goes for lots of other things. Human limbs, falling debris, waving grass–almost anything natural. You can *technically* have propelled flying objects like jets or birds move in a straight line, but it's quite common for even these objects to curve in animation. It's just more appealing.

As these examples show, whether it's a punch coming at the camera or a ball swinging on a string, the basic standard of the arc holds true. We can extrapolate this to anything. A hand waving, someone kicking. You name it. Keeping this in mind will help your inbetweens track correctly. You can measure out the distance between the drawings you have following the line of motion to find the exact center.

Using tap wari can help in situations where it's not clear what kind of an arc something should be taking from the keyframes you have at hand. Let's say we have an image of someone raising their leg up, Chun-Li style, then snapping out a quick kick with their foreleg. In the keyframes, you might have something like this:

The basic arcs just follow the natural curves defined by the body based on the length of limbs and position of joints. That's probably not too difficult to understand, but what about the "sub" movements? How do we get the leg from being pressed flat against itself to extend from frame 2 -> frame 3?

We can find movements like this with tap wari. If we were working on paper, this would mean measuring the length of the leg, then rotating that length out to find an arc, something like this:

We can use an arc like this to guide our inbetweens, placing the leg at the proper spacing on the arc based on provided spacing charts. We already have halfway–exactly in the center of the arc–but we can subdivide to find any level of breakdown we might need.

Of course, you might have realized that the leg wouldn't follow an exactly flat arc like this–it would be swung out towards the camera rather than straight up. In that case, we can squash the arc to better match the perspective and guide our inbetweens, but tap wari can still guide the basic arc and help us keep lengths and volumes solid throughout.

If you're working in clip studio, you have access to a particularly powerful tool–the ability to center the canvas between two points with the light table. Simply load the two frames you want to reference into the light table and use the space drawings command, then set it to 50%. It'll snap everything so the drawings are spaced evenly!

You can load the cels you want into the light table, change their color, and slide them around on the canvas all without affecting their actual position, color, or fidelity in the files.

## Finding missing spacing based on timechart

One of the most common problems you'll face working in douga is missing spacing charts. Since spacing charts tell you where your inbetweens need to go, they're really important! Not having spacing charts might seem like it makes it impossible to finish your douga work–and you can certainly ask your PA why they weren't provided–but sometimes you'll have no choice but to reverse-engineer them yourself.

As a basic rule, you're going to favor the first keyframe over the second when deciding on spacing. Let's say you have a cut with three inbetweens where someone is throwing a punch on 3s. Like the example to the right.

We need to think about what inbetween the middle is. In a case like this it's pretty simple. We want to play it safe (remember, in douga, minimal changes!). The middle on the second inbetween. This creates a nice even division. It won't be the most exciting punch, but we know where our middle is and we can create the inbetweens from it.

So how about finding the middle if the layout artist went overboard with inbetweens, putting everything on 1s? In this case you need to use a bit more judgment. If you want to play it safe, you can set the fourth inbetween as the middle. This is going to give you an easy division of inbetweens and keep everything centered. It's the same approach as before, you'll just have more inbetweens to draw.

If you have an even number of inbetweens – say 2 or 6 instead of the 3 and 7 shown here – then you're going to be generating a **ghost inbetween** that's not used in the final animation, with the two finished inbetweens on either side of it, like this example shows.

You might be tempted to try creating uneven spacing on a cut missing spacing charts so the movement is more interesting. I would strongly recommend against doing this unless you have explicit permission or you're in a senior role with lots of experience. It's very easy to create a situation where the inbetweens are badly spaced and create awkward divisions and robbery or jerky movements.