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Jesper Rahlff

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Everything posted by Jesper Rahlff

  1. Earth atmosphere with Redshift (or finding the "ANY" KEY)

    I cannot share a simple example of this because I am at work right now, so you will have to test it your self. But I am pretty positive this will work
  2. Earth atmosphere with Redshift (or finding the "ANY" KEY)

    My understanding is that because the VDB is a sparse volume if you do the subtraction of the earth geo from the atmos volume and then use a VDB activate node it will deactivate the voxels which has a value of 0 hence not storing that data. You can visualize that with the VDB Visualize Tree node.
  3. Earth atmosphere with Redshift (or finding the "ANY" KEY)

    can you not just convert the earth geo to a volume and subtract that from the atmos volume leaving you with only the visible atmos?
  4. I just use CTRL + X to cut the node. keep doing that and you overwrite your cut history essentially removing the node
  5. vellum and FLIP feedback force (floating vellum)

    how about using a proxy SDF volume as your collision object for Vellum?
  6. Try using chs() specifying that the input value is a string.
  7. reset to origin.

    Hello Odforce! I often find myself in a situation wanting to take each piece of geo I have from an alembic, move it to the origin and "reset" rotation for convinience, do some operations, and then move it back to its original place with its original rotation on it. However I often find my knowledge short to do this stuff. I have crafted an example file here of my problem and hopefully some of you can help me with a few examples on how to do this. As described in the file, this is what I want to do: - move each piece of geo to the origin. - calculate the rotation thats on the piece of geo, and "reset" it so that the point with @Cd = {1,0,0} is upwards. - put the geometry back to its original position with its original rotation. I hope you guys can help fill the gap I have when it comes to this kind of stuff. Cheers calculate_transform.hiplc
  8. overwrite default state based on parameter on HDA

    here is a screenshot. I created an empty subnet, converted it to an HDA. The parameter on the HDA which is circled red here is the one I want to override. This parameter is available on an HDA by default. its not related to anything going on inside the subnet
  9. Hey Peeps. Not sure which category this questions belongs to so I threw it into the general question forum. I am currently building an HDA with one of the functions of this HDA is to draw curves. In order for me to be able to draw the curve on the top level of the HDA with the drawcurve tool I have to set the default state of the HDA to 'Stroke'. This is all working fine. My issue is now that because the HDA is holding more than one "Mode" I only want the default state to be 'Stroke' when the mode is set to utilize the draw curve function. In other words, I only want the interactive draw tool in the viewport to be active when a certain parameter is active. I hope I explained this well enough, if not let me know and I will try to be more visual with a simple example file (at work currently so cannot share anyting). Thank you in advance. Cheers
  10. overwrite default state based on parameter on HDA

    No one?
  11. Houdini engine smoke

    you are welcome. let me know if anything is unclear
  12. Houdini engine smoke

    attached is a simple example of how I would set it up to get ultimate control over resolution of your volume without having to sim a billion points. OdForceVolumeQuality_suggestion.hipnc
  13. you should just use one shader and then each of your petals should have an unique id attrib that defines who they are. You can then name your map albedo_id, and in the shader load in the texture path, but based on the id it reads its own map.
  14. WIP: Replicating Cubes - Instanced Animations and Bullet

    cool stuff. If you need inspiration for similar stuff, have a look at this:
  15. How to connect points to other points by attributes?

    you could use the Polypath node. Might have to use a join node first after merging.
  16. Boolean random seed per stamp??

    there are never stupid questions. Better to ask and spend 5 minutes to solve the problem than spending 2 hours trying to do it yourself. Sometimes one can't see the forest because of all the trees
  17. Boolean random seed per stamp??

    your technique is correct. your seed in your rand() function is not. $NCY is equal to the total number of copies, hence the same looking glass as it will always stay the same number. What you want to use is $CY which is the number of the current copy.
  18. Houdini engine smoke

    you could do a simple particle simulation and then rasterize them to get the volume. then control density based on age of your points.
  19. all you need to do to create a vector that goes from each point to your target point is the following: vector p0 = point(1,"P",0); vector myvector = p0 - v@P; to calculate the degrees between the two vectors you can use this formula angle = arccosine((vector1*vector2)/(length of vector1*length of vector2)) and this will yield the angle in radians which you then can convert to degrees. you can read more about that here: https://www.wikihow.com/Find-the-Angle-Between-Two-Vectors in vex that looks like this in a point wrangle: //normalize normal vector to make sure the vector length is 1 v@N = normalize(v@N); // get the length of myvector float length = length(myvector); // get the dot product between the two vectors float dotproduct = dot(myvector,v@N); //get the angle between in radians. Note that we do not have to multiply length of my vector with the length of v@N because we know that v@N = 1; f@angle = acos(dotproduct/length); //convert from radians to degrees. f@angle = degrees(f@angle); Lastly you can isolate whichever points you want based on a threshold of f@angle
  20. Flickering colours in slow Coloured Smoke

    hm yeah I see the problem. That is a good question. I am at work right now, but I will try to dive deeper into it when I am off.
  21. Flickering colours in slow Coloured Smoke

    I will have to look at a scene in order to be able to trouble shoot properly. Right now I am just firing from the (dot)hip
  22. Flickering colours in slow Coloured Smoke

    Thats awesome. Yeah it makes retiming mostly pain free for sure. so I am not sure this is the reasons why, but if you go to advanced < bindings on the up res node, at the bottom you can specify extra fields that it needs to take into consideration from the low res volumes. Try to input the name of your color volume there.
  23. Flickering colours in slow Coloured Smoke

    can you share the file when you get home?
  24. Flickering colours in slow Coloured Smoke

    that is correct. however if you dive inside the retime node and look at how it is build, you will see there is no advection going on. its a sequence blend, trying to interpolate v@P over time. This calculation is fairly easy to do on points, but not on voxels.
  25. Flickering colours in slow Coloured Smoke

    you can cache subframes into whatever format you want. coming back to the original question, where is the smoke getting the color from?
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