NVIDIA's Shading Rasterizer (NSR) is a second hardware processor that's been integrated in the GeForce2 GTS core and brings with it a revolutionary technology to render real-time per-pixel lighting. The NSR is extremely powerful as it can perform seven pixel operations in a single pass on each of the four pixel pipelines.

NVIDIA Shading Rasterizer (NSR)

The NSR is able to perform the following operations on a per-pixel basis:

• Base Texture
• Bump Mapping
• Diffuse Lighting
• Specular Lighting
• Colored Fog
• Ambient Light
• Alpha Transparency

Gone are the days when lighting calculations are done at the vertices, or corners, of a triangle and interpolated across the entire triangle as the NSR is able to perform calculations at each pixel of a triangle. Think of the NSR as being able to combine the dynamic nature of vertex lighting with the pixel level accuracy of lightmaps.

Per-Pixel Lighting

To ensure added realism with per-pixel lighting, NVIDIA has implemented the physics required to accurately render light sources through the use of highly complex mathematical algorithms.

These images from the Isle of Morg illustrate per-pixel lighting. As the world light source moves across the island, notice the changes and effects it has on the hut, characters, trees and rocks:

Isle of Morg

Scene 1	Scene 2
Scene 3	Scene 4

Per-pixel bump mapping is an exciting feature which is hardware accelerated via the NSR. By encoding surface patterns in texture maps, bump mapping simulates a surface's lighting without requiring additional geometry. By combining per-pixel bump mapping along with lighting techniques, scenes such as these from Evolva can be generated without using additional ploygons or texture maps:

Evolva Rolling Bump Demo (Beta)

Bump Mapping Disabled	Bump Mapping Enabled
Bump Mapping Disabled	Bump Mapping Enabled

NVIDIA continues to work closely with developers by providing development tools that take advantage of per-pixel shading. Computer Artworks was able to implement features of the NSR in Evolva in a few weeks without any additional polygons or textures.

The NSR offers 256 gradiations of reflectivity. Additional texture maps needed to render light in today's games, such as lightmaps, are no longer necessary. This feature will greatly reduce the amount of texture bandwidth needed to achieve realistic effects.

Here's an example of using the NSR to build upon the Isle of Morg's base textures and achieve some interesting effects. Notice the carved out appearance on the stone walls. As light moves by, the shadows change position and give an element of depth.

Isle of Morg

Without DOT3 Bump Mapping	With DOT3 Bump Mapping

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