Lighting in Hardware

Real lighting is a must

Anyone familiar with 3D games knows what a difference lighting can make when trying to establish the mood and atmosphere. Quake's dark, shadowy world was conceived only partly due to the limited nature of a 256 color palette. With careful light and shadow placement, id was able to set the atmosphere for the game as well as a precedent for future titles which would take more advantage of subtle lighting (such as System Shock 2 and Nocturne).

Most lighting implementations used today aren't true lights by definition of hardware acceleration. Rather, most are precalculated light maps that increase or decrease attenuation based on how deep the shadows are. In most cases, dynamic lights are an additive pass that removes the shadowed lightmap.

Hardware accelerated lights

GeForce 256 supports up to 8 hardware lights, identical to the number supported by S3's Savage2000. Quite simply, hardware-accelerated lighting allows for much more complex, detailed, and realistic lighting effects than what is possible today. An example of this is in specular vs. diffuse lighting. In broad terms, diffuse lighting assumes light scatters in all directions after hitting an object, and appears soft and uniform. Specularity defines the shininess of an object, and reflects more coherent and packed rays of light, which manifest as a highlight on the object.

Unlit wall

Wall with single light source

A few more lights

Texture maps applied

Completed Scene

Dynamic shadows

Anyone who's played Starsiege Tribes on a GL card can appreciate the usefulness of stencil-buffer shadows. However, few users have actually seen a full dynamically lit and shadowed application, and the gameplay implications (not to mention the raw visual appeal) have yet to be exposed. Most of this is due to the prohibitive performance cost of implementing true lighting - the calculations are numerous and rigorous, but specialized hardware in the form of an integrated lighting engine brings us one step closer to a dynamic 3Dworld.

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