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Showing results for tags 'vop'.
Found 68 results
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Rotating a point using local axis? Can't figure it out...
ron2812 posted a topic in General Houdini Questions
Hi everyone! I need to do a local rotation using an Attribute VOP for individual points of a grid and just can't get my head around this... If I e.g. rotate along the Z-axis and THEN rotate along the Y-axis it again rotates over the world's Y - not the shifted local Y-axis with a new orientation after i rotated over Z. What I basically need is taking the newly oriented "local" axis into account - the Y-axis should always point upwards from the upside of a cube. No matter how the cube is oriented. I hope you guys know what I mean... i attached an image to clarify. Also I attached a very simple example with 3 Attribute VOPs for rotation over each axis. No matter how the cube is oriented, it always rotates over world-axis. Maybe somebody can point me in the right direction? testrotation.hiplc -
Houdini Rounded Edge VOP: Seeking Example
syntheticperson posted a topic in General Houdini Questions
I have searched the web for an example on how to use the Rounded Edge VOP http://www.sidefx.com/docs/houdini/nodes/vop/roundededge.html [www.sidefx.com] But was unsuccessful. I have a 3D model which is very reflective and has sharp edges. It looks dark in the environment, because the edges are too “perfect”. I want the edges to be rounded just enough to catch light and reflections. Can any one provide a simple example on a cube? thanks -
Lately I have been trying to wrap my head around transforming point positions with the use of matrices in VOPs. To do that, I tried the following: Lets assume I have 3 points with their position vectors A, B and C which come from an alembic and are constantly changing values. I use a time shift and set it to $F + 1, and extract the same points position vectors, which are now called D, E, F. Then I set A,B and C into a 3x3 matrix, transposing it (to get the vectors in columns instead of rows) and do the same with D, E, F. After all this, I multiplied the inverse of the matrix containing ABC with the one containing DEF (this was not inverted). The resulting matrix was multiplied with new Position inputs, but the resulting transformations didn't match the original ones... What am I doing wrong? Thank you.
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I sim a particle system, I want to put some nois after sim but Cd color is not baked at the particles, how can I baked it ? does Anybudy have clue ?
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Longest Axis, Octant, Boxify, Hexplanar Mapping
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Multi-context Bend.
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Hey guys, I'm struggling to understand some things in mat-level custom shading. Reading the manual and watching the masterclass didn't really help. I'm trying to use noise VOPs to drive the color (or displacement ...). But for example plugging a unified noise to basecolor yields no result (as most other noise VOPs, except bump noise). What am I getting wrong? Why do some nodes work, even though I'm plugging a float output in a vector input, and others don't? Thanks in advance. Cheers, Yulyan
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Hello All, I'm newer to Houdini, and working to jump into setting up some simple/fast solutions for wrapping particles around a mesh. Not sticking to the mesh, but flowing over. I'm a professional Nuke compositor with general experience in Maya, so will understand most terminology, but certainly completely new to Houdini, so open to all suggestions and breakdown's of the principles. The end goal is to drive a curl noise vortex up in Y, and place geo within the field that the noise will wrap and flow around. I have attached my test HIP file. I've been trying to combine this tutorial's use of the cross product and XYZ distance, with the VDB setup from Entagma's Curl Noise tutorial. Other than there being a good possibility I'm on the completely wrong path for this type of effect, it seems I may be confused on properly using the cross product in the VolumeVOP. The attached file doesn't touch properly adding or multiplying in the curl noise, because I want to correct my issue with the field to begin. Thank you all for your time, patience and help. My Best, Josh curl_noise_trailsTest_003.hipnc
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Hello, I was following a tutorial on how to create a sun in houdini, and I came across a technique used to keep advected points bound to the original surface where they were scattered from (in this case, a sphere). For the purpose of advecting the points, it was created a popnetwork with a curl noise affecting the velocity. To keep the points moving on the surface, the instructor did 2 things: -Turn the sphere into a mesh and convert it into a VDB. -Create a POP VOP, with a Volumesample and a Volumegradient, reading from the vdb converted sphere. After this, the gradient was inverted and multiplied by the output of the Volumesample node and added to the original positions, inputing into the new positions. This last point got me lost. The instructor referenced in some abstract drawings the utility of both this nodes, the Volumesample and Volumegradient and I tried to cross check with Sidefx's Houdini documentation but it didn't have that much info on the subject. Can some one briefly explain what is happening inside both this nodes, and their respective outputs? Thanks.
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Remainder is always 0 when any num. is divided by 2. MODULO problem.
suraj kushwaha posted a topic in General Houdini Questions
Hello People, I have been trying to produce a Boolean value i.e. 0 or 1,So that i can use it as condition for my (IF Block) in pointvop. But whenever i am dividing Ptnum by 2 using the node modulo is always leave a value of 0. Help!! -
Possibly a stupid question. In older versions of Houdini there was access to the 'accel' attribute in vops. Where's it gone? I'm using H15.0.416
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control width attribute with a ramp vop [solved]
ejr32123 posted a topic in General Houdini Questions
Hey! I was looking at the scene found here: https://www.sidefx.com/forum/topic/26032/ I want to control the width of my wire with a ramp vop. This scene was created with an older version of houdini. When I try to recreate it with the updated nodes, it does not work. The original (which you can see in my scene) uses a vopsop and the add attribute, both of which are obsolete according to the manual . I tried recreating with the new nodes, but it does not work. Could some one let me know what's going on? Thanks! edit: for some reason the attached scene crashed for me when I downloaded and opened it. However, if you open houdini first then open the project (as opposed to opening file directly) it seems to work. line.hipnc -
Hey guys, it is possible to mirror noise within vops? Im trying to create some sort of fractal noise, for example on a grid of 4, having the same noise on each grid but flipped / mirrored. Thanks!
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Hello all, I'm modeling some tentacle creature and ran into a problem. I don't know how to stamp attribute into the VOP sop and use it to drive turbulent noise to randomise shapes for every copied tentacle. Then i want to copy that tactically geometry again and randomise tentacle shape and/or animation. I have tried to just bind stamp("../../copy" , "id", 0) into the vop and connect it to Offset of the Noise, but for some reason, Houdini just stuck in the loop. Please see .hip below. I feel like it is something obvious, but I cant see it. Please advice StampinVop.hip
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Hello ! I made an explosion and I try to make it loop with Timeshift and volume mix nodes, Sadly I feels its too limited as the fading between the two volumes are quite obvious. Is there a way to mix volumes with a VolumeVOP ? The idea is to add simple 3d noise as the volume fade in and out. Thanks a lots
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Fixing a value once it reaches a certain number
killerseven posted a topic in General Houdini Questions
Hi guys, I was hoping someone might have a clue here...I have a vop with an object running over an rbd simulation to activate pieces, the only problem is they seem to be becoming inactive again after being activated. So the basic question here is if there is a way to fix an attribute once it reaches a number (in this case 1) so it cant change back to 0? Cheers! -
Hi,I am working on crawling insects solver and actually i need your favour,there are some issues,actually particles leaving the surface after some level of accel...i dont understand why its happening... plz can u tell what i am doing wrong...and also any other suggestion is also welcomed...Thank you for your precious time PFA Nashrat Shahi test_v01.hip
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Connecting an image from /img as a texture in /mat via a null node
marque_pierre posted a topic in Lighting & Rendering
From SideFX' tutorials on UV Basics III, I understand that you can connect to an image brought in and edited in the /img context (via the null node, named OUT for example), and then reference it in other contexts, specifically the /mat context, via the syntax of op:/img/img1/OUT On the SideFX forums I got the suggestion of instead using op:/img/tex/OUT This is what I get. Actually, I get that whether I use “op:/img/tex/OUT” or the standard “op:/img/img1/OUT” Oddly, my material turns this light pink as opposed to the standard grey, either way, when I try to call in the texture from null node. I want to be able to edit my texture images with all kinds of colour corrections and procedural tools over in /img and then bring them in live into my shaders in /mat. What am I missing, or messing up? -
This is driving me crazy. Trying to get a simple colormap VOP example working. No errors but my image is not showing up mapped to my grid. Could any vexperts possibly have a look at my .hip? As good as the revised H16 documentation is, it could greatly benefit from actual downloadable .hip files! colorMap_VOP.hiplc
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Hey guys, I'm new into vop's and wonder why I dont get any result, when distort the nomals through an turbulent noise node? Is there any tutorial which covers the vop basics? Like what the colors mean and what datas need to flow through nodes to get results? Thank you for your help
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Hey guys, sorry for my english There is a way in Houdini to detect the collision and have a organic style deformation without dynamics to avoid the intersection of the meshes? I have some geometry groups (tentacles based on curves) in a single object, so, I thinks is possible with volumes and a vex expression with if and else, but I'm not so good with vex, i'm still learning. So, using a foreach loop , maybe converting the mesh into volumes and use a scatter to have the surface and inside points to detect their position, how can I import in a wrangle the groups and their points info to create this type of action? I know the message but i don't know how to write it, some ideas? Thank you
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wondering how to make a sphere move in spiral way in X,Z axis only , either starting form the middle and expanding outside or vice versa, so i can emit from it flip simulation
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Hi, I am looking for measuring volume by VEX and/or attributeVOP, instead of measureSOP node. Basically I have mega voronoi fracture model. After that, I want to apply for volume calculation with loop node and compile node. Key is that I cannot use hscript expression in measure>center with compile node. That's why I am looking for another method.
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Using Align to calculate angle*axis between two vectors
KiLa posted a topic in General Houdini Questions
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 couldn´t animate it by keyframing the Bias of a mix node. couldn´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 isn´t the same and while changing the bias of the mix node all the points change it´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 couldn´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
