an annoyed writer said:
Z-fighting, a problem with object placement on the Z-axis(that's the vertical one) is more prevalent than ever due to the most effective way of managing the problem has been removed.
Actually, the "Z" refers to the Z axis in the projection used to rasterize the image, which is an axis that extends directly out from the player's camera view. It starts at camera location and extends into the distance directly down the middle of the view.
To avoid having to sort polygons prior to rendering a frame, modern games* use what's called a "Z-buffer." The Z-buffer is basically an image with the same resolution as the frame being rendered. At every pixel, rather than storing a colour value, it stores the value of the closest object (according to this "Z" axis) to the camera that has been drawn at that pixel.
When a polygon is being drawn on the frame, the renderer tests every pixel which the polygon is being drawn on. If the polygon's distance from the camera (according to this "Z" axis) is closer at a given pixel than the value currently at that pixel in the Z-buffer, the polygon gets drawn at that pixel, and the Z-buffer's value at that pixel is overwritten with the new Z distance. Otherwise, the polygon doesn't get drawn into that pixel.
The problem with this method is that the Z buffer doesn't have infinitely good precision. If two surfaces are very nearly in the same position as each other, the computer can't tell which surface to draw on top. Because of how computations are ultimately rounded in some way or another to the low precision of the Z buffer, and because the inputs to these computations will change as the camera moves, the computer will sometimes make differing decisions as to which polygon (and even which parts of which polygons) should be drawn on top, causing flickering from frame to frame.
The two main solutions are, of course, more precise Z-buffers and making sure that parallel and near-parallel polygons aren't hanging out on top of each other.
*Games like Doom and Marathon use a simple sort of what are called "portal engines" which make sorting MUCH easier than in modern engines, and so they do not use Z-buffers. Simply drawing things back-to-front ("painter's algorithm") was cheap, and totally the way to go. Actually, back then, the concept of Z-buffer was seen as inelegant, lazy, and very much brute force-ish. But as the modern 3d engine was born, sorting algorithms became the terrifying [http://nothings.org/gamedev/thief_rendering.html] pinnacle of silly horrifyingness.
//======================
ANYWAY.
So far, custom games have been mostly valuable for standard gametypes on forged maps, due to the custom gametypes situation still being dealt with. Hopefully people will figure out some awesome things; I know some people are trying to fake invasion-like stuff out of dominion and extraction, for instance.
By the way, Relay seems surprisingly good from the little playing I've had on it.
Halo 4's driving physics so far seem extremely well-suited to Race, and despite the lack of checkpoints I've had some fun on some "race" maps in fake "race" gametypes. I really hope they can add a race gametype in. :/
