Lighting
Programmers need to choose the type and color of lighting in their 3D world, as where it is coming from. This dictates what the object will look like, where the shadows fall, and what portions of an object you can see and which are hidden. The process or performing all these calculations is quite complicated. Even with only one light source, every surface reflects and refracts light differently. Add several light sources to the equation, and this will ge com,plicated fast.
Programmers make use of a technique called ray-tracing to calculate the path light waves will travel from any given light source out to surfaces of varying texture and type. There are entire books out there written about the subject of ray tracing, most of which would knock you out with boredom in two minutes flat. Luckily, there are a variety of programs out there for 3D developers that do all of this calculation fo them.
Perspective
Adding perspective to an image is an absolute necessity to create a full 3D world. The simplicity of it is basically making items that are far away appear smaller, and this process goes on and on until one reaches the vanishing point, at which anything is too small to see. 3D graphics use this method of adding perspective. In order to do this, a video processor makes use of what is called the z-buffer, named after the Z-axis which gives depth to the normal x-y axis plain. With the z-buffer, each polygon making up an object is assigned a number, which would correspond to its position on a z-axis. Lower numbers are right up at the screen, and higher numbers are very far away nearest the vanishing point. By comparing the x- and y- values with the z- value, the processor can decide whether one object is in front of another, thereby deciding which polygons to hide and which to render. In the real world, this is a given – if an item is in front of another one, you can’t see the one behind it. To computers, there’s a lot of work to do to figure this out.
Anti-Aliasing
Anti-aliasing is a technique designed to fool your eyes. The problem its trying to solve is demonstrates easily. Digital video systems, your PC included, are best at rendering simply lines. When it comes to curves, it is really using a series of little lines to make up the curve. Without anti-aliasing, the curve might look more like a staircase then a real curve. Anti-aliasing is simply the practice of blurring up edges slightly by altering the colors of the pixels on the edge slightly. The effect is to fool the eye into thinking its a real curve.
You can see anti-aliasing in action in the image to the right. This is a zoomed up image of the edge of a chipset. You can clearly see how the top edge is blurred up using similar colors. Each pixel around the edge blends the edge into the background. The effect, when zoomed out, is that the edge looks smooth and there are no “jaggies”, which are all too familar with 3D graphics.
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