SIGGRAPH 2012 Technical Papers Preview

SIGGRAPH just uploaded the Technical Papers Preview Trailer for 2012. Fluid effect seems the primary topic this year, with totally 8 related papers accepted.

All technical papers:

http://s2012.siggraph.org/attendees/technical-papers

Art of Rendering

A Great Article about GI and comparison among renderers: 

http://www.fxguide.com/featured/the-art-of-rendering/

[RenderMan] Ri Filters

The following is a snippet of code I wrote to test with Ri Filters. The goal is to simply replace any polygonal geometry with RiSphere, then replace any RiSphere with RiCone before the final RIB being passed to the renderer.

First filter plugin:

RifPlugin *RifPluginManufacture(int argc, char **argv)
{  
    return new myRifPlugin();
}
myRifPlugin::myRifPlugin()
{
    myRifFilter.PointsGeneralPolygonsV = pointsGeneralPolygons_to_RiSphere;
    myRifFilter.Filtering = RifFilter::k_Continue;
}
RifFilter &myRifPlugin::GetFilter()
{  
    return myRifFilter;
}

The second filter plugin is almost like the first one, except the registered callback needs to be changed to "myRifFilter.SphereV = riSphere_to_RiCone". With riSphere_to_RiCone defined as follow:

RtVoid myRifPlugin2::riSphere_to_RiCone(RtFloat radius, RtFloat zmin, 
      RtFloat zmax, RtFloat tmax, RtInt, RtToken[], RtPointer[])
{
    RiCone(0.5, 0.5, 360, RI_NULL);
}

Now it's about to render! If rendering with RMS (RenderMan Studio), it's better to check the Full Paths box in the Render Settings. Besides, set all the necessary Ri Filters (just new 2 Rif in this case ) and provide the paths toward 2 Plugins. Within command prompt,

render -r rman xxx.ma [ render the image with RMS]

render -r rib xxx.ma [export the rib after replacing]

If using RPS (RenderMan Pro Server),

prman -rif myRifPlugin -rif myRifPlugin2 xxx.rib [ render the image with PRMan]

catrib -o filtered.rib -rif myRifPlugin -rif myRifPlugin2 xxx.rib [export the rib after replacing]
Right, if using RPS, you need to generate rib first for filter processing. RMS accepts .ma for filtering but RPS only accepts .rib.

If everything runs correctly, all the polygonal geometries (lets say if we create 3 cubes in Maya) should be rendered as 3 cones in the final image. Cheers!!

The Walking Dead S1&S2: Behind the Scene

The Walking Dead S2 just ended. It's one of my favorite US TV series. Initially I thought it's another version of "Dawn of the Dead" or "Resident Evil", another cliche or something. I was wrong. It completely held my attention from the very first episode. Well...of course it couldn't avoid having some cliche material from those plot we've been familiar with. It still have lots of fresh stuff that the preceding didn't explore that much. The story is more on the humanity side. The visual effects, compositing, and zombie makeup are best of all. AND it's also the first zombie-related TV series. Here embedded 2 Vimeo videos from Stargate Studios which handled the visual effects of it. They really did an amazing job!!

The following link are 2 articles from fxguide, giving a quick look over what's going on behind the scene. Worthing reading!! 
http://www.fxguide.com/featured/stargate_studios_walking_the_dead/
http://www.fxguide.com/featured/the-walking-dead-season-2-walk-harder/ 

[Maya] Custom Shape Nodes

I've worked on building system with custom shape nodes in Maya for a while and truly learnt a lot from it.

Maya indeed provides great proxies for developers to make custom shape nodes with different level of complexity. Using MPxSurfaceShape (or MPxComponentShape), combined with  MPxSurfaceShapeUI & MPxGeometryIterator &MPxData, you can implement a "very complicated" shape node in Maya. This node can have developer-defined data structure. The data itself can be an attribute which is able to connect to other nodes. You can also define the shape node's behavior under Maya's tools, such as move, rotate, scale, even deformer (lattice, cluster, etc)!!!! And with context command, interacting with custom shape nodes with defined context tool outside becomes possible. This work flow and mechanism is really awesome!!! well... just a flash into my mind, can it support dynamic stuff? Or should I do it outside and write the result back to the shape nodes? hmmm I will figure that out. 

Because they are just proxies, which means you have to do the coding for the actual content. Maya gives you lots of flexibility, but meanwhile, you also have to follow its rules. It would take a while to realize those provided virtual functions of each proxy, like when they will be called and how to make Maya recognize your shape node (Oh Ya, this is the main point!! You have to make Maya recognize your shape node and be able to interact with it!!)

Looking at my system growing bigger and bigger is excited. The custom shape nodes and context tools are almost done. It's time for the official greeting to Renderman API!! Hello Renderman!! :)