Transform, clipping, and lighting

Computers make 3D pictures for games.

First, they change a 3D scene into a flat view. This is called a transform. Next, they use clipping. Clipping means they only draw what you see.

Then, they add lighting. This changes the colors of surfaces. It makes things look real.

In the past, the main computer chip did this work. Now, special parts do it much faster. This lets games have big, complex worlds. It makes games look very good.

Computers use a special set of steps to make 3D games. These steps are called T&L. T&L stands for transform, clipping, and lighting.

First, the computer does a transform. This turns a 3D scene into a flat view. Next, it uses clipping. Clipping means the computer only draws the parts you can see. Finally, it uses lighting. Lighting changes the colors of surfaces to make them look real.

In the past, the main computer chip did all this work. This is called software T&L. But 3D games were getting very complex. The main chips could not keep up. In 1999, Nvidia released the GeForce 256. This card used hardware T&L. This means it had special parts to do the work. It was much faster than using software. It even had a cache to help. A cache stores data so the chip does not work twice on the same thing.

At first, not all games used these special parts. Some companies thought fast main chips were better. But soon, most games needed T&L to work well. By the end of 2001, almost all graphics chips had it.

Computers use special tools to build 3D worlds. These tools are called transform, clipping, and lighting. People often call this T&L. Transformation is a very important first step. It turns a 3D scene into a flat, 2D view. This is how you see a world on a screen.

Next, the computer must use clipping. Clipping means the computer only draws what you can see. It ignores parts of the scene that are not in the picture. After that, the computer uses lighting. Lighting changes the colors of different surfaces. This happens based on lighting information. It makes the digital world look much more real.

For a long time, the main computer chip did this work. This was called software T&L. In 1994, some consoles used special parts to help. The Sega Saturn and Sony PlayStation used these parts. The Nintendo 64 used one in 1996. In 1999, Nvidia released the GeForce 256. This was a big change for home computers. It brought hardware T&L to the consumer market.

Hardware T&L is much faster than software T&L. The GeForce 256 used a cache to work even faster. A cache helps by not processing the same vertex twice. In 1999, the Aladdin VII motherboard also had this hardware. S3 Graphics released the Savage 2000 in late 1999 too. However, it did not have the right drivers for Direct3D 7.0. This meant it could not use hardware T&L for all games.

At first, some companies did not think T&L was useful. They thought a fast main CPU was better. The 3dfx Voodoo5 5500 did not have a T&L unit. It could still match the speed of the GeForce 256. But by the end of 2001, things changed. Almost all graphics chips had hardware T&L by then. This allowed games to have much more complex scenes.

In the world of computer graphics, creating a realistic 3D environment requires several complex mathematical steps. These processes are known as transform, clipping, and lighting, or T&L for short. Transformation is the process of turning a three-dimensional scene into a two-dimensional view. This allows a user to see a 3D world on a flat computer screen. Clipping is the next step in the sequence. It ensures the computer only draws the parts of the scene that will actually appear in the final picture. Finally, lighting alters the colors of various surfaces based on specific lighting information. Together, these three tasks allow computers to render detailed and believable digital worlds.

To understand how T&L works, we must look at how the computer handles data. Transformation takes the coordinates of a 3D scene and projects them onto a 2D plane. This allows the viewer to perceive depth and perspective. Clipping then acts as a filter for the scene. It removes any objects or parts of objects that fall outside the camera's view. This prevents the computer from wasting power on things the player cannot see. Lighting is the final part of this core process. It calculates how light hits different surfaces to change their color. This creates shadows and highlights that make objects look solid rather than flat.

Historically, these tasks were handled through software T&L. This means the main CPU, or central processing unit, performed all the math. While powerful CPUs could do this, they eventually struggled to keep up. As 3D games became more complex, the demand for detailed lighting and geometry grew very fast. By 1999, the industry began moving toward hardware T&L. This moved the heavy math away from the CPU and onto specialized graphics hardware. This shift allowed for much more complex scenes and much faster rendering speeds for players.

Specialized hardware for T&L appeared in different ways across different devices. In the mid-1990s, arcade systems and home consoles began using coprocessors. For example, the Sega Genesis used the Virtua Processor in 1994. The Sony PlayStation used the GTE, and the Nintendo 64 used the RSP in 1996. These were not traditional hardware T&L units, but they acted like software T&L running on a separate chip. It was not until 2001 that consoles like the GameCube and Xbox featured more traditional hardware T&L. This evolution shows how developers moved the workload to specialized parts to gain speed.

The consumer PC market saw a massive change in late 1999. Nvidia released the GeForce 256, which introduced hardware T&L to PC graphics cards. This card was unique because it included a cache. This cache helped the card avoid processing the same vertex twice in certain situations. This made vertex processing even faster than standard hardware. Other companies also tried to enter this market. S3 Graphics released the Savage 2000 in late 1999, but it lacked working Direct3D 7.0 drivers. This meant it could not effectively use the hardware T&L features that gamers wanted.

At the time, there was a big debate about whether hardware T&L was actually useful. Some companies, like 3dfx, believed a fast CPU could simply do the work instead. The 3dfx Voodoo5 5500 did not have a T&L unit, yet it could still match the performance of the GeForce 256. Similarly, the STMicroelectronics PowerVR Kyro II rivaled expensive cards in 2001 without hardware T&L. However, as game developers began optimizing their games specifically for hardware T&L, these advantages disappeared. The Kyro II eventually lost its edge and is not supported by most modern games today.

By the year 2000, the industry was standardizing around this technology. While early critics doubted its value, hardware T&L soon became essential. By the end of 2001, all discrete graphics chips featured hardware T&L. This standardization allowed for the next major leap in graphics: DirectX 8.0. This new era introduced fully programmable vertex and pixel shaders. Even though the technology changed, older hardware remained useful for a long time. For instance, the GeForce 256 was still supported in games like Star Wars: Empire at War as late as 2006.