I found a solution
I wrapped the output path with a hou.expandString() right before I return from the function.
Cheers
Rudy
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Technical Discussion » ROP output path expression
- rcortes
- 33 posts
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Technical Discussion » ROP output path expression
- rcortes
- 33 posts
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rafaels
Hey, Rudy
Have you tried putting the expression on the “pre-frame script” field and relative reference it in the output?
Might force the script to re-evaluate every frame…
Cheers
I thought about doing that, but I would really like to know the reason why the expression is not evaluated every frame and if there is a way to do so.
Cheers
Technical Discussion » ROP output path expression
- rcortes
- 33 posts
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Hi everyone
I have an expression in my ROP output path. The expression looks like this
footageOutput(“test”)
and returns something like this
/Volumes/Vault/Local_Users/rcortes/Desktop/test/test.$F4.exr
The problem im having is that when I render any frame, the expression always resolves to
/Volumes/Vault/Local_Users/rcortes/Desktop/test/test.0001.exr
However if i delete the channel so that the expresion output becomes the output path, it works just fine.
I think that for some reason, the expression is being evaluated at frame 1 and the result is being cached and used for all other frames.
Does anyone know how I can get this to work? Is there a flag to force an expression to evaluate on every frame? (I thought expressions did this by default).
Much obliged.
rcortes
I have an expression in my ROP output path. The expression looks like this
footageOutput(“test”)
and returns something like this
/Volumes/Vault/Local_Users/rcortes/Desktop/test/test.$F4.exr
The problem im having is that when I render any frame, the expression always resolves to
/Volumes/Vault/Local_Users/rcortes/Desktop/test/test.0001.exr
However if i delete the channel so that the expresion output becomes the output path, it works just fine.
I think that for some reason, the expression is being evaluated at frame 1 and the result is being cached and used for all other frames.
Does anyone know how I can get this to work? Is there a flag to force an expression to evaluate on every frame? (I thought expressions did this by default).
Much obliged.
rcortes
Technical Discussion » Dynamic bones
- rcortes
- 33 posts
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Its been a while since Ive been here and I need your help guys
Im setting up a rig where a number dynamic boxes are linked together with pin constraints to behave like a stick that is snapping (but not breaking)
I want to use the motion of the boxes as bones to deform my hero geometry. The problem im running into is that the motion from dops at the moment is point level, and what I need is an object transform to drive the objs that contain my capture regions.
Any idea how to extract/import transformation data from DOPs into an obj?
Cheers
Rudy
Im setting up a rig where a number dynamic boxes are linked together with pin constraints to behave like a stick that is snapping (but not breaking)
I want to use the motion of the boxes as bones to deform my hero geometry. The problem im running into is that the motion from dops at the moment is point level, and what I need is an object transform to drive the objs that contain my capture regions.
Any idea how to extract/import transformation data from DOPs into an obj?
Cheers
Rudy
Technical Discussion » Automatic Planar Reflections
- rcortes
- 33 posts
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Hopefully I'm not being thick icon_razz.gif - but by planar reflection map do you mean cubic reflection map? If so, look at the object you want the relfection on, Shading tab, and toggle on “Auto-Gen Reflection Map”, and set a location, name and size for the map. When it's done, mplay it - you'll find it contains 6 layers representing the six directions - you can use it directly as a CRM - no need to massage separate images.
Yeah, I saw those, bot that generates an EnvCube map. and it usually doesnt index properly for a flat surface. Im looking to generate a regular ol' reflection map. Which are usually the whole scene inverted, using the center of the flat surface as the pivot. That image is then indexed using NDC coords.
Thanks a lot for your help thoug
Cheers
Rudy
Technical Discussion » Automatic Planar Reflections
- rcortes
- 33 posts
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Is there a way to have houdini generate and use planar reflection maps automaticaly? I know how to do environment maps, but I cant figure out how to create and use planar maps.
Please help
RudyC
Please help
RudyC
Technical Discussion » Light Beams
- rcortes
- 33 posts
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Ok guys.. I found it..
I dont know how you used to do light beams on v.5, but to turn a light into a volumetric light you can create an atmosphere with the VEX lit Fog shader and you are ready to roll ( you might need to increase the density)
Light masks is what I needed for light linking.. thanks anyways guys!
Cheers
RCortes
I dont know how you used to do light beams on v.5, but to turn a light into a volumetric light you can create an atmosphere with the VEX lit Fog shader and you are ready to roll ( you might need to increase the density)
Light masks is what I needed for light linking.. thanks anyways guys!
Cheers
RCortes
Technical Discussion » Light Beams
- rcortes
- 33 posts
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Doug55
I am trying to render Light Beams in H6. Basically, I want the effect of a flashlight in a darkened and slightly foggy room. In H5 I used a cone light with a circular projection map in an environment permeated by uniform fog. To get the light to illuminate the fog, I went to the Atmosphere field in the Shading tab of the light to bring up the Light Beams dialogue box, set the characteristics of the fog, disabled ZMap Image, enabled Projection Map, accepted it all, and rendered. In H6, I cannot find an Atmosphere field in the light parameters. How do I access Light Beams in H6? If anyone can help with this issue I would be most appreciative, and thanks in advance.
I ALSO NEED THIS.. I need to generate volumetric lights. could some one please post a simple solution. Im sure that once I get the basics I can take it from there.
I also need to know how you do light linking so that I get to choose which objects are affected by which lights..
Thanks in advance
Rcortes
Technical Discussion » Inserting RIB commands
- rcortes
- 33 posts
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Arrrgg!!… there it was .. all the time!!.. thanks so much…
Got to go… there are things to render!.
Cheers
RCortes
Got to go… there are things to render!.
Cheers
RCortes
Technical Discussion » Inserting RIB commands
- rcortes
- 33 posts
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Is there a way to pass specific RIB commands to my RenderMan renderer? Something like MtoR's RIB box would be great, where I can just type in the commands and then declare whether it will be inside the Attribute description of an object, or at frame begin or world begin?.
Thanks a lot
RCortes
Thanks a lot
RCortes
Technical Discussion » rmands dialog editing
- rcortes
- 33 posts
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That worked perfectly!!!.
Once again you guys from xyz come out to my rescue.. Thanks so much for your help.
cheers
Rcortes
Once again you guys from xyz come out to my rescue.. Thanks so much for your help.
cheers
Rcortes
Technical Discussion » rmands dialog editing
- rcortes
- 33 posts
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Hello there… Im having some problems with rmands. When i run it with
rmands -d dsomewhere -L myrmanshads.olt myshaders.slo
I get the right dialog.. the only problem is when I load the otl some of the parameters come in with a type I dont like… for instance most of my strings come up as a file type parameter . This is not terribly bad , but I would like to edit the dialog so that I can turn some of these strings into drop down choice menus, check boxes (for booleans) and things like that (I really like how I can do this for vex shaders). but when I edit the otl file it gets ruined… (houdini wont load it anymore)
I could also do the dialogs with *.ds, but the scripting documentation refers to what I believe is an older file strucutre used in 5.0, I cant find the files or folders they tell me to use to have houdini load my *.ds automatically.
Can someone please help.. Thanks
cheers
Rcortes
rmands -d dsomewhere -L myrmanshads.olt myshaders.slo
I get the right dialog.. the only problem is when I load the otl some of the parameters come in with a type I dont like… for instance most of my strings come up as a file type parameter . This is not terribly bad , but I would like to edit the dialog so that I can turn some of these strings into drop down choice menus, check boxes (for booleans) and things like that (I really like how I can do this for vex shaders). but when I edit the otl file it gets ruined… (houdini wont load it anymore)
I could also do the dialogs with *.ds, but the scripting documentation refers to what I believe is an older file strucutre used in 5.0, I cant find the files or folders they tell me to use to have houdini load my *.ds automatically.
Can someone please help.. Thanks
cheers
Rcortes
Technical Discussion » VEX shading question
- rcortes
- 33 posts
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Mario MarengoMichaelC
I've run into the same problem, and Du(s), Du(t) do not work.
If you meant Du(s), Dv(t) (instead of Du(t) ), then I believe it *should* work.
Here's how I understand it:
PRMan: dPdu -> VEX: (dPds/Du(s))
PRMan: dPdv -> VEX: (dPdt/Dv(t))
PRMan: du -> VEX: Du(s)
PRMan: dv -> VEX: Dv(t)
And the reason is that in VEX, dPds has already been scaled by what in PRMan would be “du” (and simmilarly, dPdv is pre-scaled by dv), thereby saving you from having to type “dPdu*du” or “dPdv*dv”, which is arguably the more frequent usage of these things…
Thanks… now I know its my shader and not a bad use of the Du(), Dv() functions..
Technical Discussion » VEX shading question
- rcortes
- 33 posts
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edward
See $HH/vex/include/prman.h
HI Edward! hows everything?
I did take a look at prman.h and I cant find any declaration macro for du or dv.. the closest I find is dPdu and dPdv and according to the Ri Spec 3.2 those 2 are “Derivitive of surface position along u or v” and what I need is the “Change in surface parameters” which is du, dv.
so the macros
#define dPdu (dPds/Du(s))
#define dPdv (dPdt/Dv(t))
are not really providing me with what I need
cheers
Rcortes
Technical Discussion » otl OP type
- rcortes
- 33 posts
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Hello there.
Im trying to put together an otl that will behave like a simple cluster. The problem Im running into is that at the object level I can only make otl's as subnetwork. This means that my capture region sop is under 2 levels of objects and when I create several as children of a null (like you do with bones) and apply that hierarchy to the deform sop on my mesh,the deform cant find the capture regions.
Basically what I need to make is something like the built-in bones. An object level with a direct 1st level sop network where I can place my capture region.
thanks a lot
RC
Im trying to put together an otl that will behave like a simple cluster. The problem Im running into is that at the object level I can only make otl's as subnetwork. This means that my capture region sop is under 2 levels of objects and when I create several as children of a null (like you do with bones) and apply that hierarchy to the deform sop on my mesh,the deform cant find the capture regions.
Basically what I need to make is something like the built-in bones. An object level with a direct 1st level sop network where I can place my capture region.
thanks a lot
RC
Technical Discussion » VEX shading question
- rcortes
- 33 posts
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Hello there… i've got a simple question that Im sure you guys will be able to answer.
Im converting some RenderMan shaders to VEX and I cant find a global variable to resemble RMan's "du and dv“. Do I use
” Du(s) and Dv(t)" to get those values?. I need this for anti-aliasing my shaders. They are REALLY aliasing right now.
Thanks a lot
RCortes
Im converting some RenderMan shaders to VEX and I cant find a global variable to resemble RMan's "du and dv“. Do I use
” Du(s) and Dv(t)" to get those values?. I need this for anti-aliasing my shaders. They are REALLY aliasing right now.
Thanks a lot
RCortes
Technical Discussion » character modelling!!!!
- rcortes
- 33 posts
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I dont know how much experience you have with 3d modeling. If your experience is limited I would encourage you to model something that you can get a lot of reference images (cat, dog, tiger). If you go for a dragon you will have to use your imagination, knowledge of anatomy or some conceptual drawings and for someone who doesnt have the training this could be a very frustrating task.
The multi-patch dragon tut on highend3d is pretty good, but nurbs patch modeling is quite different from Maya to Houdini.
I think your best bet is to model simpler objects that you can get your hands on (non-living objects arround your house) untill you have really mastered your modeling tools, whether they are nurbs or polys. Then move into more complicated organic stuff that you can get reference images of(people,animals) adn then move to the fantasy arena. I know this sounds like a long road and it is, but you will be training your eye, you feeling for an object's volume and your modeling speed.
Take care and good luck
RC
The multi-patch dragon tut on highend3d is pretty good, but nurbs patch modeling is quite different from Maya to Houdini.
I think your best bet is to model simpler objects that you can get your hands on (non-living objects arround your house) untill you have really mastered your modeling tools, whether they are nurbs or polys. Then move into more complicated organic stuff that you can get reference images of(people,animals) adn then move to the fantasy arena. I know this sounds like a long road and it is, but you will be training your eye, you feeling for an object's volume and your modeling speed.
Take care and good luck
RC
Technical Discussion » !RENDERMAN HELP!
- rcortes
- 33 posts
- Offline
ok.. it seems that your are kind of new to houdini and renderman (dont be offended if you are not). I will give you some pointers that might help you on the future.
1 - Rib shaders… no such thing. RIB stands for RenderMan Interface Bytestream. It is an easier, more compact way to access the Ri API. The Ri API is what describes your scene (models, lights, shaders, camera view). Renderman shaders are written in RenderMan Shading Language (RSL or SL). People refer to them as RenderMan shaders.
2- when you apply a RMan shader to geometry in Houdini you will NOT get visual feedback of that PRMan shader until you render. Real time visual feedback its usually handled by OpenGl, and at the moment Houdini doesnt offer a way to visualize RMan shaders real time (someone correct me if im wrong)
3- if some shaders work and others dont, then its most likely that PRMan is not finding the missing shaders. Make sure they are compiled and included in the shaders folder. You can also include a shader search “Option” inside the RIB file, but at the moment I cant remember how you can have Houdini insert RIB statements before it renders. Please read you PRman user Docs, it should explain how to setup paths for shaders and how to use “Options”
I believe Ian Stephenson did a little houdini how-to.. you can read it here
http://www.dctsystems.co.uk/Houdini/index.html [dctsystems.co.uk]
and here
http://www.dctsystems.co.uk/Houdini/hKickstartPrman.html [dctsystems.co.uk]
another one
http://home.earthlink.net/~mdcronin1/PRMan.htm [home.earthlink.net]
good luck
rcortes
1 - Rib shaders… no such thing. RIB stands for RenderMan Interface Bytestream. It is an easier, more compact way to access the Ri API. The Ri API is what describes your scene (models, lights, shaders, camera view). Renderman shaders are written in RenderMan Shading Language (RSL or SL). People refer to them as RenderMan shaders.
2- when you apply a RMan shader to geometry in Houdini you will NOT get visual feedback of that PRMan shader until you render. Real time visual feedback its usually handled by OpenGl, and at the moment Houdini doesnt offer a way to visualize RMan shaders real time (someone correct me if im wrong)
3- if some shaders work and others dont, then its most likely that PRMan is not finding the missing shaders. Make sure they are compiled and included in the shaders folder. You can also include a shader search “Option” inside the RIB file, but at the moment I cant remember how you can have Houdini insert RIB statements before it renders. Please read you PRman user Docs, it should explain how to setup paths for shaders and how to use “Options”
I believe Ian Stephenson did a little houdini how-to.. you can read it here
http://www.dctsystems.co.uk/Houdini/index.html [dctsystems.co.uk]
and here
http://www.dctsystems.co.uk/Houdini/hKickstartPrman.html [dctsystems.co.uk]
another one
http://home.earthlink.net/~mdcronin1/PRMan.htm [home.earthlink.net]
good luck
rcortes
Technical Discussion » multilayered vex shader
- rcortes
- 33 posts
- Offline
I had figured it out already, but as usually you are right John C. That is exactly what I did..
got to go now… I got shaders to write.
cheers
rcortes
got to go now… I got shaders to write.
cheers
rcortes
Technical Discussion » multilayered vex shader
- rcortes
- 33 posts
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That sounds good, but i think i didnt get m point across right.. sorry about that..
what I need to do is use a DIFERENT uv projection or coordinates for each of the layers, for instance to add a very detailed tatoo on a character that already has a base layer uv.
My question still remains “ how do I make my shader read the UV coords from layer a, b,c,…etc. ”?
Thanks a lot.. it was still very helpfull
Cheers
RCortes
what I need to do is use a DIFERENT uv projection or coordinates for each of the layers, for instance to add a very detailed tatoo on a character that already has a base layer uv.
My question still remains “ how do I make my shader read the UV coords from layer a, b,c,…etc. ”?
Thanks a lot.. it was still very helpfull
Cheers
RCortes
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