murathan altunsoy Posted December 30, 2015 Share Posted December 30, 2015 (edited) or How we can do in houdini ? Edited December 31, 2015 by murathan altunsoy Quote Link to comment Share on other sites More sharing options...
amm Posted December 31, 2015 Share Posted December 31, 2015 (edited) About first, generally you interpolate the relative, parametric UV location from first polygon, to extruded ones. These positions are control points for some kind of curve interpolation. Let's say in Houdini, Scatter SOP from initial set of polygons, XYZ distance VOP to find parametric UV, Primitive Attribute VOP for matching, Spline VOP to fit the lines on curves, while lines are copied from points. There should be a mechanism to find the corresponding polygon - I think this part should be easier in H if sort of copying is used (polyextrude with 'side' option off, or like), because H XYZ distance VOP returns the primitive number, too. About Melena 'hair from nurbs', basically it's 'boosted' H Creep SOP or what is called 'deform by surface' in SI or 'wrap' in Maya. However, to get it 'boosted', there's need to re construct the functionality with VOPs or something else. Here in 'finished work' section, there is a sort of translation to H, of SI ICE hair system, which was inspired by one Melena's predecessor, having a lot of appropriate trickery inside - not the same as Melena, anyway. Note that, if something like believable hair is goal, work seems to be similar to building a rig for character - while nothing of required knowledge belongs to rocket science, only after few complete iterations, from scratch to final and believable result - you'll know what's 'appropriate' solution. So maybe it's best to create a 1:1 copy of some well known, widely accepted solution. Of course if related, possible copyrights allows such approach. Edited December 31, 2015 by amm 1 Quote Link to comment Share on other sites More sharing options...
mestela Posted January 1, 2016 Share Posted January 1, 2016 (edited) I'd already started down the path amm suggested, but hit a problem; a copy sop will keep the parametric uv's identical for each copy, but a polyextrude doesn't guarantee this. Even with turning off sides and leaving front+back on, the parametric uv's flip almost at random per poly (I'm assuming this is becuause the point order doesn't stay consistent, therefore parametric uv's also can't stay consistent). Using texture-uvs (from a uv quickshade or similar) do stay intact with polyextrudes, but then you run into the problem that you can't use primuv() to look this up. Bit of searching around and stabbing, came up with this solution: assign a unique @id to the starting grid, assign texture uvs (point uvs rather than vertex uvs) scatter points, store id, uv per point after you've made all your polyextrudes, flatten them all into texture uv space (@P=v@uv;) use findattribval() to lookup by @id all the matching prims for a given point use xyzdist to lookup the prim in texture-uv space return its matching parametric uv use primuv() to lookup that world position on the original polyextrudes Modelling with polyextrudes is a bit of a chore, you have to keep enabling front+back, disable side for each go-round, also, I found I got most consistent results by manually selecting each time; I thought I could use the groups and have it reset the group on each extrude, but it didn't work. I must be missing something. Anyway, good challenge. hair_from_extrudes_v02.hipnc (edit, added colour and width mappings, slightly betterer modelling) Edited January 2, 2016 by mestela 1 Quote Link to comment Share on other sites More sharing options...
Mzigaib Posted January 2, 2016 Share Posted January 2, 2016 (edited) Those videos show great ideas, I am going to pay more attention to XSI videos since they have a different way to present great solutions it`s only a matter to port them to Houdini, thanks for those by the way. Here is my contribution, my approach to mimic the 1st video was more a VOP SOP method and I had the same problem that Matt with the polyextrude and the uvs consistency but I don`t think that is that bad, actually I think it is a great solution to model strands, thanks again for the XSI videos. And to mimic the 2nd video was like more straight forward using foreach to create strands from a nurbs esphere, off course with a more complex shape you have to rethink your methods but totally possible to do, it is a great start method to create your own procedural guides to use with Houdini fur asset. Both methods are just prototypes with just a couple hours with try and error they can be much improved and then turn into digital assets for re-use later, I really like the way Matt used wrangles to create the points according to uv space. That`s what`s cool about Houdini you have a lot of ways to achieve the same solution. I hope those files can help. Cheers! model_opt1_03.hipnc model_opt2_01.hipnc Edited January 8, 2016 by Mzigaib 3 Quote Link to comment Share on other sites More sharing options...
murathan altunsoy Posted January 4, 2016 Author Share Posted January 4, 2016 Thank you so much.Your suggetions and solutions are really awesome Quote Link to comment Share on other sites More sharing options...
murathan altunsoy Posted January 8, 2016 Author Share Posted January 8, 2016 i did a few example 1 Quote Link to comment Share on other sites More sharing options...
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