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Everything posted by Jesper Rahlff

if you look at the last file I fixed the problem in dops. Just divide your one curve force into 2 curve forces and it works as in sops

I don't have the answer to why the particles move at different speed up the curve, However if you are looking to have the particles move at exactly the same speed here you go. followPath_alternate.hipnc EDIT: actually it is because you are grabbing both curves into one force. if you create a curve force for each curve and assign them to the paired particle stream it works in fine followPath_dop_fixed.hipnc

hm it should work. Did you set the control influence to 1 and then remap the values?
 5 replies

 pressure field
 turbulence

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What's the best way to displace a pyro volume in SOPs with or without rest fields?
Jesper Rahlff replied to magneto's topic in General Houdini Questions
for the dual rest field I believe the math needs to be as follows: (rest * rest_ratio) + (rest2 * rest_ratio2). the output of this will now be your rest field 
another way is to animate your Volume source node, you can animate the scale from 1 to 0 in your density field

people would be more keen to share an example file with you if you uploaded one as well showing that you have tried to recreate this FX on your own.

Earth atmosphere with Redshift (or finding the "ANY" KEY)
Jesper Rahlff replied to Pancho's topic in Effects
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 
Earth atmosphere with Redshift (or finding the "ANY" KEY)
Jesper Rahlff replied to Pancho's topic in Effects
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. 
Earth atmosphere with Redshift (or finding the "ANY" KEY)
Jesper Rahlff replied to Pancho's topic in Effects
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? 
is there a hotkey for removing a node from the network?
Jesper Rahlff replied to Valent's topic in General Houdini Questions
I just use CTRL + X to cut the node. keep doing that and you overwrite your cut history essentially removing the node 4 replies

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 interface
 disconnect

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group by bounding regions with operator path reference
Jesper Rahlff replied to bonassus's topic in General Houdini Questions
Try using chs() specifying that the input value is a string. 
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

overwrite default state based on parameter on HDA
Jesper Rahlff replied to Jesper Rahlff's topic in General Houdini Questions
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 
overwrite default state based on parameter on HDA
Jesper Rahlff posted a topic in General Houdini Questions
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 
overwrite default state based on parameter on HDA
Jesper Rahlff replied to Jesper Rahlff's topic in General Houdini Questions
No one? 
you are welcome. let me know if anything is unclear

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

Same UVssame object multiple timesdifferent textures (UPDATE)
Jesper Rahlff replied to Justin K's topic in General Houdini Questions
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. 
WIP: Replicating Cubes  Instanced Animations and Bullet
Jesper Rahlff replied to MildlyRedBeard's topic in Work in Progress
cool stuff. If you need inspiration for similar stuff, have a look at this: 
How to connect points to other points by attributes?
Jesper Rahlff replied to GreenAvoy's topic in Modeling
you could use the Polypath node. Might have to use a join node first after merging. 
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

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.

you could do a simple particle simulation and then rasterize them to get the volume. then control density based on age of your points.

how to find faces/points which are facing to another point
Jesper Rahlff replied to Valent's topic in General Houdini Questions
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/FindtheAngleBetweenTwoVectors 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