Transform, clipping, and lighting

With Transform and Lighting ( T & L or short, English for " transformation and illumination " ) two steps of the graphics pipeline in the 3D computer graphics are referred to. Transform and Lighting as a separate term is mainly used in conjunction with graphics cards that can perform these same steps themselves, thus relieving the main processor.

"Transform " means the transformation of the world coordinates of a vertex in two-dimensional screen coordinates using a transformation matrix. Since both the world coordinates ( object moves in the virtual world) and the transformation matrix ( " camera " moves or changes its zoom ) may change constantly, the transformation for each image must be performed anew.

" Lighting " refers to the calculation of the illumination of an image point, ie, their brightness and color according to the lighting model. In some models such as the simple significant Phong model for this purpose the calculation of the angle between the surface normal and the direction of light source is necessary and significant. This angle must also be calculated for each image, as the position of the object may vary with respect to the light source.

Both operations must be performed for each vertex are simple vector and matrix operations. They are easy to implement in hardware, as no flexibility is required. Since the calculations are also independent of each other, they can be highly parallelized almost arbitrarily. Such an implementation in hardware exceeds the speed of a software implementation of a multiple.

First, the functionality in the graphics chip was implemented in 2000 by Savage S3 Inc. and the GeForce 256 from NVIDIA and from the manufacturers ' Transform and Lighting (T & L) engine " listed, of which Transform and Lighting originates as an independent concept. This feature is supported by all modern chips, since version 7.0, it is an integral part of the DirectX compatibility catalog. For graphics cards without T & L unit steps were carried out either by the program itself or the 3D drivers and calculated in both cases from the CPU.

• Hardware
• Image synthesis