Sprite Stacking in Godot

Recently, I came across this amazing write-up by Thibaud Goiffon that walked through the process of creating a fake 3D character using a few neat tricks. I had seen something similar to this before in the form of sprite stacking. Sprite stacking is essentially the process of using a series of sprites layered on top of one another with a slight offset to create the illusion of depth. The reason you would use sprite stacking is to allow for many different angles of an object without having to redraw multiple angles.

Not a 3D Model*

This cloak that you see is NOT a 3D model, even though it looks quite 3D. It makes use of sprite stacking in order to appear as though it has a height.

This image shows each of the layers as they are broken out, with the leftmost image being the top of the cloak and the rightmost image being the bottom. In Godot, these sprites are actually flipped and drawn in the reverse order so that they may draw in the proper order. The lower a sprite is on the hierarchy in Godot, the higher priority it has to draw.

Now, as someone who just wrapped up a fairly art-intensive vertical slice, the idea of not having to draw certain objects at many different angles is very intriguing to me. When I first saw this strategy, I was very excited-- but my excitement quickly was quelled when I realized sprite stacking's biggest drawback.

Animating a Sprite Stack

Now, because these sprites are all individual images and not one cohesive sprite, it is very difficult to animate a Sprite Stack in the traditional sense. What I mean is, even though this is pixel art, you cannot animate it like you would animate pixel art. Instead, any and all animation done to a sprite stack has to be done at the top level. Rotations, scales, color tweaks, lerps, all of these work. More complex animation though becomes significantly more difficult. You can't just animate the images and be done, because it's nearly impossible to actually visualize what that animation should look like.

When to Use

Now, this is still a strategy that can dramatically cut down on art time. Particularly, sprite stacking works well on static bodies that will be viewed from different angles. I wish I had known about sprite stacking while I was making Empty Spiral, as I would have been able to save a lot of time when it came to things like the landscape, the wagons, desks, and so many other little props. The biggest benefit of the strategy is that it saves a ton of time that can be spent working on other areas of the game. It gives a degree of freedom in where/how you want to present an object. I'll absolutely be making use of this if I continue my work in 2D Isometric games.

When NOT to Use

If you're making a game that relies on beautiful frame-by-frame animation, sprite stacking is pretty much off the table. In this gif from Empty Spiral, I have the characters doing lots of in-depth animations and switching between attacks and movement. Sprite stacking wouldn't be able to accomplish that.

That said, I don't want to give the impression that you can't use sprite stacking at all with animation. I actually took the little cloak that I made from this experiment and have been fleshing out a little battle system with it. It's still a work in progress, but I'm getting around the limitations of sprite stacking by using some "Rayman hands" to do all of my bigger animations. The head in this experiment is a traditionally drawn sprite as well, just stuck on top of the sprite stack. My hope is by combining sprite stacking, traditional sprites, and interesting particles, I can create a super unique-looking experience without breaking the bank in regards to time and effort.

al Thoughts

Sprite stacking is very cool and I want to explore it more. I briefly played with MagicaVoxel in order to create the model to pull the slices for the stacking, and I think I'd like to try it out more. It's a bit silly to make a 3D model and then split it, but I LOVE how pixel art looks, and pretty much all fantasy voxel art makes me think of Cube World. I am going to push this strategy to the limits and see if I can't make something that is cool and unique.