I'm with Ivan. Comets don't do much.
Procedurally:
1./ grid sop - poly - divs 8*1 - size 1*1 - center 0.5,0,0
2./ point sop - Use alpha. set to $TX
3./ copy sop - make 20 cumulative copies with random length scaling in X
4./ set up a ramp in COPs. make colors transition like picture
5./ use $TX to index into ramp to get point color
6./ primitive sop - rotate some random amount around z axis
7./ copy spheres to points (pscale (point sop) will effect each scale. transfer attributes (Cd, Alpha)
8./ shader with alpha para/perp (use dot product from I and N to scale opacity)
or something like that.
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Technical Discussion » Making a comet looking like this:
- tstex
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Houdini Lounge » New dynamics video tutorials,
- tstex
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I wasn't responding to your post Symek. You're good.
After reading Pagefan's post, I went to what he was referring to in the Houdini on Mac thread. There was a discussion there about civility on the forums. I was tying that back into this thread.
Peter has done a lot of great work teaching and creating education material for Houdini. People need to be more careful.
http://en.wikipedia.org/wiki/Collegiality [en.wikipedia.org]
After reading Pagefan's post, I went to what he was referring to in the Houdini on Mac thread. There was a discussion there about civility on the forums. I was tying that back into this thread.
Peter has done a lot of great work teaching and creating education material for Houdini. People need to be more careful.
http://en.wikipedia.org/wiki/Collegiality [en.wikipedia.org]
Houdini Lounge » New dynamics video tutorials,
- tstex
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One of the reasons people are generally very civil on these forums is that people want to get paid to do what they love. As a Houdini user, many of the people you might work with (or their friends) are here. That includes many of the people who make the hiring decisions for companies that use Houdini. There are only a finite number of places in the world where you can work in this industry. You can seriously smoke years of career development or permanently remove great opportunities for the rest of your life with a few poorly chosen words. It's good to think about that. Express it in terms of a large amount of whatever currency is of most value to you. From that point it's hard to come up with intelligent reasons to justify pouring pollution into the pond - when so many stand by watching. You get what you give.
Technical Discussion » pops torque and tumbling metaballs
- tstex
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I wish this forum cached entries. I carefully wrote up a solution to this only to have a houdini help server open in another tab crash my whole firefox session.
nevermind. Here's a short version.
Use Sops for more control. Pops are great for position and velocity but make controlling rotations very difficult. Turn on particle gnomon in viewport to see rotations.
You need to animate a curve along the central axis of your plume/flow. Use tangent SOP to flow normals along curve(watch 1st and last point N). Copy P into a vector called “pos” and N into “flow” vector using attr create.
The rotate VOP rotates a vector around an axis using an angle (in radians). You need:
nevermind. Here's a short version.
Use Sops for more control. Pops are great for position and velocity but make controlling rotations very difficult. Turn on particle gnomon in viewport to see rotations.
You need to animate a curve along the central axis of your plume/flow. Use tangent SOP to flow normals along curve(watch 1st and last point N). Copy P into a vector called “pos” and N into “flow” vector using attr create.
The rotate VOP rotates a vector around an axis using an angle (in radians). You need:
- * a make_transform VOP hanging with no inputs.
* A vector to rotate (normalized N or v probably) (See below)
* An angle parm (convert from radians maybe). (you probably want to override this float to be a function of particle life or proximity to plume/flow curve.)
To get the axis vector:
* you need to use attr transfer pull the near point “pos” and “flow” off your plume/flow axis curve.
* Create a vector “near” from your particle to the curve nearpoint by subtracting your particles P from pos.
* take a cross product from your “near” and “flow” vectors. Feed into axis parm of rotate.
Export the rotated n or v.
Much of this could be in one VOPNET.
Houdini Indie and Apprentice » VOPS -> vopsurface OGL Diffuse expression
- tstex
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Not quite sure what you are trying to achieve.
I'm going to assume that you have created a SHOP surface definition using a VOPnet. After that I'm not quite sure. This: ch(“/shop/material1/vopsurface1/output1”) makes me concerned that you are trying to call a surface shaders output from another nodes parm - which is not possible.
What exactly are you trying to do?
I'm going to assume that you have created a SHOP surface definition using a VOPnet. After that I'm not quite sure. This: ch(“/shop/material1/vopsurface1/output1”) makes me concerned that you are trying to call a surface shaders output from another nodes parm - which is not possible.
What exactly are you trying to do?
Technical Discussion » attribute name rule?
- tstex
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- Here's an alternate version:
Attributes:
* Attributes are user defined data objects that can be “embedded” in your geometry.
* RMB on a SOP, and open a “Spreadsheet” to see a full display of your attributes.
* Attributes can be different types (int, float, float3, vector, string)
* Any of these types can be applied to different levels of detail in your geometry structure. (vertex, point, primitive, detail). As an example you can have a per-point float attribute, or a detail float attribute that applies to all the geometry.
* User created attributes are lowercase by common convention. It is possible to have user created mixed case or upper case attribute names, but the code police will generally frown on you. (Exceptions include some SESI factory attributes such as P and N which use an old CG (prman etc) convention for such attribute names to be short and capitalized.)
* Attributes can be manually user generated in vex/vops (addAttr, Parameter export) or using the attribute create SOP.
* Attributes can be auto-created by a number of SOPs. As an example, the various “Compute Normals” SOP toggles will add an “N” attribute
Variables
* Variables are like “pointers” or “aliases” to your attribute data. They are merely a shorthand way to look up a particular attributes value.
* Technically, (and without getting into python yet) there are 4 types of variables that can be used in parameter expressions in Houdini. 2 are pure geometry variables, and 2 are hscript variables that do not point to geometry attributes. We're mainly talking about geometry here, but it's good to be aware of the 2 hscript variable types:
- Local hscript variables - Local to a particular hscript .cmd file. These are set in a .cmd file, and die when that .cmd script finishes running. For more information enter “help set” in a textport.
- Global hscript variables - Things like $F $PI or $HIP. Alt-Shift-A to see more. Do “help setenv” in a textport for more info.
- Geometry Local variables - Auto-created from attribute data by certain SOPs. Only exist in that SOP and dis-appear in next SOP in chain. The point SOP is a good example of a SOP that has these.
- Geometry Detail Defined Variables - These user defined variables are created by users in atrribCreate SOPs, addattr VOP etc. These variable mappings are stored in a “varmap” detail attribute, and thereby persist across multiple SOPs. These are uppercase by convention, but as with the attribute names variants can be used at the cost of system legibility.
Python
In a python scripting context, everything is a variable pointing to some hidden data object. There's data in there somewhere, but python handles that automagically. There's a case to be made for Houdini managing all attribute data in the same way (automagically creating variables and managing attributes under the hood), and some Production Houses have built tools that kind of work this way (Pointastic anyone?). There's also an argument to be made for Houdini not second guessing or being smart for the user/TD though, and probably thats part of the reason why Houdini is widely preferred over some of it's competitors.
Thats it for SOPs as far as I know. Someone should add caveats for POPs.
Cheers
Houdini Lounge » LAIKA - Snr Houdini Effects TD
- tstex
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.
LAIKA R&D is looking for a senior Houdini effects TD:
http://apps.laika.com/jobs/detail/262 [apps.laika.com]
About LAIKA
http://recruiting.laika.com/ [recruiting.laika.com]
More LAIKA R&D jobs:
http://apps.laika.com/jobs/list?department=6 [apps.laika.com]
Senior Production Jobs:
http://apps.laika.com/jobs/list?department=19 [apps.laika.com]
.
LAIKA R&D is looking for a senior Houdini effects TD:
http://apps.laika.com/jobs/detail/262 [apps.laika.com]
About LAIKA
http://recruiting.laika.com/ [recruiting.laika.com]
More LAIKA R&D jobs:
http://apps.laika.com/jobs/list?department=6 [apps.laika.com]
Senior Production Jobs:
http://apps.laika.com/jobs/list?department=19 [apps.laika.com]
.
Houdini Lounge » Queue Poll
- tstex
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Rush here. Tested mantra on 100-200 cpus. Investigation of comprehensive RUSH/python/ROPs interface for managing Rush dependencies was favorable, (but not fully implemented or stress tested).
Race (Rush related) at DD is still the best system I've ever used. There was a grid engine based thing at a behemoth animation studio I worked at in L.A. that managed thousands of nodes ok, but the user interface was awful compared to race.
We looked at Temerity recently. That's more than just a renderfarm, but had some nice user interface tools for the renderfarm side of things.
Race (Rush related) at DD is still the best system I've ever used. There was a grid engine based thing at a behemoth animation studio I worked at in L.A. that managed thousands of nodes ok, but the user interface was awful compared to race.
We looked at Temerity recently. That's more than just a renderfarm, but had some nice user interface tools for the renderfarm side of things.
Technical Discussion » Another image sequence question.
- tstex
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Houdini Lounge » H8 to H9
- tstex
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The big problem bringing H8 files into H9 is lights cameras and rops. SOHO looks for very specific things, and the old objs/rops don't necessarily deliver them in the same way. Lights especially. Cameras less so, and rops less so again. Motion blur won't work for starters.
Everything else is pretty OK. There were a couple of default changes between H8 and H9 so watch out for an opscript -rb approach. Grid size default changed from 1 to 10 for instance.
In summary, it can be done, but there's a bit of clean-up work to be done afterwards. You don't want to be going back and forth that's for sure.
Cheers
Everything else is pretty OK. There were a couple of default changes between H8 and H9 so watch out for an opscript -rb approach. Grid size default changed from 1 to 10 for instance.
In summary, it can be done, but there's a bit of clean-up work to be done afterwards. You don't want to be going back and forth that's for sure.
Cheers
Technical Discussion » "Volume attributes" and fluid fields
- tstex
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Houdini Lounge » Creating a fake refraction/reflection shader in VOP's
- tstex
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Yep - I forgot to mention the front facing bit - Sorry!
(Dot products return a value from -1 to +1):
http://freespace.virgin.net/hugo.elias/routines/r_dot.htm [freespace.virgin.net]
Glad you got it working…
Cheers
(Dot products return a value from -1 to +1):
http://freespace.virgin.net/hugo.elias/routines/r_dot.htm [freespace.virgin.net]
Glad you got it working…
Cheers
Technical Discussion » NT_GeneratorThread::queueEvent eventqueuefull.Event dropped
- tstex
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Wow - you really want to avoid using software GL if possible. I'd suggest finding another fix if possible. What do you immediately before the error?
Houdini Lounge » Creating a fake refraction/reflection shader in VOP's
- tstex
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Have you looked at normalizing N and negated(I) from globals, and feeding them into opacity via some kind of fitrange function? That usually gives you the kind of opacity rolloff between front facing and perpendicular faces that I think you are looking for. (Alphapara/Alphaperp)
Another way of putting it (roughly):
1./ Normalize and negate I
2./ Normalize N
3./ feed them both into a dot product vop.
4./ put that into a fitrange or similar to tweak rolloff between 1 and 0.
Cheers
Another way of putting it (roughly):
1./ Normalize and negate I
2./ Normalize N
3./ feed them both into a dot product vop.
4./ put that into a fitrange or similar to tweak rolloff between 1 and 0.
Cheers
Technical Discussion » how to do an Recursive Comb Filter
- tstex
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I've attached a couple of things I did back in the days when I was doing this kind of thing.
I might dig up the Schwarzhild, Loucid and Heisenberg hipfiles and post them to the exchange one of these days. I'd be curious to see how they might look “remixed”. http://www.users.bigpond.com/tstex/music_vr.htm [users.bigpond.com]
Cheers
I might dig up the Schwarzhild, Loucid and Heisenberg hipfiles and post them to the exchange one of these days. I'd be curious to see how they might look “remixed”. http://www.users.bigpond.com/tstex/music_vr.htm [users.bigpond.com]
Cheers
Technical Discussion » how to do an Recursive Comb Filter
- tstex
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Houdini Lounge » Is H9 a better overall product than H8?
- tstex
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Houdini Lounge » Is H9 a better overall product than H8?
- tstex
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Phenom
Per request I would like to start a new thread and ask any and all Houdini Users if they would, as of now prefer working in H8.x, or H9.x
H9 - HOM, SOHO, UI, Fluids, Volumes. All big ++
Phenom
I have come to a compromise though. I will do my volumetric stuff in Maya, which is reliable and I can use with a certain amount of efficiency, and I will continue doing particle work in H8, which is also reliable and I can work with a certain amount of efficiency.
My verdict on H9 - it's a myth and it's been busted.
H9 isn't Maya. People should use what ever package they feel more comfortable in. I personally never used the viewport pre H9, so if there are bugs with the new workflows and UI they're not bothering me much.
Cheers
Technical Discussion » how to do an Recursive Comb Filter
- tstex
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HAH!!!
I can't tell you what that did in my head!!! It took me back to a wonderful wonderful place.
Good work - can't wait to see more…
Cheers
I can't tell you what that did in my head!!! It took me back to a wonderful wonderful place.
Good work - can't wait to see more…
Cheers
Technical Discussion » UVs on polygons, xyzdist bug?
- tstex
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The main suggestion I'd make is to start modeling with the connection edges so that you can guarantee the 1:1 match up of points to get a seamless join. I had a quick look at this new hipfile, and even if you could snap points to each other using an attribtransfer of P or whatever, you'll get all sorts of nasty pinching if your join edges don't match point for point. Getting an evenly divided circular sub-division from a grid is looking tricky at face value. Because you'd probably want to have grid prims hook up to the new circular connection points, it's touch and go whether you could do it without getting into the HDK. Someone may prove me wrong though.
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