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Found 13 results

  1. i have little problem with randomizing material with instancing , i have a tree that has 2 materials 1 for bark and 1 for leaf the problem is to randomize a material with instancing is to apply the material after instancing and if i have multiple materials for each group or if i have multi geo with different materials and sub materials it will be a huge complex to randomize the materials and assigning them , i already tried material stylesheets but i failed to make it work , my main goal is to assign the materials for objects before instancing them. in 3ds max vray there is a node called vray multisub tex and there is forest color i can apply them materials and sub materials to make sure to have different color per element per instance so i dont have to assign the materials after instancing i need only to assign the materials for objects before instancing . im trying to achieve the same thing in houdini in in this pic i have select_attribute i want to randomize it to have random number per instance if anyone can help me using material stylesheets and thank you. random tree leaf before instancing.hipnc EDIT: my idea is to have random value per element and per instance and most importantly to apply the materials before instancing and packing in case i have multi objects (buildings ,trees ) or in case i have multi material per object (tree: leaves and bark, or building : windows , walls, roof), i dont think this is possible to do without material stylesheets
  2. Hi! Is there a way to get the name of rendering object in CVEX with Volume Procedural? Like this is done using renderstate? I want to use one CVEX for some objects and change filename parameter in it depending on the object. Now I use shared CVEX from Vopnet with Filename parameter on it, but it have some limitations for me.
  3. Hi, This is Nandan from SPin Vfx. I am working on Material Style sheets in Houdini 16.5. I want to add add subdivision groups under Render Polygon as Subdivision (Mantra) on the rendering geo. I see I can create a Render Property override on the geo in the style sheet and set it to one. To specify the groups for subdivision (which is also a render property on the geo) I wanted to write an inline script in cvex to return an array of string to fill the subdivision parameter. My question is: 1) Can that be possible? Can I return a string from cvex and populate the subdivision group parm on the geo using style sheets. I do not want to hard code it, I want to return it from cvex 2) Should I be returning an Array of Strings from the cvex funtion, if there is more than a single group. 3) Can I get any reference to working example? Any help will be much appreciated.
  4. I wrote a lens shader in CVEX that is supposed to get some data from geo level (ie. a position to look at). Unfortunately no full path expression on my shader node does seem to work: detail("op:/obj/mesh/OUT"), "center", 0)
  5. Hi, Is there an possibility to have @ working to create write attributes in a vex function? Something similar to the following function void test() { i@test_attrib = 10; } The reason I want to avoid setattrib is that it is much slower as implementation. Are there any other idea's? does the *.vcc compiler optimize the setting of attributes? Cheers
  6. Hi Guys If anyone has done this and has a solution or any advice that would be great and hugely appreciated. It is fairly easy to do all of this if your volumes to instance are within your hip scene. However once you are only referencing them from disk I am struggling to run the cvex over each instanced volume (of which I am using 20 different variations hence using the "instancefile" attr.) I am also trying to volume sample each instance to pull in surface, rest etc primitives into the cvex context to drive my displacement. many thanks tom
  7. Hi, Does anyone the how I to access the input geometry from a custom VEX function. I know I can use the path of the node as an argument and get the input geometry, but is there anyway to create a VEX function that can access the current geometry? For example, I have a pointwrangle node and I create an attribute, then I call my custom VEX function, how can I get access to that geometry? Or would that have to be handled by something like a VEX_GeoCommand and it's only possible to access the input geo from the HDK? Thanks, Tom
  8. The past month I've been working on the shot with very long rocket trails, so I developed a CVEX shader to avoid smoke simulation. The shader uses information from particles to generate volume with specified shape and requires much less memory.
  9. Hey Guys, I finished this project a while back. I included it in my showreel just before the FMX. If you want to see breakdowns of the scene, it's in my showreel. I also show the diversity of the shader used. The Breakdown starts at 00:40. In the bottom video you can see the WIP too. Everything but comp is Houdini. Mountain range is completely procedural. The Shader is procedural, snow amount is slope and height dependent mixed in with noise, you can determine the snow / rock bias too. The rocks under the snow is in the same shader and is controllable by reflection and displacement amount. There are three smoke sims on the left, top and right of the shot. The top one is a clustered pyro sim. In the top sim I used the velocity field to advect some particles for the snow effect. In the background the clouds are VEX Volume procedurally generated.
  10. I am using a vex volume procedural shader, connected to a new cvex operator to generate a volume starting from points at render time. In the cvex op, I use pcopen to open a point cloud, then I process those points and export "density" and "Cd". Everything works great (even if the render time is insane ..). Now I'd like to export additional image planes. For instance I added an "export float nage ..." (normalized age of the points) and added a new float image plane to the Mantra rop, but the render of that image plane always comes out black. I tried to set nage = 1 by default to make sure it really doesn't work. My questions are: 1 - I noticed that I can successfully export "density" and "Cd" from the cvex operator to the vex volume procedural. Are there additional Mantra parameters vex volume procedural accepts from the cvex op ? 2 - what is the proper way to render new image planes using the previous setup ? For instance exporting Ce connected to a remapped density to simulate heat. Please let me know if the question is not clear enough and I'll setup a small hip file to illustrate the issue.
  11. Hi, Probably an obscure question... I am using the VEX Volume Procedural. It is working nicely but in the docs it states: The following inputs parameters are available in the CVEX context used by the VEX Volume Procedural: - P Position to evaluate, in object space. Now I would actually like to get the world space position. It seems not that important but in my case I would to instance several (procedural holders) pointing to the same geometry shader and cvex shader. Like I said, obscure question but it doesn't hurt to ask right? Cheers, Rog.
  12. Hi there, this is my first at forum, so big thanks to any feedback anyway. I built simple standalone program using HDK and GU_Fur class (that if I understood just a C++ wrapper around Fur SOP and Fur mantra Procedural). You can find it at GU_Fur.h. Everything worked great, i can pass any surface geometry, change "Fur SOP" parameters and, get fur geometry very easily. I can guess this way we can build things like Renderman Fur DSO or other renderers DSO's at no time. Except one fact: i cannot find a way how we can pass cvex guide shader and skin shaders to our SOP wrapper. Its excepts UT_String, but since there is not docs about it at all, and I can only just try things. I can guess that this wrapper only work in Houdini GUI or mantra environment and can access shaders only using "op:$shoppath $params" syntax, because that thing spits warning "Cannot load guideshader" if i pass something to it this way. That also happens if pass shader code (trying both source and compiled) to it. BUT! if pass shader path to existing compiled vex file, there is no warnings at all! But my little piece of software crashes when i call generate method! I dont know if its due to my vex shader ( I doing simple example with sphere and get shader code from FUR OBJ native to Houdini), or I doing something wrong, or it is some Houdini bug (I working with latest stable build). Any suggestions, or idea is appreciated.
  13. Hi everyone, I was wondering if it is possible to "polywire" a set of curves at render time using cvex. I tried to use the fur procedural shader, I have a simple cvex shader for the guides, with just a parameter for width. And it renders nothing. Do I have to fill in every parameters of the fur procedural ? ( i am pretty sure it's not a good approach ... ) Or is there a simpler set up to do that ?
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