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My initial works on fluid from particles was handed over to Janne Karhu, module administrator of the particle system at the time. It was already integrated after Blender 2.5
Blender Volumetrics was made official in Blender mainstream, integrated and further developed by the render module administrators.
The sources can be retrieved through a subversion client (no password required) at the following address
You can directly download blender builds with volumetric rendering (named blender 2.5) from graphicall.
Its license is GPL :
This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation,
Inc., 59 Temple Place – Suite 330, Boston, MA 02111-1307, USA.
The Original Code is Copyright (C) 2001-2002 by NaN Holding BV.
All rights reserved.
Contributor(s) to the volumetric renderer:
Initial contributor for the volumetric code: Raúl Fernández aka Farsthary
New volumetric renderer: Matt Ebb aka Broken, hired by Promotion Studio/Red cartel
Light cache based multiple scattering approximation, initial voxeldata texture code, Depth cutoff threshold:Raúl Fernández.
Trilinear interpolation adapted from PBRT
Tricubic interpolation from libtricubic
VFX integration and optimization: Daniel Genrich aka Genscher (smoke simulator) and Janne Karhu aka Jahka (particle system)
VFX original algorithms: Niels Thuerey et al.