a question about "ReadAchive"

[ykcosmo]

I know a way that I can use "ReadAchive"(ribbox in mtor) to insert RIB content into the current render scene. So, how can I use "ReadAchive" to render proxy object? For example, I created some boxes, and how to use "ReadAchive" to instead these boxes to detailed models when rendering?

[stu]

1. Write out the hi res geometry as you normally would for the archive.

2. Put a box at the SOP level which defines the bounds of the hi res geometry. Make sure that the box has the render flag on (display flag doesn't matter).

3. At the object level in the render tab, set Geometry to "Bounded File (Render SOP defines bounds)" and point it to the archive that was written out in step 1.

Should be good.

stu

[ykcosmo]

thank you for your help! I have accomplished it!

and I have another question:

I wrote out the hi res geometry , and I put a box at the sop level, then I used a copy sop connected with the box sop. but I can only set geometry to "Bounded File (Render SOP defines bounds)" and point it to the archive file. can I render the hi res geometry instead of each box of the copied boxes with this method???????

[stu]

I think I know what you're getting at, but correct me if I'm wrong...

The best way to do what I think you're talking about is through instancing. Leave your original object as is (the hi res geometry file read with the box with the render flag in the SOP level). Make sure that the geometry you've written out is at the origin or you'll inherit it's transformations in addition to it's new location(s).

Here's the change: put down another geo object and on the inside, create the locations where you want to see the copies with points. This could be done with any type of geometry. For example, if you were to put a box down, you would get a copy of the instanced geometry at every point in the box. If you were to use a particle system, you would get an instanced object at every particle. It's also important to remember that the instanced geometry will obey both normal and up vector directions.

Now, at the object level of the new object you've just created with the points inside, go to the Render tab and turn on "Point Instancing" and point to the original geometry object (the one with the box inside and the reference to the hi res geometry at the object level) in the "Point Geometry" field.

When you render, you should get a copy of the hi res geometry at each point with every advantage that writing it out as an archive gave you as well as the advantages of using instanced geometry.

stu

[ykcosmo]

thank you. it is nice.

and copy sop creates copies, besides point instance, is there another way to get instance?

[edward]

Geo Instance under the Render tab of the Object parameters?

[stu]

What Ed said.

[ykcosmo]

thank u!!!

[bmcgee21]

how about adding color to each instances shader based on point attributes? any ideas on how that would be done?

[TheUsualAlex]

how about adding color to each instances shader based on point attributes?  any ideas on how that would be done?

25363[/snapback]

Typically adding color to instances are pretty much the same way you'd pass colors attributes to from your geometry point to control colors in your shaders. However, as for doing point instancing, you'd have to attach string attributes for your shaders. So, when you have tons of geometry where each instances have varing colors, it's best to keep your shaders to the barebone.

In your Shader SOP, turn off the User indirect References and turn on Generate Point Attributes for Instancing. Then RMB on that sop and look at all the attributes through spreadsheets for the shader string. Once you find this, you should be able to start tweaking away shader string to suite your needs...

I know there's an old video tutorial on this somewhere...

-Alex

[bmcgee21]

Alex,

thanks for the quick response, i'll give that a try right away.

[bmcgee21]

Thanks Alex!

That worked perfectly, I'm actually using it now to change the shader string to a tcl runprogram script that generates geometry in memory based off of point attributes. Thanks a ton, I've been grinding at this forever.

[deecue]

I know there's an old video tutorial on this somewhere...

yea, i think that was one of pbowmar's.. a great tut.. i have it around here somewhere and could upload somewhere if needed and hope that my server won't get slammed.. marc, did you guys ever get a chance to back up all those legacy vids and docs? a shame they're not around anymore..

aha! here we go.. found these:

http://sidefx.vislab.usyd.edu.au/houdini_v..._instancing.avi (this is the instancing vid..)

http://sidefx.vislab.usyd.edu.au/houdini_video/index.htm

http://sidefx.vislab.usyd.edu.au/cd2_5.5.151/start_here.html

http://oldsite.vislab.usyd.edu.au/resources/guide/houdini/