I am searching for reference (books, online tutorials) about 2D Special effects, in the style of the ones seen in 2d titles such as Castle Crashers, Zombieville USA.
Both a listage of common solutions + techniques would be great, as I am kind of lost on how to start learning this topic properly.
Can anyone point me in any?
Thanks in advance
Depends on what you mean by '2d effects'.
I'm pretty sure they are both 3d games (not old school 2d sprites). So they are built just like the Unity 2d platform tut.
The artwork is cell shaded. Couple ways to do that.
Worst but easiest way:
1- Unity has a built in cell shader, though I'm not too happy with it. First it can double your draw calls. Every model is turned inside out, rendered a solid color (usually black) and pushed out for line thickness.
The major issue is any polys with hard edges get split (try a cube) and it leaves gaps in the outline. Plus it also only shows outline around the entire object, hard to outline details.
2- You can do this in a modeling program just as easy really. If you use a separate material for the outline color you'll get double draw calls, but you can always hide a little square of black on your texture, then shrink the uv's of the outline model down to nothing and put them on the same sheet, that'll save a draw call and ALOT of performance.
You can also use thick outlines on your texture to outline things like pockets, glasses, hats...
Stuff that wouldn't show with the outline model.
Then still use a cell shade material in Unity, but not an 'outlined one'. That'll give you the flat colors, and with a ramp you can get the 'blocky' highlights. (makes the shading in chunks of color, not smooth real shading so it looks cartoony)
You can get some nice effects in 2D Games by using the built-in Particle Renderer.
Here are some tutorials to get you started:
Some pre-built packages:
It looks like Zombieville actually uses these particle effects in some areas for the explosions and the like, but generally the gibs and such are hand-animated or at least single cels drawn and thrown into Unity's Physics system.
There are several ways of doing 2D in Unity3D, but to achieve a rich set of graphical effects, you’ll need to do them in 3D and use an orthographic camera to make it flat 2D.
The fact that you’re still using the 3D engine gives you access a myriad of graphical effects, including particles, physics and animation blending.
Google for "Graphics Gems" books.