These are highlights of major changes since the
5.5 release of houdini.
Compiler Changes
Function Additions/Modifications
Area Sampling and Global Illumination
All functions which perform ray-tracing (trace(),
refractlight(), reflectlight(), fastshadow(), filtershadow(),
hittest()) can take optional parameters to cause area
sampling to be done.
The new irradiance
function can be used to compute irradiance in mantra.
Irradiance is computed by sampling stochastically over the
hemisphere and computing the incoming illumination from the
other geometry in the scene.
The new occlusion
function can be used to compute ambient occlusion in mantra.
Like the irradiance function, the hemisphere is
sampled. But rather than computing the illumination from the
rest of the scene, only occlusion testing is performed. This
can be much faster than irradiance computation.
The new photonmap
function can be used to evaluate a photon texture. Photon
maps can be generated using mantra or i3dconvert. The
photonmap function is available in all VEX contexts
(not only shading).
There is a new VEX context to construct shaders for photon shading. This context is
invoked when mantra is generating photon maps.