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DanFor

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Everything posted by DanFor

  1. Hi, How would one go about varying one parameter on one of the shaders on an object being instanced that has multiple materials applied in its geo network? I have watched a few tutorials and read some posts on instancing and varying material / shader parameters. However, all of them deal with simple objects and varying the material parameter applied to object at scene level (or using point attributes, which again set the material for the entire instance). Varying for example the color for the material being applied to an entire instanced object is easy (using pointinstance() to drive it), but using pointinstance on a material parameter, when the material is applied in a sop network affect all instances in the same way, there is no variance. I hope my case description makes sense. Any pointers would be very welcome. Thanks in advance! Dan
  2. Heightfield mask into comp?

    Thanks! I dug around a bit, and my problem turned out to be my confusion regarding how Houdini handles two things: - The comp / over nodes and default alpha behaviour - Houdini's apparent inconsistency when displaying mask images. I will explain: When looking at the my mask (the image from the sop import) the comp view displays it as black->red. However, the thumbnails in the tree view are in greyscale. This threw me for a loop and I thought I had missed some colourspace conversion step. In the end it turned out I basically had things right, but to get the proper values I had to use a channel copy to properly bind the reds in the imported mask into mask values. So, sorry for the ignorance and many thanks for the help. I hope this might be of help to someone else in the future.
  3. Hi, I am trying to pull height field masks from a terrain geo into a composition (to build a diffuse map as a terrain base texture), basically following the workflow in the youtube video below. However, one thing has me stumped. Getting masks from the height field into a comp is straightforward (sop import node). However, when I set the sop import comp node to generate the custom planes (to get the mask and other geo data), the images generated are red/grey instead of grey scale. In the youtube video he does not seem to have that problem (although he skims through those parts extremely quickly, around 27 minutes in). Am I missing some additional step to get height field mask data to work as a simple greyscale mask in a composition...? Many thanks in advance for any pointers!
  4. Heightfield mask into comp?

    Thanks! I still get the red mask image interpretation though. It is as if the imported planes are coloured. However, the thumbnails are greyscale...? And in the composite node, I can see that the mask applied is indeed the coloured one I see in the image viewer, as areas that are supposed to be masked (with the correct mask interpretation) are bleeding through. Any ideas? As much as I love Houdini for its powerful procedural approach, I must say I really dislike the lack of documentation and myriad of quirks all over the place...
  5. Heightfield mask into comp?

    I should perhaps clarify. The image in the sopimport 2 thumbnail is what I want and expect. However, when applied as a mask to the over node, the result is not as expected. And this is why. When looking ahh the sopimport2 mask channel, it actually looks like this: ...and I cannot seem to find any option to make sure it is interpreted as a suitable mask greyscale.... :-/ Again, many thanks for any advice!
  6. Distortion VEX Question...?

    Ah - I see. So the displacement bounds will cause the clipping as the bounds need to encompass *any* geometry (even though the resulting geometry may itself be undisplaced). Makes sense. Maximum displacement though is a bit illogical, or needs better documentation. As someone coming from other packages, I was expecting that to scale my input values (as the multconst does in your setup). Clearly that is not the case. Anyway, many thanks for explaining the concepts and helping me get to a point where I can continue to build the network! Much appreciated.
  7. Hi, I am trying to build a simple shader using the principled shader and unified noise. However, I must be missing something. The simple network is rigged as in the picture. So restpos -> unified noise -> vector displacement input under "other" in the principled shader. I do get displacements, but the "maximum displacement" slider is not doing what I would expect it to. Setting maximum displacement to 0, does not get me the original geometry. I would have thought the max displacement parameter dictated how much displacement to apply, where zero would be "do not distort the geometry"? I have input distortions enabled. FWIW I cannot find this properly documented anywhere and even as a 30 year veteran of CGI it is not clear to me how some of the VEX nodes are intended to operate. Any advice would be greatly appreciated!
  8. Distortion VEX Question...?

    So...in my quest to understand this, I have noticed the following (with the same network setup as earlier, piped to disp): - Setting displacement bound and/or max displacement to zero with non-zero input from noise (1D) = crumpled sphere - Having displacement bound and max displacement be 1 or other sane non-zero value, multiplying the 1D noise with 0 = original, non-displaced sphere. So, the displacement controls on the principled shader appear to be useless for fine adjustments of the displacement effect. That has to be done by multiplying the input. Whether that is a bug or by design (and me failing to grasp the concepts) is still unclear to me.
  9. Distortion VEX Question...?

    EDIT: Never mind this. It was due to displacements not updating without toggling them on/off. I just downloaded your example, and it too has a problem: Regardless of what I adjust, I cannot get the displacements to fade to zero without disabling them. Setting max displacements and/or bounds to 0 still yields displacement. As does adjusting the constant to 0. I still get displacement, even though (IMHO) there should be none...? I must admit I feel quite confused at the moment.
  10. Distortion VEX Question...?

    Thanks for the reply! Well, for what it is worth I tried most combinations of vdisp/disp as well as different displacement spaces (uv, object space), etc. Please take a look at the two images enclosed. The second pic depicts a sphere being deformed with a positive displacement value. Sort of looks as expected. The first picture is with max displacement set to zero, which results in a crumpled and severely distorted sphere. Worth noting is that the displacement bounds (which I am not entirely sure what it does, have to read up) is automatically linked to the max displacement value. How or why that happens I am not sure, but I am not linking that parameter manually... So, I still feel uncertain whether it's me doing something wrong or the functionality being broken...?
  11. DOPnet transform Q?

    Thanks for the reply! I would really like to keep the sim networks at least one level down (in their respective geo nodes) to keep the project from getting cluttered. However, I now have them on scene level and can't seem to move them into a geo node... Any idea how to achieve that? (As mentioned, I can't get cut/paste to work...). Regarding the transform issues it appears to be a common issue and it's quite easy to test: 1. Quickly create a cloth object with the shelf tools. 2. Move the geo node around, drop into dop level = no problem, scene view as expected. 3. Create a subnet containing the geo and dop nodes. 4. Head down into the subnet and into the dop nodes = the simulated object shifts position. Which is a bit strange...
  12. Hi, Currently transitioning to Houdini, and I would really appreciate if some kind soul would help me by explaining the following: How does a Houdini DOP network deal with nested transforms? I am currently simulating a sail using cloth. It works quite well, but I have noticed that if I move the sail geometry (by transforming the geometry node or the bundle containing it), the dopnet seems to ignore these transforms. This is visible since when stepping into the DOPnet, the dynamic object will shift in view. So, I am currently confused regarding the right way to set up and transform a system that will be dependent on outside objects (in this case, the mast and rigging that will be moving), Any explanation or advice would be most welcome. Many thanks in advance!
  13. No Shader View...?

    Ah... I see. Thanks!
  14. Hi, Is the Shader View pane gone in 16.5? I see references to it in the docs, but cannot for the life of me find it in the UI? Asked the Q in the SideFX forums, but got no reply despite a very basic question. Do SideFx participate there, anyone know? Thanks in advance! Dan
  15. DOPnet transform Q?

    ..and I found some older posts where the conclusion seemed to be: Don't put sims in subnets. Which prompts two follow-up questions: - If I have a more complex scene with multiple simulations, how do I keep it organised on a scene level? I do not really want a bunch of separate dopnets on scene level. - One solution I have seen in tutorials is to actually create the dopnet in the geo node (besides all the modelling stuff): 1. Is this recommended? 2. If so, how can I move an existing dopnet into a geo node? Copy/paste does not seem to work... Again, many thanks for any help!
  16. DOPnet transform Q?

    Just to add my first findings: - It seems that having a subnet with a geo node and a dopnet, and transforming the entire subnet will throw off the dopnet. Ie, it ignores the subnet world pos?
  17. Ok - as expected it was simple: The referenced object needs to be added to the sim using a StaticObject node. The OBJ Path needs to be set to the animated object. This can then be used as a constraint reference in the usual way. However, I am surprised this was not covered in any tutorial I watched, since directed simulation is something that is very common (IMHO). Anyway, hope this helps someone else.
  18. Hi, Recent convert to Houdini, and I have what I assume is a very basic question: If I have a DOP set up for a cloth simulation, and want to constrain points on the cloth to an external (other top level geometry) animated object, how can I reference this object and its various points from the DOP (which is in another geo hierarchy)? I have played around with SOP Import nodes and other things in the DOP network, but while I can reference my animated geometry with these I cannot seem to pipe any useful information to (for example) a sbdpinconstraint? Apologies for the ignorance, but I have searched for a tutorial or explanation for a couple of hours... Thanks in advance!
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