XSIBlog

Stefano is a shader writer and td at Pumpkin-3D, Paris. He previously served Lumiq Studios, Softimage, Phoenix Tools and Action Synthese. He has been working with mental ray since its first release in Softimage 3D.

The current bump node (formerly known as zbump) became very popular for its simplicity, and for its ability to get procedural textures as inputs.
However, it has some limitations, for instance not supporting texture pre-filtering, and the fact that its spacing is expressed in world coordinates instead of uv coordinates like the old node. This leads [...]

After so many years, Xsi still does not ship any basic trigonometric functions like sine and cosine. Although they are very easy to code for a shader writer, it is, however, possible to dig them out of the existing nodes.
This is an example of how sometimes you can write a phenomenon just to downgrade a [...]

Let’s look at a short technique that will allow you to export any custom function curve or scripting math function to a texturable node to be used in the rendertree.
Let’s get a curve
We start by taking a poly strip, with a 100×1 subdivisions. This will be our “drawing” table. We then make a cluster of [...]

Yes, yet another occlusion technique.

The game is pretending no occlusion nor FG/GI tool is shipping with XSI, and do it with what is left, in particular area lights.
In the end, the result is less accurate than the standard ambient occlusion and FG, but, in some ways, more intuitive and flexible.

The standard occlusion shaders sample the environment sending out a bunch of rays, and return a color based on the percentage of rays hitting some objects. Mathematically speaking, they integrate the hemisphere (or the cone) centered above the normal with the given number of samples. As we know, a higher sampling rate gives better results, [...]