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Technical Discussion » Launching hrender from python script in Houdini
- NFX
- 183 posts
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So I have a custom node I have made that has a button that when pressed, I would like to launch a render on my machine using the hrender command. Unfortunately I haven't been able to figure out how this is supposed to be done from within a python script. Any tips?
Technical Discussion » How to launch a WREN render from the command line
- NFX
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The title says it all. I am trying to implement WREN support on our farm and am having trouble finding the proper command for launching it. Can anyone enlighten me?
Technical Discussion » How to node with the render flag from a copnet?
- NFX
- 183 posts
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Not that I've been able to find. It seems like copnets are kind of the ugly stepchild when it comes to code. Lots of things either work very differently from everywhere else in Houdini or aren't implemented at all. Makes me wonder if a future overhaul is planned.
Technical Discussion » How to node with the render flag from a copnet?
- NFX
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tamteDrat. I was hoping there would be a method that wouldn't require iterating over all the nodes. Thanks for the code though.def getRenderNode(subnet): for node in subnet.children(): if node.isRenderFlagSet(): return node
Technical Discussion » How to node with the render flag from a copnet?
- NFX
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Using Python, is there a way to select the node with the render flag set from a copnet?
Technical Discussion » How to bake out vector displacement map
- NFX
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I've been trying to figure out how to bake high-res geo as a vector displacement map for a lower-res cage. Despite following Sidefx's masterclass for baking out tangent normal maps, I can't seem to figure out how to render the low-res mesh with the baked map properly. Using the mantra surface shader, I have tried setting up the vector displacement tab several different ways but the end result always looks significantly different than the high res geometry. Is there a step that I am missing?
Technical Discussion » Meshing FLIP with airfield
- NFX
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I have been playing around with airfields and looking into ways to mesh the resulting water sim and was wondering if anyone on the forum has found a solution to this? I've had a couple ideas such as creating two separate surface volumes or perhaps having two completely separate FLIP sims interact with each other but so far haven't been able to get either approach to work. Anyone want to share some ideas?
Technical Discussion » Custom VEX functions
- NFX
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Technical Discussion » Custom VEX functions
- NFX
- 183 posts
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So I find that I have things I write regularly in my wrangle nodes (pcimport functions with a custom weight function for example) and was wondering if there is an easy way to save them to a file or something so that I don't have to keep retyping them? A quick search online seems to suggest that I would need to do this in HDK, but I am hoping there is a faster way.
Technical Discussion » Dripping in POPs
- NFX
- 183 posts
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Gotcha. I was considering that option, although I think I will try to implement something in POPs first before heading down that route since in the long run having a full particle solution would be convenient. Thanks for the idea though.
Technical Discussion » Dripping in POPs
- NFX
- 183 posts
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While I understand how I could use curves or creep to make drips that stick to the wall, I don't know how that would solve the trickle merging issue which is what I am trying to solve. Basically I need to find a procedural way to make it appear that the trickles are drawn towards each other and then merge on contact rather than just flying past like the current attract pop does.
Technical Discussion » Dripping in POPs
- NFX
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So I have been working on creating a blood splatter tool and am stuck on how to get realistic looking dribbles on the wall like in this video…
https://www.youtube.com/watch?v=c2v404Lxc8c&list=PL2Onw7I36aWj11IdMMz_OrfFXUcj0aa5S&index=1 [youtube.com]
While I can get 90% of the way there on my own, the part that is stumping me is how to implement particle attraction so that the streams are drawn together and flow into one another. While I suppose I could delete a dribble particle once it finds another dribble, I would prefer to constrain it to the other's path until it either reaches the end or gathers enough momentum to break free. Any ideas here would be super helpful.
https://www.youtube.com/watch?v=c2v404Lxc8c&list=PL2Onw7I36aWj11IdMMz_OrfFXUcj0aa5S&index=1 [youtube.com]
While I can get 90% of the way there on my own, the part that is stumping me is how to implement particle attraction so that the streams are drawn together and flow into one another. While I suppose I could delete a dribble particle once it finds another dribble, I would prefer to constrain it to the other's path until it either reaches the end or gathers enough momentum to break free. Any ideas here would be super helpful.
Technical Discussion » Lighting flickering
- NFX
- 183 posts
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So I am rendering a scene lit by a HDRI map and rendered on a farm. When I get the shots back there is a subtle flickering along with a bright flash every now and then. I think this may be somehow related to my environment light or sampling, but really have no clue. Any ideas?
Technical Discussion » Creating a slow river with FLIP
- NFX
- 183 posts
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Thanks for all the tips. After digging around in your file, Solitude, I was able to set up a system that generates the rest fields in the same simulation as the flip and seems to work pretty well for what I need. Thanks for demystifying the process with that file!
One last question I have is tips for how to shade the water and foam so that it feels like a largish river. Right now I am finding that my water either ends up feeling “thick” or too clear. Any shader tricks that help sell scale?
One last question I have is tips for how to shade the water and foam so that it feels like a largish river. Right now I am finding that my water either ends up feeling “thick” or too clear. Any shader tricks that help sell scale?
Technical Discussion » Creating a slow river with FLIP
- NFX
- 183 posts
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Oh, thanks I seemed to have missed the link on my first read through. Great example file by the way.
Technical Discussion » Creating a slow river with FLIP
- NFX
- 183 posts
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So after some tweaking and adding more collision geometry to the river bed it is starting to look a lot better. Thanks for your advice.
I have been considering using an advected texture or rest position to add some smaller noise to the surface of the water but haven't done anything like this before. Any tips on how to do the dual restfield or dual uvs method? Thanks!
I have been considering using an advected texture or rest position to add some smaller noise to the surface of the water but haven't done anything like this before. Any tips on how to do the dual restfield or dual uvs method? Thanks!
Technical Discussion » Creating a slow river with FLIP
- NFX
- 183 posts
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So here is the look I am going for. Notice lots of fine surface detail mixed with churning and whitewater that happens when you are near rocks.
https://upload.wikimedia.org/wikipedia/commons/4/44/Thredbo-River_Crackenback_rocks.jpg [upload.wikimedia.org]
Attached is what I am currently getting. Notice it is boiling far too much and lacks fine detail in larger areas.
https://upload.wikimedia.org/wikipedia/commons/4/44/Thredbo-River_Crackenback_rocks.jpg [upload.wikimedia.org]
Attached is what I am currently getting. Notice it is boiling far too much and lacks fine detail in larger areas.
Technical Discussion » Creating a slow river with FLIP
- NFX
- 183 posts
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So I am working on a project that has a somewhat large flat river with some whitewater and churning where it meets clusters of rocks but otherwise needs to be pretty flat with some nice small scale surface detail (the new jungle book movie has a similar look in this way). After several tests I keep getting something that is too “billowy” or roaring rapids and that lacks fine surface detail. I am almost wondering if FLIP is the best way to approach this. Any ideas?
Technical Discussion » Vector VBDs in Volume Vop
- NFX
- 183 posts
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So I have been doing some work with custom velocity volumes and have been puzzling over a few things. For instance, the volume vop allows me to bind and iterate over vector volumes, but I can't seem to figure out how to tell which volume it is processing. Is there a way to tell which primitive the current voxel belongs to?
Another thing I have had trouble with is finding the proper way to combine vector vdbs. No matter what I do it complains that one of the inputs has move volumes than the other.
Finally I am a little confused about how to properly create and initialize scalar and vector vdbs. Any tips?
Thanks!
Another thing I have had trouble with is finding the proper way to combine vector vdbs. No matter what I do it complains that one of the inputs has move volumes than the other.
Finally I am a little confused about how to properly create and initialize scalar and vector vdbs. Any tips?
Thanks!
Technical Discussion » Black line on baked texture
- NFX
- 183 posts
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Thanks for the reply. I ended just using rops to expand the boundries. It would be nice if houdini did this on rendering though…
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