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Search the Community: Showing results for tags 'vop'.
Found 45 results

Hi, i am trying to calculate angle and axis between two vectors, using the Align VOP.. I has an option to export 'Angle Axis'  its help card says: "This operator computes a matrix representing the rotation around the axes normal to two vectors (their cross product), by the angle which is between the two vectors. The resulting matrix maps the first vector onto the second. If both vectors have the same direction, the result will be an identity matrix. If the vectors are opposed, the rotation is undefined. This can also output a quaternion representation of the transformation rather than matrix." What does it mean? In the attached scene, i have an open circle which have some normals. Next i am trying to calculate the angle/axis between the normal an up vector, but the angles i get from the Align doesn't make any sense. Cheer k angle.hipnc

Hi there, I am trying to build a propagation driven blend / morph effect to change the look of a geometry. But I am already stuck by transfering the atrributes between the geo A and geo B. I managed to build a set up where I change the geometry by using a attribute vop and subtracting B minus A. Here come the BUTs couldnÂ´t animate it by keyframing the Bias of a mix node. couldnÂ´t use a propagation effect with scattert points In the second set up I tried to change the set up by using a scatter node insted of the normal geometry. It works but it seems that the point order isnÂ´t the same and while changing the bias of the mix node all the points change itÂ´s position?! In the scatter node I unchecked "Rondomize Point Order" but without any effect. I also tried to use set up with the change from lowres mesh to a highres mesh, but here I couldnÂ´t get solution with the scattered point, because of the primitive Attribute node in the second Vop. I also tried to recreate it with point cloud node but failed as always. I am pretty new to Houdini and I know that I am missing a lot of foundation knowledge, it would be great if someone could give me a hint what I am doing wrong. Thanks and all the best Dennis 170422_position_transfer_001.hiplc

 vop
 attributes

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First post, and pretty new to Houdini (coming from C4d). What I'd like to do is have a flat grid of polygons that are acting as "pixels" whose color is driven by an underlying image sequence. That much I have been able to figure out using a grid of points, and then mapping a simple 1x1 square per point. I've been able to get a color per copy based on an image sequence as well, using a vopsop. What I'd like to do, is for each copy, read the luminance or color value, and be able to map an image to certain ranges of luminance. (example: black  nothing, gray  small circle, white  big circle) What i've tried so far always maps the pixel image to the whole grid, and not to the individual square. Any direction would be wonderful!! I could be heading in the complete wrong direction with this. I'll attach my hip, but without the image sequence it'll be hard to see what's going on so far. I'll upload a video as well showing the basics of what's happening so far. Pixel Grid.hipnc example.mp4

Hi everyone, trying to figure out how to randomise the number of iterations of a pc open in a vop node, based on a per point random the goal is to make variation in the speed of the propagation. I join a simple file, if somebody can help me it would be really apreciated Thx by advance Cheers basicpropa.hip

Hello, I'm attempting to recreate something similar to the reference geo in this link: I'm using a tube and then painting where I want my displacement but I'm not happy with the results as it isn't really resembling the reference image. Does anyone have any suggestions as to a different way to approach this? Thanks for taking a look. disp_geo_js_v01.hip

 displacement
 abstract

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I am trying to mimic a rail spline like you would use in Cinema4D. Essentially I would like each point normal to look at the point with the same index on another curve. From what I've found on getting a direction from two vectors is to simply subtract B from A. However, this does not seem to be the case. (See attached file) Is there more to it than simply subtraction? Align_Normal.hip

Hi I am a new user of Houdini living in Korea. I want to give a vector blur in the direction of the dots. I tried to draw a pass and draw a vector blur in nuke, but the direction is straight. I tried it with normal and I tried it. Failed to resolve for a week. So I simply gave the vector blur to the sphere and it did not work. It seems to be a render problem and I do not know what the problem is. I upload two hip files. Why does the value of the copy node remain the same? Finally, how do you study vop? ... I know that it's related to arithmetic math. But it 's confusing and hard to see. Please help me.. vector_2.hip vector_1.hip

Hi there, I have been trying to figure this out but probably don't know enough about transform/rotate matrices and how they work. What I got is a circle of flat boxes all orientated in Z. The flat side is always faced to the center of the circle. See attached image for better understanding. Now what I want is a rotation around the local X axis of each box. Attached is an example file to see what should happen and also what I have come up so far. To better illustrate what the end result should be there is the same setup built with a copy SOP and a transform node before to do the rotation. Now the solution I came up with kind of works. The main problem is that there seems to be some sort of scaling. You can see this when viewing the solution made in Houdini in template mode. Maybe someone can point me in the right direction. Also, my setup is not very elegant so if there are other or better solutions I would love to hear them. Thanks in advance! Dennis rotate_objects_local_v01.hiplc

Hello, I am trying to do some edge detection using a kernel. I need to do this using standard SOPs/VOPs. http://setosa.io/ev/imagekernels/ I saw a tutorial from Entagma (https://vimeo.com/169437381) that basically does the operation by hand splitting out the vectors and multiplying them but it's quite tedious and you dont really know what vectors you're multiplying (QUESTION: is there an order in which pcfind returns the array of points eg. clockwise closest to furthest ?) Is there a better way (using actual matrices / knowing exactly which points) ? thanks!

I am trying to scatter some points on a circle. But I want the points to be scattered more near the center and less towards the outer side. In the old Houdini Scatter I could do it by making my Circle Primitive type to "Polygon" and then uncheck "Divide Non Convex Polygon" on the scatter node. However, in the new scatter node of Houdini 14 and 15, this option is not available. Here is what I am trying to achieve, this is with the old scatter node. This is what I am getting with the new scatter node. Please help.

hello,How do I connect using vop? thanks,please help me.

Hi Pretty much the title In VOP I can use the "Import Primitive Attribute" node to do it, but I'm not sure what's the recommended way to do the same in a wrangle. I noticed that the IPA node is actually just a snippet, which obviously answers my question, but I was wondering if there was a more straightforward (a.k.a shorter) way to do the same Thanks EDIT Someone answered my question and apparently just using @primnum works in wrangles. However, now I'm more confused. I created a sphere and put a f@test = @primnum; in a point wrangle, the results are some numbers, but what do these numbers refere to?

Hi, As soon as I apply a material shader builder to any object, the object turns white in viewport. I can see the shadows but even the basic diffuse color, that is greyish, does not show up. Any textures that I apply also does not show up in viewport. The textures are not procedural, they are basic images, the renders come out fine. On the contrary, If I use a default mantra surface shader, Everything shows up correctly on the viewport. I prefer building my own shaders from scratch so could anyone please tell me how to preview basic changes made to the material shader builder on the viewport. Thanks

 vop
 material shader builder

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Hi all, I'm looking for learning resources to help me with writing a new operator type, but I'm also very interested in writing shaders in general. For writing shaders I've essentially only found an old odforce article from the wayback machine. It could be out of date as far as I'm aware, but I cannot find anything else. Anyway, rather than writing a whole shader I'd rather create a new operator, but I can find no resources on this at all. Is this in the documentation somewhere and I've missed it? For example, the $variable notation I've not seen anywhere else except when I cracked open an existing operator, along with essential looking syntax like the $isconnected_variable to determine if a variable is plugged in. If someone could point me towards some sort of documentation I would be very grateful.

Hello I'm reading about the new H15 for loops. I'm trying to recreate this kind of pattern using the for loop So I built this network But, as you can see, there's no output and I'm not sure why (don't mind the bypassed fit range there) There's nothing in the scene besides a camera and a default grid and generic HDR Thanks.

Hey, I'm trying to create blow effects for my particles which will be snow. At this moment I have smoke advect which drive my particles but it still looks really bad. I would like to create light snow/grains like a dust which will unhide object after blow. Fox example: ball is hidden under the small amount of snow and someone blow this snow using mouth to unhide this object which is under it. hope it is enough clear to understand what I mean. advec.hipnc
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 vop
 houdini grains

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Hey everyone, I am in the process of creating a digital asset and its basic building block is a circle. First I have the user plot three points in 3D space. And from these 3 points which form a triangle, I am creating a circle that circumscribes this triangle. The algorithm I have so far from gathered resources are below; 1.) calculate the normal vector to the triangle formed by the three userdefined points. 2.) use a reference plane into which this triangle will rotate onto, say the XY plane 3.) rotate the three points into this reference plane after calculating and building a rotation matrix 4.) find the center of the circumscribing circle from the three points 5.) calculate the radius of the circle which is easy 6.) build the circle on the reference plane 7.) build a reverse rotation matrix to rotate the points back to the original plane I'm not sure what I am doing wrong but the code I have so far works only if the points lie on a plane in 2D space. The minute the points have values in the 3'rd dimension, it gets wonky. I'm also not sure if the rotation matrix in Houdini does the rotation about the origin or about the pivot of the three points. I can share the code to take a look at it. If anyone has any solutions or suggestions, kindly let me know! Much appreciated!

Hello, I think I figured it out whilst making the image! But I figure I'd ask anyway. Does the input order of a multiply node determin its output? In other words, if a float is the first input a float is the output.

Hello Does anyone else on linux distros (we use Centos 6.5) freeze when promoting parms when in VOP contexts ? It did it on H14 and it still does it on H15. No ram/cpu spike, just frozen. Sometimes when you can activate a UI element it will come back, but rarely.

Hi everyone, I'm trying to make something similar to this using VEX. For some reason my cube its "jumping" every time it changes direction. (see attached video) Here's the code I wrote so far: f@random = random(@Time); @random = fit01(@random, 0, 3); //moves in X if (@random < 0.5){ @P[0] += (@Frame / 15); } //moves in Y else if (@random > 0.5 & @random < 1.5){ @P[1] += (@Frame / 15); } //moves in Z else{ @P[2] += (@Frame / 15); } I tried doing the same using VOP (see attachment) but I'm getting the same results. randomXYZ.mov

I'm using Houdini 15, and i'm following CmiVfx Connections tutorial, chapter 4 where you create sphere and grid and a vop sop wich is suposse to tell which point from the sphere is closest to which point on the grid. I know things changed with the latest H release, and i thought i kind of a figured it out, but all i get is constant number and it's not point number that is closest to anything. I'va attached the file, if anyone can look inside and tell me what i'm missing? nearestPTNUM.hip

Hello! in VOP the ptnum is called with a parameter node for the first input (geometryvopglobal) i used an importpoint attribute with sign: integer, input: second input, attribute: ptnum but it returns me zero. if i want the ptnum for the other inputs do i have to create the point number attribute ahead? is the ptnum like an implicit attribute? thanks for helping!!
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 vop
 other inputs

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Hi, I've been trying to figure out a way to get patterns that look like these for a shader. Anyone have any tips or have achieved this before? Or if you have a way to do it in geometry, that will work too. Thanks

Hi there! I just learned to build multifractals using a forloop vop in H14. (see images attached) This was quite easy by putting a noise node inside the forlvop and adjusting the iterations. Just wondering how to replicate this using the new forloop in H15? Best

Hi guys I'm doing a BSDF mix in vops with a float attribute which is defined by an attribute transfer. but as you see in the image the mix between two shaders (sss and steel) is not correct despite the attribute is 0 or 1 for all points. can any one please explain to me the probable reason? is there an alternative way? Thanks in advance