Macha Posted December 18, 2010 Share Posted December 18, 2010 Is it possible to have a kind of displacement marching? I had an attempt at "displacement hair". See the image below or this link: There are various problems with it such as intersections and stretched mircopolygons. Would it be possible to displace in little steps, each time changing the displacement vector so that curved displacements could be made? The other day I happened to meet a clever TD at Siggraph and I was told that it is possible by shrinkwrapping. Now, I'm not sure I formulated my question correctly so this may refer to displacement animation, marching over the course of several frames rather than in one frame. Or it may be a renderman-only thing. I'm looking for something similar to ray marching in volumes, but for displacement. I have a feeling that would only be possible in the renderer itself, not on the shader level. Any thoughts on this? Quote Link to comment Share on other sites More sharing options...
Hazoc Posted December 19, 2010 Share Posted December 19, 2010 I think you can do multiple displacement passes just by doing several displacement vops in a row. Then slightly altering direction normals and the amount of displacement on each pass based on some field. Shrinkwraping could mean that you first displace your hair straight up along surface normal and then in second displacement pass you bend that hair towards the surface. Not sure where to get normal directions for that pass though. Quote Link to comment Share on other sites More sharing options...
Macha Posted December 20, 2010 Author Share Posted December 20, 2010 Something along those lines? You're right, the normals are wrong and it's not clear to me where to get them from. dispmulti.hip Quote Link to comment Share on other sites More sharing options...
pclaes Posted December 20, 2010 Share Posted December 20, 2010 (edited) Have a look at this thread, it might help you: http://forums.odforce.net/index.php?showtopic=6517&st=12 And the stupid renderman trick from 2003 in regards to the shrinkwrapping: http://www.renderman.org/RMR/Examples/srt2003/txBaking.ppt.gz And a shader that does nonlinear displacement mapping (1999): http://www.renderman.org/RMR/Examples/srt1999/index.html#nld http://www.renderman.org/RMR/Shaders/IDShaders/index.html#IDgloop Edited December 20, 2010 by pclaes Quote Link to comment Share on other sites More sharing options...
Macha Posted December 21, 2010 Author Share Posted December 21, 2010 (edited) Thanks Peter and Hazoc, it works for simple cases. Edited December 21, 2010 by Macha Quote Link to comment Share on other sites More sharing options...
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