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[Sidefx-houdini-list] First question to the list
Wednesday, 10 March 2010 Wed, 10 Mar '10
Alex, BTW, in the isosurface node those algebraic surfaces should go something like this: e.g. the Calyx, x2+y2z3 = z4 becomes $X*$X+$Y*$Y*$Z*$Z*$Z - $Z*$Z*$Z*$Z. Just enter it into the implicit function parameter window and you're done. No trig required hehe. Your (y4 - x4 + a y2 + b x2 = 0) would just need some numbers of your choosing plugged in for a and b. best, david ________________________________ From: Alex Czetwertynski <alex at franktheplumber.com> To: sidefx-houdini-list at sidefx.com Sent: Wed, March 10, 2010 4:14:42 AM Subject: Re: [Sidefx-houdini-list] First question to the list Thanks Andrew I was not able to get the formatting right, even by copy pasting into a text editor (I'm on a mac...), but I just recreated the network based and it worked fine. My knowledge of mathematics is probably too basic to understand exactly what is going on, as I was trying to figure out how I could plug the following cartesian equation (y4 - x4 + a y2 + b x2 = 0) into a similar setup, but have to admit I have no idea. Will go back to Trig 101 before I keep asking questions about this.... Thanks for your help, at least I now have a nice Lituus curve! Alex On Mar 8, 2010, at 6:16 PM, Andrew D Lyons wrote:
This site is using mostly polar coordinates. Houdini uses mostly cartesian coordinates: http://en.wikipedia.org/wiki/Polar_coordinate_system http://en.wikipedia.org/wiki/Cartesian_coordinate_system http://en.wikipedia.org/wiki/Polar_coordinate_system#Converting_between_p... In any case to model something like this in Houdini you to set up extra points to sample, and then do a conversion to cartesian as you go. Take a look at the point SOP in this network: (Drop this script in a textport in Houdini - watch out for line wrapping from the email:) --------------------------------------------------------- # Automatically generated script: Monday March 08, 18:11 \set noalias = 1 set saved_path = `execute("oppwf")` opcf /obj # Node Lituus (Object/geo) opadd -n geo Lituus oplocate -x 3.69 -y 0.286303 Lituus opset -S on Lituus opparm Lituus use_dcolor ( off ) chautoscope Lituus +tx +ty +tz +rx +ry +rz +sx +sy +sz opset -d on -r off Lituus opexprlanguage -s hscript Lituus opcf Lituus # Node file1 (Sop/file) opadd -n file file1 oplocate -x 0 -y 0 file1 opset -d off -r off file1 opexprlanguage -s hscript file1 # Node grid1 (Sop/grid) opadd -n grid grid1 oplocate -x 11.8336 -y 5.95065 grid1 opparm grid1 rows ( 100 ) cols ( 1 ) opexprlanguage -s hscript grid1 # Node point1 (Sop/point) opadd -n point point1 oplocate -x 11.8668 -y 4.82124 point1 opparm point1 numcustom ( 1 ) chblockbegin chadd -t 0 0 point1 tx chkey -t 0 -v 0 -m 0 -a 0 -A 0 -T a -F 'cos(ch("weight"))* 1/sqrt(ch("weight"))' point1/tx chadd -t 0 0 point1 ty chkey -t 0 -v 0 -m 0 -a 0 -A 0 -T a -F '$TY' point1/ty chadd -t 0 0 point1 weight chkey -t 0 -v 1 -m 0 -a 0 -A 0 -T a -F '$PI *($PT/18)*90' point1/ weight chadd -t 0 0 point1 tz chkey -t 0 -v 0 -m 0 -a 0 -A 0 -T a -F 'sin(ch("weight"))* 1/sqrt(ch("weight"))' point1/tz chblockend opparm point1 t ( tx ty tz ) doweight ( on ) weight ( weight ) opset -d off -r off point1 opexprlanguage -s hscript point1 # Node delete1 (Sop/delete) opadd -n delete delete1 oplocate -x 11.8668 -y 3.86161 delete1 chblockbegin chadd -t 0 0 delete1 rangeend chkey -t 0 -v 0 -m 0 -a 0 -A 0 -T a -F '$N' delete1/rangeend chblockend opparm delete1 entity ( point ) pattern ( 0 ) opset -d off -r off delete1 opexprlanguage -s hscript delete1 # Node null1 (Sop/null) opadd -n null null1 oplocate -x 11.8668 -y 2.98478 null1 opset -d on -r on null1 opexprlanguage -s hscript null1 oporder -e file1 grid1 point1 delete1 null1 opcf .. opcf /obj opcf Lituus opwire -n grid1 -0 point1 opwire -n point1 -0 delete1 opwire -n delete1 -0 null1 opcf .. opcf $saved_path --------------------------------------------------------- Cheers On 8 March 2010 17:35, Alex Czetwertynski <alex at franktheplumber.com> wrote: > Hello > > This is my first post, been lurking around for a while... > Been using Houdini for only a few months, so excuse the newbie tone > of > this question... > > I'm interested in using Houdini to create shapes of this sort > http://xahlee.org/SpecialPlaneCurves_dir/specialPlaneCurves.html > > What would be the way to go about creating, say, a Lituus shape? It > seems to me that the type of equation that is being used contains > symbols that I have never seen in Houdini, but I could be wrong. > > Thanks! > Alex > _______________________________________________ > Sidefx-houdini-list mailing list > Sidefx-houdini-list at sidefx.com > https://lists.sidefx.com:443/mailman/listinfo/sidefx-houdini-list > -- ======================================= Andrew D Lyons | Digital Artist | http://www.tstex.com ======================================= _______________________________________________ Sidefx-houdini-list mailing list Sidefx-houdini-list at sidefx.com https://lists.sidefx.com:443/mailman/listinfo/sidefx-houdini-list_______________________________________________ Sidefx-houdini-list mailing list Sidefx-houdini-list at sidefx.com https://lists.sidefx.com:443/mailman/listinfo/sidefx-houdini-list