Painting points on a surface in a consistent non-random way.

[Ankit Pruthi]

Hey guys, recently i started learning houdini since i need to make some forests for a personal project (may sound noobish but its not, and will probably take a long time to make).

I've already made a few different plants and trees in blender for that.

Coming to the questions i had, i saw the tutorial "paint by culling" on old school blog on sidefx.com. This method works by deleting the surface after scatter sop scatters points, and hence it appears as if one is painting points over the surface and they are not randomly generated each time a stroke is made.

It works really well in conjunction with instancing on points to paint things like grass etc on low poly surface.

However i wanted to use a similar technique to paint instanced trees on detailed geometries..

Now the issue is, with heavy geometries, that method tends to be slow i.e. my computer starts to crawl since deleting high polygon meshes is heavy on it.

Is there any other way of placing points on a geometry where they are not randomly generated all over again when someone paints on it?

What i was trying to achieve was that if someone paints points, they must stay there, and if someone paints over them again, more points should be added. And if needed, they can be moved around or deleted.

Any suggestions or hints on what direction i should be headed in??

I really wish scatter sop didnt re-distribute points randomly each time. I believe there would be other ways of generating/distributing points which i am completely unaware of at the moment. I did try looking through the forums or asking friends but couldnt find much info on this. Most methods i came across still placed points randomly.

Thanks for the help!!

[Macha]

Perhaps you could have some base points with that previous method. Then, when you paint over you create a new attribute that you use to determine a copy value and use that to copy the existing points. Then use an id on these points as a dimension in your noise space and displace them. I think this could be made to work. Whether it is fast enough, I dont know.

I have tried something similar to this to fill spaces with huge amounts of points and found it very fast, much faster than scatter alone.

Or wait for H12

Edited February 4, 2012 by Macha