Category Archives: Tutorials

Tutorials I’ve done.

VOP COP Raster Depths

This was an odd video to do since it seems to be a simple topic but when talking about it out loud it starts sounding complicated. I’m basically covering several sub-topics which support the overall topic. Despite the confusing ramblings in the video, what you should take away from it is that in VOP COPs, the “Raster Depth” setting can cause results to vary depending on the data generated inside.

The hip file I’m using is actually based on a workshop that used to be online (but doesn’t appear to be anymore). I used it because it had the exact components to demonstrate everything.

Also, I’m sure my friend Jason will say that he is in no way regal when it comes to compositing, but seeing what he’s been up to lately certainly indicates that he knows what he’s doing :).

Varying Materials Using A Single Shader

Nothing ground breaking here, but for someone who is into neat little tricks to control shaders, I thought this was worth showing. What the video covers is a way to vary the materials on a single object using a single shader (differing from the usual method of using multiple shaders for different pieces of an object).  I’ll leave it at that and let the video do the talking. I’m starting to record at my screen’s native resolution (1680 x 1050) which ups the video size but I like seeing big videos.  I’m also posting these on Vimeo which I think is nice to have since you’re not always on a machine that you can download videos on.

Note: Video re-done on 5/25/2009. I thought it could be cleaner and more focused on production nuances so I re-recorded it.

Image Planes Part 4 (Object IDs)

Didn’t think the image plane series was complete enough so I tacked on this little diddy. I covers how to get object (or primitive) ids using image planes in Houdini and what you can do with them in the compositor using the lumakey COP. The compositor part I learned from SYmek, who I feel is an integral part of the Houdini community (and who I had an argument with about points on the Sunflow forum a while back 🙂 ).

Image Planes Part 3 (Light Export)

I’m fairly pleased with this video only because I learned a lot on my way to get this worked out. Well, I learned a lot of mistakes one could make with Houdini’s VEX like what you shouldn’t put in illuminance loops. I felt obliged to do this video since in the very first video I mentioned that I would talk about light export in the image planes. What this covers is how to get planes/passes for each light in the scene. You can find the video as well as the final hipnc file here. The final hipnc file has specular components added which I didn’t cover in the video since the technique to get the diffuse planes is so similar.

Image Planes Part 2 (An Occlusion Plane)

Okay, so I went a bit off the track on this one. It’s loosely an image plane video and more of a “how to do an occlusion pass inside a shader then put it in a plane” video. So I’m not sure if I should keep it under the “image plane” heading or create some new one. Either way, this topic was a weird one I was wrestling so I did a lot of forum searches and made lots of mistakes (basically writing my VEX poorly). So I thought I would at least show my results so people could see what I found. What’s made this more interesting is looking into the different occlusion functions and trying to figure out why they differ and what they really give you.

Edit: In this video I use a subtract node to subtract the occlusion output from a constant float (1). Houdini user Jason M. pointed out that I could have used the compliment VOP instead which does the same thing in one node rather than the two I used. So remember that the compliment VOP is around!

Using dophassubdata To Change Colors Dynamically

It’s a fairly straight forward but I thought it needed to be put in video form. Dynamics and expressions in Houdini go hand in hand and this is an example of that. You can find the video tutorial on how to do this here and the result below:

Dynamic Color Changing from Geneome on Vimeo.