Dissecting Graphics For The Average Gamer (Part 1)

Graphics is the first and only thing we can experience from a game that is still months or years away. They’re there to give us a first lasting impression — whether it’s good or bad. While gameplay is more important, you can only judge graphics and not gameplay from images. Long before the internet, we had only screen shots to judge a game. Even with advances in technology, we’ve only come so far as being able to see the game in motion. Even then, watching a video doesn’t tell us how the game controls, or how well it plays. Demos don’t come till the game is near completion. So while gameplay is still the all important factor to some of us, we have to agonize over screens and videos until we finally get our hands on it. So let’s start talking about graphics!

I know we’re all tired of the lazy half-assed games by 3rd party Wii developers by now; whether it’s the visuals, the gameplay, the controls, or all of the above. Usually, gameplay and controls don’t depend on a system’s power — just time and skills. What about the graphics? We all know by now that the Wii doesn’t come close to the 360 and PS3 when it comes to graphics, but that doesn’t mean we should accept the vomit pukes out by low level 3rd parties when the less powerful Gamecube is capable of this and this. Honestly, with the way some of the games look, calling the Wii: “Two GameCubes scotch taped together” is a compliment! The irony is that I’ve actually seen good efforts getting lambasted by fans and sites as well. Its probably a combination of unreasonable expectations and ignorance. Art can also attribute to the problem, but good art is very subjective. Maybe if we can understand assorted effects used, we can have a better appreciation for technology we’re seeing, and also develop sensible expectations. While this is written for the Wii crowd, the HD systems play a role. I’m going to try to touch on some misconceptions, basic (very basic) techniques, and even tread on the subjective territory of art.

Godzilla Unleashed was one of the first 3rd party games to use environment map bump mapping on the Wii.

Please note that I am not a game developer, and I have ZERO programming knowledge. What I’ve learned over the years come from extensive research online, and talking to people more knowledgeable than myself. If you’re here expecting example codes for certain shaders, you’re out of luck. If you want to know how the GPU works, you’re out of luck. All I know is that 3D graphics are created with polygons and textures, and this article will only going a little bit beyond that. What I’m trying to do is break things into something easy to digest for the average gamer. We’re picking apart some of the smaller details that aren’t so obvious to the player. I can’t go any further than the surface of what you see.

There’s no such thing as 650p, 600p, or 585p

So what makes the 360 and PS3 so advanced? Is it the HD graphics at 720 or 1080p? Actually, quite a few well known 360 and PS3 games don’t even run at 720p. Halo 3 runs at 650p while COD4 runs at 600p. The recent Ninja Gaiden 2 is 585p. That’s only 105 pixels taller than a Wii game. Honestly now, even if NG2 is but a mere 105 pixels taller, it still blows away whatever the Wii has offer graphically. NG2 has a much higher level of geometry; shaders galore; post processing and filters to enhance the overall scene; lots of high resolution textures; and crazy particle effects fill the screen. Remember, we’re only talking about graphical technology here, and I’m well aware that I’ve left out other things. The PS2 and Xbox can upscale to 720p with clever ways around the frame buffer. Maybe someone could find a solution around the Wii’s smaller frame buffer, but at this point, resolution doesn’t matter. At least it doesn’t prove the Wii is anymore powerful than it really is. I can get my DVD player to upscale to 720p, but that doesn’t automatically make it a Hi-Def player. Things like shaders matter more.

Oh, and the title isn’t a joke. There’s really no such thing as 585p, etc. I use it because people can immediately understand I’m talking about the resolution. The reason I use it is because I have no clue what the horizontal pixel resolution for these games are.

Fun with shaders

The Wii can’t do shaders, or at least that’s what the lazy developers would have you believe. It’s true that the Wii can’t do shaders in the sense that you can’t take the code and have it run on the Wii. The Wii and Gamecube uses something called TEV (Texture Environment). It’s just a different way to do the same thing. The problem also lies in that you need to convert the shaders to into something the Wii can understand. Now I’m going to give you a slightly risky example — I say risky because I don’t know whether some computer geek  might point out some flaws and jump all over me over the example. Running shaders on the Wii is like trying to run a program on PC and Mac. Both the PC and Mac can do the same thing, but you need to reprogram it to run on the other machine. If the Wii/GC couldn’t do shaders, you wouldn’t have effects like bloom lighting, bump maps, self-shadows, and among others. Hell, the PS2 and Dreamcast can do these effects. Just because it uses shaders doesn’t mean it has to look mind-blowing. With the Wii, the question should be how many different shaders it can run and how complex can they be.

Pics from PC games will be use throughout this article for easy screenshot purposes.

Let’s get to the basics of what is a shader first. Here’s a quick and easy to understand definition I found online: “A shader defines the final surface properties of an object. For example, a shader can define the color, reflectivity, and translucency of a surface.” If it was as simple as that, I wouldn’t be writing this. What it doesn’t tell you is that shaders can also be either a hardware or software. You can have a video card/console built with X number of shaders, or you can write a shader program and have it run on a machine. Not only that, but shaders themselves are also split into two categories: Vertex Shaders and Pixel Shaders (I’m aware of Geometry Shaders in DX10). Shaders are used to add a wide range of visual effects. I already gave you some examples in the previous paragraph.

The Wii doesn’t have Vertex Shaders in the hardware. Luckily, Vertex Shaders can be emulated through software. I heard the Wii either handles this through the CPU, or some other different hardware feature. Vertex Shaders are used to manipulate vertices, and they also drive the Pixel Shader (more on this later). One of the simplest functions a Vertex Shader does is animation. Every game has animation. What used to be done with CPU are now handled through the Vertex Shaders. The waves you see in water would be a more subtle example of Vertex Shader at work.

The Wii’s TEVs perform some of the same functions as a pixel shader — but with some differences (which I don’t know). First of all, Pixel Shaders control each pixel you see on screen. The easiest way to think of a Pixel Shader is that it colors the pixel. They can handle something as simple as lighting an object, to adding an incredible amount of detail to a polygon. Imagine a modern game where there would be anywhere from 1-2 million pixels each frame is being rendered, colored, and lit all done 60 (or 30) times a second. The amount of control you have over the image is unprecedented, but that doesn’t make Vertex Shaders obsolete. I couldn’t find any idiots guide to how both vertex and Pixel Shaders work together; but from what I can understand, there are effects that require information from the Vertex Shader before the Pixel Shader kicks in. My best guess would something like a knight in shining armor under various lighting conditions. The armor won’t reflect light unless it moves into the light, and the intensity of the reflection differs at various angles of movement. Remember, Vertex Shaders also control animation. The problem with the Wii (and GC) is that the TEVs are fixed function. What this means is that you can’t control it as well of the modern programmable shaders. The programmers are limited by the algorithms implemented in the GPU. Modern GPUs allow the programmer to use the pipelines however they please by writing their own shaders. I believe the Wii’s architecture of the system is closer to the more primitive T&L (Transform and Light) rendering. Factor 5 found ways around this limitation, but as to how they do it is completely beyond me. Just know that the TEVs are fixed function and less flexible compared to Pixel Shaders; but it’s powerful enough that if you’re smart, you won’t be too restricted by it. A perfect example would be HDR running on the Wii. Before Cursed Mountain, nobody thought it was possible for hardware before DX8’s to support HDR. Now the real question is how well can the game run with HDR. HDR is a very intensive effect; even on a high powered video card. You can easily cut your frame rate in half with HDR enabled.

ShadER =/= ShadING

Don’t you just love tech jargon? It’s bad enough that they have so many different terms, they also have multiple names for the same effect; and similar words for two completely different effects. Shader should not be confused with shading. Shading refers to a lighting model (should not be confused with lighting effects) used to shade everything. It’s not unlike the shading that you would use for hand-drawn art work.

We started out with flat shading (see Star Fox on the SNES) where each side of the polygon is a single color, and the adjacent polygon would be a slightly different shade of the same color, and so on and so forth. It was quickly outdated, so we didn’t see too many flat shaded polygons in games.

We quickly graduated to Gouraud shading by the time the PS1 came out. It looks way more realistic compared to flat shading, but is still flawed. Gouraud shading interpolates (estimation) the colors on a polygon. Because it is only an estimate, the results aren’t perfect. You really have to look very hard to notice the flaws. I have to say, though, I’m tired of Gouraud shading.

Now we’ve moved onto Phong shading, or per-pixel lighting. Per-pixel lighting does just as the name implies. No more estimates, no more single colored surfaces, and every single pixel is lit individually. This lighting model is quite possible on the GC and Xbox, but wasn’t widely adapted until this generation. Obviously, it is the most hardware intensive of the 3, but it’s pretty much flawless. The picture below is a good comparison.

This is a superior comparison picture.

The difference between flat and the other 2 are quite clear, but if you can’t see the difference between Phong and Gouraud shading, just look at the edges of the lighting in the Gouraud shading orb and compare it with the Phong shaded orb. Phong shading hides the polygons better with better shading. This is kind of hard to tell in a game environment, but it should give you a clearer understanding of how it works.

Part 2>

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