Tuesday, May 13, 2008

some Renderman

I can translate this to VEX later.
seems i need to know vi or something similar for efficient text editing.
at the moment i have Context which seems ok and has custom features for editing RIB files but not sure about VEX.

from "Renderman for beginners"
1.4 "How a renderer works"

3D scene description
object to world to camera transformation
clipping, culling, projection
raterisation,hidden surface elimination, shading
rendered image in frame buffer or stored on disk.

2.3 "How PRMan works" & Reyes algorithm

Rib file is parsed (scanned)
Primitives' bounds are checked to see if
they lie in the cameras frustrum ('vision') -
if not those 3primitives no longer need any calculations
primitives are checked to see if they are small enough for dicing
and if not - broken down or diced themselves into smaller chunks / sections
until they are small enough for the Reyes dicing
Reyes dicing into micropolygon grids
each primitive that is small enough is diced into a grid of micro-polygons
It is these micropolys that get shaded and eventually contribute to the
final pixel colors
shade at grid verts
bust the grid into individual micropolygons
each micropolygon is tested for bounds
incase a displacement shader has moved the position of the micropoly
each micropoly is then sampled at pre-determined sub-pixel locations
(There number of sub-pixel locations is set up as a control in the RIB file
or in the interface in the case of Mantra)
and a 'visible point list' is made with the Z depth values
the point list is then spatially blended and collapsed into a final pixel colour and opacity using filtering to weight between several samples for that pixel.
Some filtering algorithms you may have seen are:
Finally - the array of pixels is sent to a display buffer or saved to disk.
Post a Comment

Follow by Email