Skeletal versus sprite sheet animations it is a very tender topic for game developers, programmers, animators, etc and in this post we will try to find the advantages and disadvantages for each type of animation. We will start with skeletal animation.

Skeletal animation

Skeletal animation is a technique in computer animation in which a character is represented in two parts: a surface representation used to draw the character (called skin or mesh) and a hierarchical set of interconnected bones (called theskeleton or rig) used to animate (pose and keyframe) the mesh. While this technique is often used to animate humans or more generally for organic modeling, it only serves to make the animation process more intuitive and the same technique can be used to control the deformation of any object — a door, a spoon, a building, or a galaxy. When the animated object is more general than for example a humanoid character the set of bones may not be hierarchical or interconnected, but it just represents a higher level description of the motion of the part of mesh or skin it is influencing. Wikipedia

Image source: http://animadead.sourceforge.net/docs/

On the skeletal animation, the animation is made up of several bones that are connected to each other. When you manipulate the parent bone you also manipulate its child bones. With this transformation on each bone you can create different poses for your skeleton. Defining keyframes for all these transformation you will animate the skeleton.

Sprite sheet animations have been used for a long time in game industry, like the classic game Legend of Zelda: A Link to the Past. The first movie projector was creating by Eadweard Muybridge when he tried to give the illusion of the horse running. Changing images in a quick succession give the impression of movement and this is a sprite sheet animation.

A sprite is a two-dimensionalbitmap that is integrated into a larger scene. Wikipedia

Sprite sheets are used to create large and complex scenes and gives you the opportunity to manipulate each sprite individually. In generally games use hundreds of sprites and they consume a lot of memory and to avoid this thing are used sprite sheets.

Image source: http://stackoverflow.com/questions/14649528/automatically-find-frame-sizes-from-png-sprite-sheet

Skeletal and sprite sheet animations are two methods of animating that have advantages and disadvantages and we will present further.

Advantages:

• skeletal animation uses tools that makes the process of animation easier
• skeletal animation allows you to create dynamic animations because you can manipulate (rotate, translate, scale) all character’s bones at run time
• bone-based animations are easier when you want to make multiple animations for one character
• skeletal animation requires a fewer images and less memory
• skeletal animation allows you to make natural movement with the help of inverse or forward kinematic
• with sprite sheet animation all your data are contained in one texture
• sprite sheet loads quickly
• sprite sheet reduces the amount of draw-calls on your GPU and this means a better performance
• with sprite sheet you can render multiple things in a single draw call

Bibliografy

Hopefully, you’ve got a quick & clear overview on skeletal versus sprite sheet animations. You may find some other useful information on the links below (they also served me as references for this topic).

• https://en.wikipedia.org/wiki/Skeletal_animation
• http://www.cocos2d-x.org/wiki/Skeletal_Animation
• https://gamedevelopment.tutsplus.com/tutorials/an-introduction-to-spritesheet-animation–gamedev-13099
• http://creativejs.com/2012/01/day-11-sprite-sheets/
• https://developer.apple.com/reference/scenekit/scnskinner
• http://stackoverflow.com/questions/3473151/what-are-the-pros-and-cons-of-a-sprite-sheet-compared-to-an-image-sequence
• http://gamedev.stackexchange.com/questions/7069/2d-graphics-why-use-spritesheets
• https://docs.coronalabs.com/guide/media/spriteAnimation/index.html