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mattjakob last won the day on August 11 2019

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About mattjakob

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    Matt Jakob
  1. Lately I've been thinking about isolines and Im struggling a bit to wrap my head around them in houdini... I did some experiments using particles and noise but I feel that's not quite the right technique. A good example of the effect Im trying to recreate is this: or the incredible OFFF titles: Any ideas how to approach this ? Thanks! Jx
  2. I added a custom operator interface to a Point Wrangle node to get a point position (from an add node). In the screenshot below I'm referring to the 'Target' string input in the UI / parameter name 'opPath'); Using the standard chs() function I can get the value of the node dropped into Target/opPath. Using the op: operator I was assuming this data would be live (eg. if I move the point geometry referenced in Target/opPath I was expecting the coordinates returned to the point() function to change accordingly) ... but it doesnt happen (stays whatever value is set at frame 0). The solution (screenshot) is to hard code the path to the target object using the op:operator (position coordinates get update if the geometry changes). If I uncomment the first line (and comment the second) then the coordinates no longer get updated. It's annoying as I'd rather not hardcode the path to the object in VEX and rather use the chs() UI interface. Any idea? (also some clarity on how the op: operator works and when is it needed versus just referencing paths without it would be appreciate as couldnt find much on the subject) THANKS!
  3. Probably a very noob question... but what are the differences and benefits of the two ? They both run a simulation over a SOP network... are they any different in what they can achieve ? Thanks! J
  4. Im trying to connect an apply data to a sop solver (even the documentation page of the sop solver says that one of the most common inputs is the apply data node) but no matter what I always get a "Connection to input 0 is the wrong type". The only solution I found is to go through a multisolver node... which is fine but I wish I could understand what's wrong with connecting an apply data node directly to a sopsolver ?? What I would like to do but returns error (despite documentation): The solution I found: Thanks! J
  5. Spray paint non intersection

    oh that's cool... Ill play with it! Is there an easy way to control the size/density of the spheres ? Is that what you did (setting the density) with spraypaint (dont have houdini right now to test it) ? Thanks!!
  6. The title says it all... I would like to scatter some spheres (with different sizes) like I can do with the Spray Paint tool but making sure they do not interest... is there an easy way to do this ? In the image you can see what I did with the spray paint tool (+ a boolean cut)... the distribution and size is exactly how I wanted it, just I wish they didnt intersect! Thanks!
  7. Invisible RBD collider

    Hello, I would like to have some objects bouncing around inside a sphere. Is it possible to have the sphere geometry transparent but still act as RBD collider ? thanks!
  8. Hey guys, Im playing with the Wire solver and I managed to get a series of wires from one plane to another to dangle (mostly using the shelf tools). What I would like to do is to start with just a couple of wires and over time increase the number. As you can see in my scene file the number of wires is determined by the scatter nodes... but if I animate the points count there the simulation breaks. Any idea ? thanks! mj_wires.hip
  9. Anyone keen in sharing their setup for vector / 2D rendering ? I'm looking for some options similar to Rhino on how to render more technical drawings (wireframes. solid shading, ...) Thanks!
  10. yup that works... but REAAALLY ??!!? I'd love to know why attribs (nor it's local var equivalent) don't work in the transform node... it's really frustrating
  11. uhm... Im trying to avoid using copy stamp as suggested in H16 and use a For Each loop instead... but I cant seem to make sense out of it! (I watched a few videos and checked the help - but they seem pretty useless / over-complicated). I simply want to copy some geometry (eg. circles) onto some points (eg. on a line) + each point has an attribute --> I scale each geometry based on the point attribute. Seems like a perfect iterative loop over points task! When I put my copy to point(s) node inside the for each loop everything works fine (the copy node only receives one point which is fed iteratively from the the for loop). HOWEVER when I apply the transform node and I use vex (@attribute_name) to try to access the attribute value associated to that point to scale my geometry it doesnt work (I get 0). If I try to access the same attribute using a wrangle node it works. Maybe Im doing something silly wrong with the transform node... but what I do seems intuitively right (type the vex attrib name in the scale Thanks!
  12. That's a great tutorial... I also saw the other one by Rohan (see below). THAT'S A REALLY ABSURD WAY TO PASS COLOUR... can't believe it Octane didnt think of something more flexible and logical..... )
  13. I almost never rendered with Houdini but thought of giving it a try... Essentially I created an Octane material and applied it to my geometry but I want the diffuse colour of the shader to be the colour of my points geometry (and not the colour selected in the shader node). Im assuming it's a pretty basic thing but couldnt find a way to do it (played with material override etc.) ... maybe Mantra gets it automatically (seems a sensible thing) but not Octane. In layman's terms I coloured a series of geometries using some gradients and random values (my points have @Cd attributes). Then I created a standard Glossy Octane material. I want my objects to have the properties of the Octane shader (reflection, roughness, opacity, ...) but use the @Cd attributes in the geometry to drive the diffuse colour. Thanks!
  14. thanks guys! in the end I attached the original straight line as a second input to the sweep and selected 'aim at reference points'. @LaidlawFX if I set the up vector to be 0,1,0 then the skeleton instances dont rotate properly along the spline (I think it's called banking ?)
  15. Hello, I was wondering if it's possible to create velocity vectors from an animated sequence (texture). Ideally something similar to Optical Flow. I can extract movement from geometry (eg. use trail to generate v vector of animated VOP) and I can do basic image analysis (eg. convolution kernel operations on coloured points using VOP) so I feel it could be kind of possible to do it but can't get my head around it. In terms of results I'd like to create a particle system that reacts to an animated texture (eg. overlay particles on a animated texture and have them follow the movements in the video) thanks!