Wednesday, January 11, 2012

Computer Graphics: Graphics in Games Week 1

A look at Normal/Bump Mapping and Shaders in games

The topic of Normal/Bump Mapping and Shaders was covered in the first week of classes and it got me thinking, what games have I seen these used in? Well pretty much all of them to be honest. I had never realized that the models that we see are really a much lower polygon count then they appeared to be, using bump mapping to add all that detail into it without causing more triangles to have to be drawn.

As for shaders I now realise all the unique things these algorithms can perform and how it can truly define the look of a game. From bloom, to highlighting, to blurring and distortion, they make a game have a certain style that can separate it from all others or simply add to realism or “awesome” factor.

Bump Mapping – Gears of War and the Unreal Engine

As we were shown in class we had a good look at Batman’s model in Arkham Asylum, without bump mapping and with. The differences were drastic between the two models, going from a really well made, but simple model, to something truly worthy of being batman.

Gears of War 1 Texture pop-in

After seeing this I looked to other games I am sure I had actually seen the non bump mapped model and I couldn’t help but look towards the Unreal 3 Engine. It is actually notorious for what people like to call “pop-in” textures. The game loads all the models as quickly as possible, however sometimes the textures aren’t quite able to load right away. What you see is a character model who is not fully textured and bump mapped or normal mapped properly. This is the closest you can get to seeing how the characters looked like without bump mapping inside the game. But It’s never a pretty sight, since you don’t see a gray scale model but one with really low texture loaded on.

Marcus Fenix (left) before bump mapping applied

After bump mapping applied

This was quite prominent in Gears of War 1, where you saw a character like this and then suddenly “pop-in” the texture out of nowhere. To be honest it was rather funny to see but took me out of the game for a bit. To combat this, Epic Games, in Gears of War 3, while it still did not always load the textures right away, instead of instantly popping in the textures, they smoothly transitioned into them, most likely using interpolation of some sort. It made the pop in less noticeable, but it’s still present. It’s basically built into the engine though so the chances of it disappearing in the Unreal 3 Engine are unlikely. This kind of texture pop in is present in all sorts of Unreal Engine 3 games. If you play the game long enough, you will encounter it once at least.

Shaders - The Legend of Zelda and the Cell shaded look

How the Legend of Zelda was originally envisioned on the Gamecube in 2000

There are many games strive for realism in the look of their game. But every game has a different shader applied that can truly change the look and feel of the game. It can go from shaders that simply modify the color and feel, to very unique and stylized shaders that blend with the models in a fashion that makes it not realistic, but even like a cartoon. The Cell shaded look isn’t brand new, it’s been used since early 2000. The earliest and most popular example of this kind of style I can recall is in the Legend of Zelda: Windwaker. When the Nintendo Gamecube was first announced back in 2000, they showed a Demo of the Legend of Zelda using the power of the game cube.  It showed a realistic Link in a dark setting reminiscent of Ocarina of Time. However in 2001, Windwaker was shown in its Cellshaded form and it was not met with open arms. It was critized for being different, partially because people thought they were promised a realistic looking Link again.

How Windwaker turned out, Cellshaded.

When the game was finally released and the years went by, people began to realize just how affective the style was. It really made the game look unique and feel alive and vibrant. The shader using Cell shaded form made the graphics seem simpler but thanks to Nintendo’s artists and technical prowess, they made a game that could truly stand the test of time. This game still looks great despite the years that have gone by. Other games that have gone for that more “realistic” look have not aged as well as this game has when they were released during this time. By using a shader that made the world look more unique and offering a very vibrant color palette, it gave a world that was a character in itself. If you take a look at even their later released, Twilight Princess in 2006, the game hasn’t aged as well as Wind Waker has when you compare them to newer games. Twilight Princess had to stoop down to the limitations provided by the Wii and Gamecube (since the Gamecube is what it was originally developed on). 

Twilight Princess looks good but is starting to look a little dated due to low resolution textures.

The style of graphics and shaders that Skyward Sword used.

This kind of shader they decided to use again for the Legend of Zelda: Skyward Sword, though not exactly the same. It wasn’t quite cell shaded but used a style that was reminiscent to a living painting. It was slightly cell shaded, slightly realistic, and making it look more like a painting. They are once again trying for a style that does not aim for realism, but for creating a unique looking and beautiful world that can once again stand the test of time graphically. An example of how they really made it look like a painting is the use of draw distance. Objects that are very distant actually appear distorted but in such a way that they look like dabs of paint making up the object. They used a shader to achieve this look and feel, blurring up the object and using an algorithm to generate the look of paint brush dabs.

The painting like effect is most prominent at 1:25 in the video. As the camera moves towards the floating island, you can see it go from a painting like look to more in focus and clear.

There are of course tons of other cell shaded games but these are the ones I really wanted to look into. They show that the use of shaders to go for a less realistic look and more unique one can really make a game last longer visually and overcome hardware limitations.

That’s all for this week about Bump Mapping and Shaders!