[Bf-committers] qdune review

[Ton Roosendaal]

Hi,

Brecht, Campbell and I sat down for an afternoon checking on the status  
of the micropolygon (qdune) renderer. Although we agree it's extremely  
useful and has superior features, the integration of this system (i.e.  
to use all required Blender features) will take so much additional work  
that we decided to put this on hold for a while.

The immediate short term target for Brecht is to get the particle fur  
system to render, using improved storage and rendering tricks, but  
within the current rendering system. We also will look at using some  
kind of bucketing (generation of geometry data per tile).

This is a summary of the status of qdune integration now:

- added exporting API, shared by Blender internal as well as qdune.  
Exports mesh/curve/surf geometry.
   (note, this is similar to the GSoC project, but different  
implementation)
   (note, it can be used for other exports too)

- added qdune code for preparing rendering data to be handed over to  
Blender internal shading
   (texture coords, lamp coords, etc)

- almost working: shadowbuffer rendering

- to be done: irregular buffers, halos, envmap, renderlayers, passes,  
lamphalos, threads
   (main reason for postponing it)

- to investigate: speed of the qdune system is below expectation  
(slower than Blender internal in comparable shots). Maybe the biggest  
gain is in more complex situations

- to be done longer term: raytracing (AO, shadow, mirror), panorama  
render, ...

To be able to make a decision, we also listed the pros and cons for  
adopting a micropolygon system in Blender:

Pro:
- Displacement mapping, motionblur
- Unified render (transparent, solid)
- Support for big scenes, because of efficient bucketing
- Better anti aliasing (for shading too)
- More efficient shading (cache misses)

Con:
- Raytrace is hard to integrate (AO, softshadow)
- Still relatively slow compared to Blender
- Lots of work still to get it on functional equal level...
   (shadowbuffers, envmaps, halos, lamphalos, render layers, passes,  
threading, ...)


Brecht definitely is willing to work on further integration later.  
But... would help if we could find a partner for him to check on the  
integration work and maintenance.

-Ton-

------------------------------------------------------------------------ 
--
Ton Roosendaal  Blender Foundation ton at blender.org  
http://www.blender.org