What are they used for, and sometimes they disappear. There is no mention in the document, and I am confused.
Why are there two curves in the curve view?
The two curves you see in the Curves view represent the interpolation between keys for different properties. The Curves view allows you to visualize and edit how values change over time between keys. Sometimes, curves may disappear if the values of consecutive keys are the same, as there is no change to interpolate, which is why the curve cannot be displayed. In such cases, you can use the Graph view to edit the curves between keys with the same value. The Curves view is particularly useful for aligning multiple curves to a specific shape using presets, which can be saved and applied as needed.
Selecting a single Translate (X and Y combined) key will show a single curve -- the X and Y properties use the same curve.
The gray curve appears when you select multiple keys. The curve for the first key you select shows up normally, the rest show up gray. That is done solely so you can better see the curve you care about when you have many selected. You can click or drag another curve in the Curves view to make it colored.
Sorry, I'm not very skilled. It took me a while to figure out what you were talking about. By selecting "Match" you can change multiple values in sync (if the property has multiple values), and by unchecking "Match" you can change a single value individually. Do I understand that right?
I would also like to ask what the "Separate" button next to the "Match" button does. If "Match" is not pressed, then X and Y are set separately. If "Match" is pressed, X and Y are combined. In the above process, there is no difference between the results of the "Separate" button pressed and not pressed.
Do I understand that right?
Yes. Match changes the handles for all selected keys shown in the Curves view when any handle is moved. The Curves view doesn't change key values at all.
For the Изображение удалено из-за отсутствия поддержки HTTPS. | ПоказатьSeparate button, hover or press F1 for the tooltip:
Changing curves will "separate" the handles, so the tangent is broken. This creates a cusp. It makes Spine behave similar to how it did before version 4.0. Enough people needed that, so we added the button, but I don't suggest using it in most cases because it's usually better to avoid cusps.
The tangent is the angle of the handles through the key. Here the curve handles are not separated: Изображение удалено из-за отсутствия поддержки HTTPS. | Показать Изображение удалено из-за отсутствия поддержки HTTPS. | Показать Изображение удалено из-за отсутствия поддержки HTTPS. | Показать
The value of the curve is smooth through the key. Here the curve handles are separated:
The value has a cusp at the key, meaning the value changes abruptly. It can be seen more easily when zoomed in:
Careful not to confuse separating curve handles with separating properties that are normally keyed together (X + Y, scaleX + scaleY, shearX + shearY).
You should view your curves in the Graph to more easily understand how values change over time, especially when starting out. The Curves view is more advanced and is most often used for editing multiple curves at once. Spine used to only have a Curves view. While it's a powerful and unique feature, it gives a very narrow view of the animation. It's easier to understand the curves the Graph view and easier to see how the values change over the whole animation. Also the Graph view can change both key values and curves.