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JJ FX

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    JJ FX
  1. So instead of point() use points(), eg.: points("../node", 0, "this") LOL
  2. Hi, So I have a string point attrib on a sop node, let's say it's s@this = "Yellow". When I bring in the attribute into node parameters with houdini expression point("../node", 0, "this", 0) it always evaluates as 0 unless the string is empty s@this = "", then it evaluates as -1. So I guess point() doesn't see string attribs. But what I need is a string and the exact value of that string! I don't care if it's houdini expressions or python, as long I can just get this attribute and use it inside node parameters!
  3. Hi, So let's say you have an animated cube in world space with no deformations, just rotation and translation. The animation is baked onto the object, so I don't have the access to the animation rig (eg. alembic). What I need is a pivot position for that animated cube. Also we don't know if the pivot is in the center of the object, it can be anywhere. At first I thought all I need is just to do maketransform() and then extract the pivot from the matrix. However when building matrix with maketransform() you need to provide a pivot, so when extracting you will end up with that. So... how can I extract the pivot point from animated object? Is it even possible?
  4. Hi, What I need are dynamic constraints. Going from "inactive" to "active". Something similar what you have in bullet solver. I've found this example here, but for me it's probably outdated and overcomplicated for simple stuff like that. I've watched some Master Class on Vellum and it looks like it can be done just with Vellum Constraints DOP. So I did a very simple example with pop group and it's working just fine when you're going from active > inactive. But when I want to go from inactive > active the constrains are not updated. How can I update my constraints to go from inactive to active? how-to-activate.hiplc
  5. Hi, So when i render inside houdini (render view > render) everything looks just fine. But when I render final files to save them I keep getting this weird shadow shape. The light that casts this weird shadow is a geometry light with depth map shadows. When switching back to raycast shadows it's all fine. How can I fix that to have depth maps shadows? So Sidefx says they only recommend ray-traced shadows for area lights, as they might produce artifacts. And the reason why IPR/Render View renders just fine is because IPR/Render View doesn't support depth map shadows (huh, did you guys know that?!), so it defaults to ray-traced during the render anyways.
  6. Hi, I can't find where I can change snapping settings in the scene view. I'm not talking about snap (X) but the snap with Ctrl. Eg. By default Ctrl + T snaps every 0.1 unit. I'd like to change it. SOLUTION: Ok I had to ask sidefx support. It's right click on the handle -> Handle Parameters
  7. Curve edge normals?

    Oh yeah, thanks!
  8. Hi, So when you have a curve and use Polyextrude SOP by default it uses prim/edge normals. So I've been thinking, maybe edge normals are precomputed already (you know, like normals in openGL even tho you don't have them as an attibute but you need them to draw properly in the viewport and render)? Or maybe it's just Polyextrude SOP that is computing that. Do you think I can somehow access the edge normals? I can recreate them myself, but maybe that would be futail, reinventing the wheel.
  9. Instantiate objects in Shader

    Yeah I tested that yesterday and also tried old Instantiate object. And both perform exactly the same. I guess packed prims are the fastest way these days
  10. Instantiate objects in Shader

    Thanks! I will look into this! Well... I need to instatiate geometry onto milions of points. Copying creates more expensive and slow cache. Example: grass
  11. Hi, So I want to instantiate objects in shader. There is a Point Instance Procedural VOP node. However I have no to little experience in shader builders in houdini. This node has geometry output, I'm not sure where this even should be plugged in to make it to work and just see anything. Any help would be super helpful!
  12. What did it do? Can you give an example? Removing edges from exterior does not make sense. Anyways groups ("outside" for exterior) are still there and you can use those to get what you want
  13. Hi guys, So recently I've been doing some really heavy math within wrangles. And I was disappointed when I checked the performances between a point a prim wrangle. They both have same calculation times. Usually my code goes like: int points[] = primpoints(0, @primnum) for (int i=1; i<len(points); i++) { // Do more stuff here // And even more for loops here } So if this is run in prim wrangle the calculations run per prim (because its a wrangle), and then per point (because of the loop). Switching to point wrangle it should be like (pseudocode): foreach point (because its a point wrangle) { int points[] = primpoints(0, @primnum) for (int i=1; i<len(points); i++) { // Do more stuff here // And even more for loops here } } So it would just create an additional loop, possibly causing some overriding of the values. However both methods performs exactly the same. I've tested it on 30mln points geometry many times. Can any1 explain me why?
  14. OMG THANK YOU, thank you, thank you!!! I didnt know this would be so straightforward
  15. Hi, So I baked out some kind of vector flow map on the character. The idea was to use it back in sops over deformed character. Ofcourse the bake is done in a single frame. So when those vectors are applied to a deformed mesh, they are constant to the world space, which completely make sense, but is useless for me. Since this is a vector map and its stored as a color map, there is some kind of "gradient" on the deformed mesh that could be computed as a change of the flow map? Do I make sense? For example you have a character where the flow always go from the shoulder to the hand. And once the character gets deformed (animated) I want the flow (vector) to always follow the rule "from the shoulder to the hand". And yeah my flow is a vector, not a float. And I need those vectors in sops. Dont know if I explained this good enough. Any1 any tips?
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