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kiwillama

2D Animation

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I'm wondering how games like "Insanely Twisted Shadow Planet" do their 2d animations? link to trailer I find it rather hard to swallow that they would use something like sprite sheets. Especially since they world seems to move dynamically. Could they be using some advanced vector representation? All the art seems very crisp. Anyways I'd simply like some opinions and maybe links to some articles =)

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The same way 3d games are made ? It's just a bunch of polygons, so for animations you can either have precomputed position keyframes between which you interpolate ingame, or have some sort of skeletal system which you can apply dynamic forces to (like ragdoll for 3d models) and which affect the vertex positions, or combination of both.

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Original post by kiwillama
That doesn't answer my question =(

I want to know how games "like Insanely Twisted Shadow Planet" are done for platforms such as the xbox360...

That's because you're not aware that it is possible to render Flash animation on Xbox 360, etc. Google "Scaleform."

In any case, you can achieve a given visual result in several different ways. You can choose to render polygons as snoutmate mentioned, you can render out sprites in advance, you can build a vector engine based on b-splines and inside-out tests to fill continuous regions...

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Scaleform looks cool but it also looks like its only available for big budgets. Is there anything else like it for the Indies?

Not just big budgets, but only established game studios. I contacted Scaleform when I worked at an established interactive studio that had won awards for Flash design and they said they were not yet in a position to deal with us unless we had a license for, say, Unreal Engine 3.0. They have to focus on a core demographic first, since they're a startup (launched in '05, I think).

Scaleform is sort of built on gameswf, which is GPL. Take a look at that.

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Thanks for the info Oluseyi. I hope to see more technologies like scalefrom in the future.

I was hoping someone knew of a framework/game which does something like this for its animations: http://http.developer.nvidia.com/GPUGems3/gpugems3_ch25.html

So are most 2d games still done using sprite sheets? for example how do most games do 2d character animations?

sprite sheets seem so... primitive to me

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Original post by kiwillama
So are most 2d games still done using sprite sheets? for example how do most games do 2d character animations?

sprite sheets seem so... primitive to me

That's because you believe that polygonal 3D is more "advanced" than sprite-based 2D, which is an erroneous notion: they're both just techniques, they're not mutually exclusive (see billboarding) and neither one is superior to the other. Before our computers got fast enough to perform the mathematical computations necessary for real-time lit and textured 3D, we actually hybridized them by computing position, orientation and scale mathematically and then blitting sprite fragments in place. See DOOM and Duke Nukem 3D.

All these techniques are just tools, and one curious phenomenon is that some fall out of favor due to hardware advancements but then come back for a different application - though I hope bank switching (a mid-90s technique for turning 64KB video memory banks into a simulated linear address space, which sometimes required switching mid-pixel in 24-bit color modes) stays away for good, or at least remains relegated to hardware!

2D character animation is achieved in different ways depending on the effect desired. For instance, Bionic Commando: Rearmed uses full 3D graphics with an orthographic projection to generate a strictly 2D result. Viewtiful Joe does use 3D graphics, but it also uses sprites - or flat textured polygons, as you can see in the backgrounds when the camera tilts a bit. Castle Crashers uses sprites throughout, drawn in the smooth vector style of Flash (because it was actually drawn in Flash). Odin Sphere, on the other hand, appears to use a blend of sprites and 2D skeletal animation.

There's nothing primitive about sprite sheets. In fact, you're going to find it virtually impossible to create animation that is more fluid than a talented cel/sprite sequence. You can read this essay by Chris Evans (formerly of Crytek, currently of ILM) on the relative advantages of 2D and 3D for more - and to see why sprite sheets remain an essential tool.

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That's because you believe that polygonal 3D is more "advanced" than sprite-based 2D, which is an erroneous notion...


Id like to peacefully disagree with you on that one. Unless I am mistaken polygon based animation is much more dynamic than a predrawn sprite sheet.

Imagine a character running and shooting at the same time. From what I know this needs to be drawn out with sprite sheets where as vector based models can blend run and shoot animations together.

Also, what about dynamic interactions with the world? lets say you wanted a 2d jelly fish to have a soft body deformation when a fish hits it? I can't Imagine how this would be done using sprite sheets without faking the effect.

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...For instance, Bionic Commando: Rearmed uses full 3D graphics with an orthographic projection to generate a strictly 2D result. Viewtiful Joe does use 3D graphics, but it also uses sprites - or flat textured polygons, as you can see in the backgrounds when the camera tilts a bit. Castle Crashers uses sprites throughout, drawn in the smooth vector style of Flash (because it was actually drawn in Flash). Odin Sphere, on the other hand, appears to use a blend of sprites and 2D skeletal animation.


Thanks! I'd really like to know more on those games =)
Are there any papers out there about advanced 2d rendering techniques?

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But making a perfect round ball remains impossible with triangles. On sprites you can draw the most complex shapes for the same (low) price. Which is why modern 3D games still use sprites for stuff like cables, particles, fire, decals, wires, chains, etc. Though image sprites also have the disadvantage of being pixelated when using a low-res image or standing close enough.

Vector-based graphics like Flash fix that "zooming problem". They are not the same as 3D/polygons or pre-drawn sprite images. They build their visuals from scalable components (line, bezier, circle, polygon, etc.) and calculate those realtime. So instead of drawing a circle at a certain level of detail, it calculates the circle each time again. This way you get the perfect circle/curve for any zoom level. Which gives very smooth&sharp graphics. But at a price of course. Doing all that math on the fly is more expensive than simply using a texture that already has all the information. But probably that's not that much of a problem on the systems nowadays. Maybe I'm wrong, but I'd say its (maybe in combination with 3D) the best way to do 2D games for now. Although I still love pixelated NES graphics as well :)

My 2 cents,
Rick

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Original post by kiwillama
Id like to peacefully disagree with you on that one. Unless I am mistaken polygon based animation is much more dynamic than a predrawn sprite sheet.

Imagine a character running and shooting at the same time. From what I know this needs to be drawn out with sprite sheets where as vector based models can blend run and shoot animations together.

A sprite based system can use separate sprites for the upper body and legs, so that the running and running-and-shooting animations reuse half the same frames.

Quote:
Also, what about dynamic interactions with the world? lets say you wanted a 2d jelly fish to have a soft body deformation when a fish hits it? I can't Imagine how this would be done using sprite sheets without faking the effect.

All effects are faked. The only question is how.

Quote:
Are there any papers out there about advanced 2d rendering techniques?

There are, though I can't point you to any right off the top of my head. My recommendation would be to peruse the archives of the various ACM publications and SIGGRAPH in particular.

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Original post by spek
Maybe I'm wrong, but I'd say its (maybe in combination with 3D) the best way to do 2D games for now.

I'm not sure I'd say it's the best. I think it comes down to what your preference is, what your objective is. As nice and useful as vector graphics are, they can be limited at depicting complex objects with nuanced shading - you'll notice that Flash work tends to have rather simplistic, flat coloring except when raster (bitmap) images are imported as symbols, which brings us back to where we started.

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