[Sidefx-houdini-list] First question to the list

Andrew D Lyons tstexture at gmail.com
Mon Mar 8 21:16:33 EST 2010


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_polar_and_Cartesian_coordinates

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
=======================================



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