# mattd

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Matt Daly
1. ## copy to the center of polygons

use a convert SOP, set output type to 'circles'
2. ## some matrix math help

nevermind, I figured it out, I think it's [a11 a12 0] [a21 a22 0] [tx ty 1] I keep answering my own posts, but hey, it helps to formulate the question to solve it. Thanks MD
3. ## some matrix math help

Hello, It's not really a houdini specific question, more of a matrices in general question, so I hope it is not a problem posting here. I have a program that outputs a transformation that I need to apply to a 2d image. I am trying to understand how to convert the format it outputs to a transformation I can use in a COP. Here is the description of the output of the program that I am looking for: Affine: (AffineTransform) An affine transformation is defined as: Tμ(x) = A(x − c) + t + c, where the matrix A has no restrictions. This means that the image can be translated, rotated, scaled, and sheared. The parameter vector μ is formed by the matrix elements aij and the translation vector. In 2D, this gives a vector of length 6: μ = (a11, a12, a21, a22, tx, ty)T . So I need to figure out how that 2x2 matrix and the tx and tx can get converted into values usable in a transform COP. I know that the explodematrix expression does what I need, but how do you work with the values I am getting? oh, and I need to do all of this with expressions, I can't use a VOP. Thanks for any help. MD
4. ## VRAY proxy output?

A friend of mine was told while at siggraph (by someone from Chaosgroup) that there would be some level of support in houdini to export proxy files to vray for rendering, or even a possibility for vray to work within houdini. Can anyone confirm or deny, or am I in NDA land? MD
5. ## od[force] Houdini 11 Wishlist

An easy to use network render queue. I mean really easy. And it works completely cross platform. And extensible via python so houdini really does become the pipeline in a box. A matter just came up for me - allow more control over how mental ray mi files are created. I just need control over custom text overrides. (ala the custom scene text section in maya) also, perhaps as part of the queue manager, I often prerender geometry, and it often is not multithreaded. Therefore I have to manually run a few houdini instances to use all my procs. If the ROP output node allowed multiple frames to render concurrently, it would be automatic. Of course it would fail if there were simulations, but I know that and there could be a warning. Include some pre-built lighting setup otl's, dumb it way down. Get some of the popular light rigs out there set up with some defualt shaders. Some off the top of my head: cornell box, room with a window, outdoor sunlight, npr scene, basic studio product lighting setup, etc. I want the keyframe CHOP from touch in houdini. MD
6. ## supress material assignment in mentalray

I am using the new mi assembly in 2009(or render proxy as they confusingly call it here and there). The mi file is referenced under the mesh shape node of a standin object in mental ray->Render Proxy. If I understand what you are doing correctly, you are doing this manually by swapping out the mi reference after maya creates it's mi file. I am not using standalone, so I cannot try it. This is by far the best solution I have found, since you never have to see the actual geometry from houdini in the maya interface (or you can load a non rendering stand in fbx), therefore maya can deal with it. It is my new fluids workflow and now I can totally replace realflow (rejoice!) Also, thanks for your help on the other thread, the motion blur works great. MD
7. ## supress material assignment in mentalray

I am writing out a mi sequence for use as an assembly file in Maya. It works well, except that I have to prune out the material assignment so that the material can be overridden in maya. For now, i am using a text editor to search and replace the assignment with a blank space material ["/obj/particle_emitter1-mat"] <--- have to remove this line from the mi file it would be great if I could just get houdini to not assign the shader at all, is there some way of overriding the instance section with custom text within the ROP? MD
8. ## running a ROP from DOS, with a frame range argument

ok here is a solution: in muster, I have a 'custom job' that launches cmd.exe muster then wants a arguments string, with <SF> and <EF> to distribute chunks to machines. these have dos backslashes /C "C:\Program Files\Side Effects Software\Houdini 9.5.379\bin\hython" \\10.1.2.10\chicagowip\_PROJECTS\2009\blahblah\06_3D\houdini\render.py &lt;SF&gt; &lt;EF&gt; here is the script, with hard coded paths to get this running quick: import sys, os, hou args = sys.argv start = args.pop() end = args.pop() os.chdir("\\\\10.1.2.10\\chicagowip\\_PROJECTS\\2009\\blahblah\\06_3D\houdini") hou.hipFile.load("blahblah.hip") hou.hscript("render -V -f " + start + " " + end + " /obj/particle_emitter1/ropnet1/mentalray1") I know I should use the new HOM render command, but I have not gotten into it quite yet. Hope it helps someone, MD
9. ## running a ROP from DOS, with a frame range argument

hrender needs csh to run, and I cannot get the render queue to run it properly from a single dos command. I can start the csh, but then i cannot pass the command with the frame overrides. however, I did find a python solution, and I have it working now. I'll post it in a bit to help future queries. MD
10. ## running a ROP from DOS, with a frame range argument

Ok, I am coming down with a cold so I am not thinking totally straight... I have been searching but most related topics are either on linux or via cygwin, I have neither I need to distribute a chain of complex SOP ops that write to a bgeo sequence across a farm using Muster, and it only supports single dos commands. I need to run a command like: hscript render -f 1 10 /obj/geo/out/geometry In muster I have to use a wildcard to replace the 1 and 10 to do the slicing. Therefore, calling an external script does not work. I hope the question makes sense. MD
11. ## How brave are you?

Does anyone have a good link to info on obscure amiga file formats? I have stuff created in imagine 3d, Art Director Pro, deluxe paint, and a whole sequence I would love to convert that is written in some mjpeg format for an external box (dfilm, or dtv, or something like that) I would be happy to embarrass myself in exchange for help, this stuff is from 1992 so you know you want to see it. MD
12. ## using .mi files to render deforming geo in maya

here is the simple mel expression to animate the .mi sequence setAttr -type "string" fill_MIproxyShape.miProxyFile (("houdini/mi/fill8.")+ (`currentTime -q`) +(".mi")); sadly, motion blur does not work, I am guessing that there could be a solution to get it to blur when making the .mi files, but I have to research more. The editing of the files was simple, I used notepad++ to remove the line where the material is set in the file sequence, so I did not have to mess with a script. The other thing is the bounding box, maya sets a line up in the comments section. If you don't care about optimizing for objects that go out of view, you can just make it really big. # assembly root bbox: -1000 -1000 -1000 1000 1000 1000
13. ## using .mi files to render deforming geo in maya

I have been banging my head on the wall trying to get a fluid sim to render within a maya scene I have been using fbx export but ran into a bunch of issues: -the polys come over as separate polygons that need to be merged in maya. maya is very touchy about this and gets very slow and painful to manage, especially on big objects -the fbx format seems to have a 2GB limit on vertex caches -houdini does not seem to support exporting a cache per frame -then in maya, the mesh still needs smoothing, which is too slow so I just tried something new : I exported the object as a .mi file sequence and it does work with a few caveats that require some meddling You can use a .mi file within maya in a proxy workflow -I can't seem to get houdini to not set a default material, so I have to delete it out of all the .mi files so maya can reassign -I am a little unsure about the whole bounding box thing, working on it -maya of course does not do simple things like file\$F.mi so a script has to be called from the pre render.mel to set the current frame. I'll post it when I get it working better. So a question: is there a way to call custom text in the mental ray ROP? it seems like it does not have a lot of control, but then again this is my first time to mess with it. I want there to be no call to a material or a 'render' statement when the .mi file gets written. Right now I need to write a pythons script to go in and delete them after the fact. the other bonus is that maya renders this actually pretty fast so I am happy to find that this works even with the caveats. MD
14. ## Pbr?

when it comes to pbr, I always think of this:
15. ## export format that supports multiple uv sets?

hmm, I have been trying them with no luck. I have tried point and vertex uv's, and the second set is always ignored in maya. FBX export from maya with multiple sets does work. Also the fbx file that houdini puts out reads back in fine to houdini. I think the maya import may be buggered. I'll slink off to a maya forum now.... I am pretty sure obj files don't work, since the export/ then reimport to houdini loses the multi sets.
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