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How to get my gras over a landscape?


brain

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Hi,

I modelled a landscape and a grid of gras. Now I want to get the gras copied over the landscape. But the COPY SOP doesn't really function the way I want it.

The sample file can be wonloaded here:

http://stud.fh-wedel.de/~mi4236/gras.zip

Hopefully anybody can help me.

The Problem is that I am using version 4.1 of Houdini, so if you are using a 5.x version I am not able to open your file. So it would be nice if you could just post how to get it to work.

Thanks

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hey there brain,

consider this method, it should work in 4.1

[first network - ground]

grid - nurbs or poly, doesnt matter, can convert

- size - 10x10

- rows/columns - 10

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fractal - divisions - 2 or 3

- adjust other params to taste

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divide - toggle "bricker polys"

- size - depends how dense you want the grass, try .08

note: i usually turn this off until im ready to render, it can get very

dense :)

[second network - grass]

- plop down 2 curve sops & model them differently, use 4 pnts to create the nurbs curve..any more than that is unecessary.

- append point sops to the curves, i have the following expressions in the x,z Position field:

x: .1*sin(($F*3)+($PT*36))+.1

z: .1*sin(($F*1.5)+($PT*36))+.1

you can copy the same expression into the 2nd point sops x,z positions as well...but youll need to tweak it

- append transforms to the points...dont adjust anything just yet

- pipe the xforms into a switch sop...no adjusting yet

- append an attribcreate sop & in the "Name" field type, width

- default - .002,.002,.002

- value - .001,.001,.001

note: values are micro for thin blades...if you want fat hefty ones, crank

the values up. you wont see this until you render.

- leave the other params as is...or if youre bored, tweak 'em

- append a copy sop to the attribcreate sop

- toggle off rotate to normal & transform cumulative

- jump to the stamp folder, and plug these digits in:

var1 - which, param1 - rand($PT)*1

var2 - sizer, param1 - rand($PT)*.7

note: once all this is done, play with the expressions values, youll

see what they do

- set down a shop sop and go to SHOPs, set down a hair shader and

make it grassy in color...set the shiny attribute to something low, 1 for

example

- go back to your transform sops, toggle off "pivot about group centroid"

- in the uniform scale plop in the variable you just made in the copy sop

param("sizer",0)

- do the same for the other transform sop

- go to your switch sop, and in "select input", type this

param("which",0)

pipe the 2 networks into a merge sop and render...should have a thick head of grassy stuff... render out geo files for a somewhat less computation heavy scene :)

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