User manual

Functions defined through States, that modify object's texture coordinates according to

certain State values. Pseudo environment mapping, chrome effect or planar mapping

can be achieved with TexGens [31] (Shaders Glossary)”. The term fixed-functions

stands for “Hard coded rendering algorithms used by GPU on 3D graphics cards. The

real-time 3D card industry started building specialized chipsets (GPU - Graphic

Processor Unit) meant to relieve the CPU from computing most common 3D tasks (flat

shading, gouraud shading, perspective, texture mapping and some blending operations).

Many of those chipsets made the success of SGI workstations, whose technology quickly

trickled down to the game industry via 3D card manufacturers like 3dfx, NVidia and

ATI. Until recently, the main drawback of these inexpensive 3D cards was that

rendering algorithms were limited to hard-coded functions (called Fixed-Functions -

used in the Fixed-Pipeline) implemented by card manufacturers. This constraint is one

of the reasons many 3D games look and feel alike. [31] (Shaders Glossary)” The fixed

function pipeline is a feature introduced with the 1999-2000 Tranform and Lighting

GPUs [24] - so, by using TexGen effects, the target deployment PCs are again limited

to those computers that also have a graphics card of that or a newer generation.

As mentioned previously, most of the calculations related to this specific

projector light simulation, are conducted as part of the projector setup process, within

the init phase of the user site. This process is briefly discussed in the next subsection.

Before continuing, let’s just mention that as a part of the development for a projector

simulation algorithm, an attempt was made to code a pixel shader. It’s development

was abandoned primarily because during testing, a machine with an older GPU, which

could run the TexGen effect, could not run the pixel shader, in spite of it being written

in the lowest version of the HLSL language. Apart from that, it was possible to achieve

a gobo reflection (although not

an accurate one), and to make it

respond to the referential object

movements by using this

experimental shader.

Figure 65. Example of the experimental

pixel shader, rendering a gobo pattern

"DMX Director" - Architecture of a 3D light-programming application, in a multi-user Internet environment