Spine provides integrated modules for 14 major engines including GameMaker Studio, Cocos2Dx, LOVE, MonoGame, Unity, XNA, Flash, HTML 5, libgdx, Corona, and more. Generic runtime libraries are also available for C, C++, Objective C, C#, JavaScript, Lua and ActionScript 3. Dozens of third party libraries support additional targets.
Spine Essential includes nearly all features, except IK, weights, and meshes. Spine Professional is expensive, though it does give all future updates for life (Spine is updated very often).
No-nonsense workflow allows you to create your artwork in programs much better suited for the task like Illustrator and Inkscape for example, while Spine itself focuses only on the important task of skeletal animation.
Spine received resounding support from Kickstarter backers, beating its pledge goal by over 5 times. A second successful Kickstarter added meshes and other important features.
This is a very useful feature because you can make a walk animation that you can simply change the animation weight to see the character start running, because it will increase the scale of the movement of the bones in the animation. This will increase the hand and the leg swing as you increase the animation weight and the character, making it appear as though it is running.
Yes, there will be a free upgrade to Spriter Pro 2 which will have this feature, but it will be years until that program is read as mentioned on the official site. The issue being that they do not have a way to program this in their current exported runtime. So, for not both Dragon Bones, Spine, and Blender, are the best options it seems for 3D mesh support which really adds something to game animations.
Vertices can't be animated, so you can't have ANY organic feel (like... lungs breathing).
Parent bone can't be animated without affecting the children. This is especially impeding for organic feel, again.
No option to show & unshow assets (or it is hidden), like for switching weapon on your character for exemple.
Unlike other 2D tools, a full animation spline for the entire timeline is displayed, just like other professional 3D animation tools. This allows much more precise and accurate editing of ease in/ease out operations.
Among various game engine supported, Unity is the most up to date runtime including the most recent features, many samples, integrating well in the Unity editor.
Cheaper than Toon Boom and Adobe Products. People often complain about the price hike, but the pro version does go on sale, and even the full priced version is less than other insdurty standards on the market.
It beats Adobe Flash and Toon Boom at vector based animation. It has more features for 2D vector animations with it's integration with 3D mesh and bone rigs. Smart bone rigs create better animtions with less distortions then Toon Boom, and there are no bone rig animation options with Adobe Flash.
In most cases you'll have to export and edit sprite sheets. This will consume memory. Also, FBX file support is limited and not all features will run in Unity. Aside from Unity, there is no support for runtimes for video game engines. Also, many animation features such as vector integrated features will not export to Unity. Spriter, Spine, and Dragon Bones would be better options.
Self-import images, self-upload body part layers, customizable facial features and expressions; You can also make custom motions and save to ‘my library’.