• Nvidia GeForce 7600 GT Round-up

    Nvidia GeForce 7600 GT Round-up

    Sudeep Naik, Aug 30, 2006 1749 hrs IST

    We received Nvidia 7600 GT samples from Asus, BIG, Forsa, Gigabyte, Leadtek, Palit, Sparkle, and XFX; all of them vying to get into the champion's slot.

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It's been a while since we wanted to write this article. But, for some reason, it got delayed and almost always due to reasons beyond our control. Well, now that I have the opportunity, let me make the most of it.

By now, we are all aware and strongly believe that the 7600 GT is a worthy successor to the 6600 GT, and not just in terms of raw power but it also efficiently handles hardcore AA/AF, HDR, Bloom, and, of course, Shader Model 3.0 support.

I've been doing graphic card reviews for some time now and often come across people who are new to gaming and/or do not necessarily have an understanding of the terminologies used when reviewing the cards. So, before we continue, let's take some time to try and understand the basics about graphic cards and computer gaming.

Computer graphics or CG, as they are commonly known, are all about the number of pixels (resolution), their quality (AA/AF), and the effects associated with them (HDR/Bloom.). Let s start with pixels.

Pixel

A pixel (short for picture element) is one of the many tiny dots that make up the representation of a picture in a computer's memory. Each such element is not really a dot, nor a square, but an abstract sample.

Realistic ambiance and life-like surfaces are created in game using Pixel Shaders.

Pixel Shader

Vertex and pixel (or fragment) shaders are shaders that run on a graphics card, executed once for every vertex or pixel in a specified 3D mesh. They operate in the context of interactively rendering a 3D scene, usually using either the Direct3D or OpenGL API.

A Pixel Shader is a graphics function that calculates effects on a per-pixel basis. It can render, shade, or color each frame. They can also be used to give a high level of surface detail to objects in the frame. But, one has to keep in mind that such a process is expensive (with respect to computing resources and time.)

Typical examples of pixel shading would be facial hair and blemishes, golf ball dimples, and wood that has texture and grain.

These days, developers use Programmable Pixel Shaders (PPS) that give them the ability to create and use a wide variety effects. Most of the effects we see in games today are available on preset palettes that are bundled with these PPS. Thus, developers can exercise abundant creativity to determine and control the amount of lighting, shading, and color for every pixel on each frame that combines together to create a wide array of effects.

That was all about the Pixel; the basic building-block for any form of CG. We'll talk more about how objects take shape in CG.


Vertex

Objects in a 3D scene are typically described using triangles, which in turn are defined by their vertices.

A vertex is the corner of the triangle where two edges meet, and thus every triangle is composed of three vertices. A vertex is a graphics processing function used to add special effects to objects in a 3D environment by performing mathematical operations on the objects' vertex data.

Each vertex is defined using real world (x-y-z) co-ordinates depending on its location in the 3D environment. Vertices may also be defined by colors, textures, and lighting characteristics.

Vertex Shaders

Vertex Shaders change the values of the above mentioned parameters to change the color, texture, or position of the pixels. During the initial days of CG, vertex shading effects were so computationally complex that they could only be processed offline using server farms. But now, the advancement and refinement in technology has integrated these shaders on one square inch of semiconductor.

There are virtually infinite number of effects that developers can create using Pixel and Vertex Shaders. They can use both of them in tandem to create life-like characters and game sequences. As graphic card manufacturers fabricate as many of these as possible, game developers breathe more life and limb (literally!) into their games.

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