= osgNature =
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== Rendering of huge amount of trees (osgNature) ==
Approches to render forest and/or trees in real-time
 * '''Billbords'''
 * '''2-crossed-Quads'''
 * '''Matrix-transformed crossed Quads'''
 * '''2-crossed-Quads batched in geometry chunks'''
 * '''preprocessed billboards based on tree geometry with LODs'''
 * '''points to display forests and billboards as trunks'''[[BR]]
for reference: from a quick peformance test (using modified osgpointsprite) of rendering with unlit point sprits when not fill limited achieved 39 million points a second, or with just points 91 million/second.  Tests carried out on a AlthonXP2600 + GeforceFX5900XT using 100 blocks of 10,000 points stored in osg::Geometry with display lists (VBO's produced slightly lower results!).  Same tests carried out with one light on, 32 million point sprites/second and 54 million points/second.
 * '''volume rendering of single or groups of trees'''
 * '''pre-computed impostors for single trees'''
 * '''[http://www.infiscape.com/doc/parallax_mapping.pdf parallax mapping] & [http://www.reallyslick.com/downloads.html example code] - used both on indivual trees (a fives visible sides of cube?) or as a tree wall and canopy.'''


First approach generating point trees out of images: (tree with 7000 points made from 128x128 image)[[BR]]
[[Image(pointtree_7000_points.jpg)]] [[BR]]
(thoughts: smaller images would lead to less points. quality would no suffer, since it is only an LOD level)

== Generate Trees (to populate the forest) ==

 * '''Arbaro'''

A great GPL external project here:
http://arbaro.sourceforge.net/

Here are 2 scripts for automatically generate textures from the arbaro .xml tree definition, thru povray. 
TGA texture with alpha is generated, as the corresponding depth-map (for depth-map, you'll have to install megapov. See render_pov_to_textures.sh for more informations).
As now, it is still work in progress, but may be usefull for those who want to test forest populated with good-looking trees/textures. (fmarmond@users.sf.net 2005-01-10)
(shell file name appened'.txt' for wiki security reason)
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[attachment:generate_xml_to_textures.sh.txt.sh generate_xml_to_textures.sh.txt]
[[BR]]
[attachment:render_pov_to_textures.sh.v2.txt.sh render_pov_to_textures.sh.v2.txt] (oops, it was an error in the file, new one uploaded 2005-01-13)