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Old 07-23-2007   #1
Kwanza
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GTA IV Graphics/Engine Analysis

GTA IV Graphics Engine Analysis
I've made this post for, quite possibly, the more nerdy and technical among the GTA fans here. The point of it, is to examine sets of screen shots from trailers, and scans for errors, technicalities, improvements, and things they're doing very VERY right. Yes, I'm aware that footage we've seen is beta. Yes, I'm aware that most problems could/can be fixed. But, it's still neat looking for the things they've done very right so far, and I will congratulate them for that, as they are doing very excellent, graphics/engine wise. The game looks very good so far, good job R*!

Now what can you expect from this? Well, I'll be analyzing small details in the screen shots, and try and explain what's going on as much as possible. I'm not a 3D programmer, nor an expert on this. I play a lot of games, and pay attention to small graphical details, stuff that the average gamer doesn't even notice as their driving along in game. Feel free to correct me on any errors, or discuss anything. Keep arguing out of this thread please, or things like "We already knew that.", as I'm sure there IS stuff here that you've already noticed. Think of it as a summary as well. Onto the juicy analysis!


http://www.gtagaming.com/images/gtaiv/trailer2/38.jpg
This image from the trailer has raised a lot of speculation, as proof to R* using the DMM engine. Of course, as some people may have noticed, it's clearly not. Why?

http://img365.imageshack.us/img365/9665/gtarat1om1.jpg
In the circled area, you can see the texture for the glass penetration overlapping with the frame of the car. It's typical graphics stuff, you can see similar things in many games. They haven't done anything wrong here, you'll barely notice it in game. But, this is confirmation that they are NOT using the engine, DMM, at least not on the glass. Two other things to notice in there, is the cops don't have shadows underneath them. I can understand this being taken out, as having tons of pedestrians roaming the street, all with dynamic shadows, would have a heavy impact on the frame rate in-game. Another is, the wood on the mid-left of the image, are kind of strewed all over the place. They seem to be placed at random, or moved there only using their own physics. Perhaps a cop car crashed through there, but this seems to be an example of a small portion of destructible environment, and dynamic physics on props within the map.

http://www.gtagaming.com/images/gtaiv/trailer2/46.jpg
Now, in this image, there isn't a lot to take note of. But, on the gas pump, on the chrome part, the reflections are really weird. I'm praying R* doesn't go back to their old reflection method, of just having a static image for a sunset move along a reflective surface depending on the angle. Yes, they did that in SA, I'll look for a thread on it later. The reflection on the gas pumps however, appears to be of some trees. I'm not sure what kind of gas station is placed right next to a bunch of trees, nor a gas station that only has ONE pump, but those trees are close. Let's hope it's just an error in the reflections.

On the subject of reflections though,
http://www.gtagaming.com/images/gtaiv/trailer2/41.jpg
in that image, the reflections on the car are perfect. Everything is correctly in it's place. Perhaps R* is just not bothering with proper reflections on things such as the gas pump, as it would be a thing you rarely take note of.

http://www.gtagaming.com/images/gtaiv/trailer2/37.jpg
No real complaints in this picture, just admiring a few things. First, the bullet holes look really good. Compare them to some bullet decals in some of your favorite shooters, up close. You'll see what I mean. Second, the treads on the tires.. simply gorgeous. They look like honest-to-god, real tires. The lighting, the texture, spot-on. The towers in the background, beautiful as well. The textures and bump-maps give them life, as well as the reflectiveness of them. Only thing bothering me, is the texture is the same on all of them. Not all dirt and rust goes on the same on everything. :p Really good shot, overall.

http://files.gtanet.com/images/3481_gta_iv_trailer.jpg
I'm positive that the fact that the wheels of the cop car are clipping with the ground, has been mentioned, so I won't bother. They messed up a bit there, as the car didn't even shift it's weight as it went onto the sidewalk. I'm sure it'll be fixed, the car models aren't complete yet. - UPDATE: In this image, the cops tires actually aren't clipping with the ground. It's a mixture of a weird angle, and the fact that, where the cop is turned onto the sidewalk, it's actually an entrance. The sidewalk is lowered down, as if an entrance to a parking lot. So, one less error on Rockstar's part.

But, what's good about this shot? Again, the tires. Absolutely perfect. You can see what I mean a bit better in this shot. They're just 100% ace, even better than most racing games (which is embarrassing for them). The road looks great, and even small details like, the tire of the car is compressed at bit on the road, as it has weight. Another important thing here is, the car is NOT floating above the road in any way. In most modern-day engines, the characters, models, props, vehicles, all float above the ground, even sometimes ever-so-slightly. Most of you have seen this before, and know what I mean by it. In GTA? They're touching, interacting with the ground. They have weight, and this is going to affect how realistic the entire city feels.

http://www.gtagaming.com/images/gtaiv/trailer2/47.jpg
Few more things going on here. Of course, there's the glitch of the man floating above the anchor. I'm sure that's been spotted before. Take note of the garbage and debris on the ground here. It's not a flat texture that floats around randomly, like in past GTA games. This makes the streets look authentically littered upon, and adds depth to the world. I'm not sure if they'll have proper physics as you drive/run by the garbage, we'll have to wait and see. The pedestrians walking in the background, again you can see his weight. You can see he's touching the world, as he is part of it. This is a pretty big achievement for R*. The view is fantastic, and the texture quality in the background is pretty high for such an immerse scene. Not sure how they pulled it off, though even in the trailer you can see a drop in frame rate at this scene.

http://i19.tinypic.com/5xdbsi9.jpg
In this scan, you can see Niko crouching behind a car, with two dead gangsters in the background. Again, you can see his weight, and interaction with the environment, as he is apart of it. Now, the bodies. This is a real achievement in physics engines. First off, they aren't posing in a typical ragdoll "Foot-behind-the-head, ballerina" pose. They look like dead, limp bodies. Natural fall poses. Also, another important note, they aren't clipping with the ground. Most modern-day ragdolls, their arms will fall into the ground, or their legs. They look pretty legit overall. The lighting in this scene is perfect, and Niko demonstrates self-shadowing, which is still pretty new to the game industry. His head is casting a shadow onto his back/shoulders, which makes him fit into the scene a lot more nicely.


That's all for now. I'll be examining more screen shots as they are released, and expect a better, more full-scale analysis from me when a new trailer is released. Until then, discuss, comment, and suggest fixes for this article.

- Lee (afterfl0w)

Last edited by Kwanza; 07-25-2007 at 01:21 AM..
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