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filip

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  1. filip

    Matrix rotation

    Messed around with something else in the meantime. I almost got this, but not quite because I can't figure out how to get all the points to move where they should be without overshooting and messing up the pattern. Still playing with it, though, maybe I can figure it out. https://youtube.com/shorts/C9K2vh8eky0?si=Ol01XK16cMV4ajOR
  2. filip

    Matrix rotation

    Hmm, I can't figure out how to attach files anymore. I know on my first posts I uploaded some, and I can select those with "Insert existing attachment", but I don't know how to add others. Maybe the number of files I can upload is limited by my account level? So I uploaded it here instead: https://we.tl/t-Zst35GHTIQ It's going to miss the HDRI and a bokeh image. Also, for me sometimes when I open it seems to have a display bug, not showing the cloned objects. Just disable and enable the spline for example in the object manager and it refreshes. I tried to comment the nodes, but they're probably not going to make much sense unless you watch the Entagma video. I also rendered a short animation with it: Unrelated to this one, but if you want, you check another one I did based on some other Houdini tutorial: https://youtu.be/OvZsweifA_U?si=tt2pkN7IH84Mifr1 I can upload that file too if you think it's of interest.
  3. filip

    Matrix rotation

    Thank you for the Loop Carried Value suggestion! That was the main issue. I misinterpreted that for loop. Since it uses values that were modified in the previous iteration Loop Carried Value was necessary. Another thing I had to do is do an Inverse Matrix on that matrix. Either that or reverse the order of the cross product to generate the bitagent. I'm not sure if this is because I messed up something else somewhere or C4D and Houdini store matrices differently. But in the end it works just like in the tutorial. The spline distribution doesn't work quite the same. It has issues at changes of orientation along the curve while this doesn't.
  4. filip

    Matrix rotation

    Hi, I'm trying to reproduce this in scene nodes However, I'm having some trouble with this bit: Particularly the matrix rotation. I have the bitangent, I have the theta. But I can't figure out how to get a matrix and rotate it using the bitangent and theta. I'm guessing for the last line I can use Transform vector with that matrix, but I'm not absolutely sure about it. But the main problem is the matrix. How do I do that in scene nodes? I tried matrix from axis giving bitangent as the axis and theta as the rotation, but it gives completely different results than what I get in Houdini. Bitangent and theta I got to the same values as in Houdini, so the problem must be building and rotating that matrix. Edit: Well, I guess my solution for the last line, to use Transform Vector, could also be wrong and that's why I'm getting the wrong values? But as far as I understand, multiplying a matrix by a vector means you're rotating that vector? So that's why I assumed it's correct... Edit again: It SEEMS that actually I may have actually got the matrix correct. I get the same matrices in Houdini... or at least, I think. For example, this what I get from one of the matrices in Houdini: [ 0.933975, -0.32385, -0.151037, 0.0, 0.3571, 0.830432, 0.427623, 0.0, -0.0130599, -0.453325, 0.89125, 0.0, 0.0, 0.0, 0.0, 1.0 ] And this the matrix for the same point in C4D: Is it the same thing? I mean the values are there, but are they in the right positions? If they're correct, then I can only assume that my interpretation of the last line is incorrect. How do I do that rotmat * normals[k]?
  5. Yeah, I'll probably upload it, but I'm still working on it. At the moment it's still a mess. Changing the text (like I did in the video above from Hello to Core4D) is also quite painful. I can say though that using the Heat Map I can see the if I clone by using Transform Geometry, that looks to be the bottleneck. Those get red and take over 90% of the calculations. Using Matrix Op to do the cloning (and using Multi-Instances) works super fast. I'm not sure if I can use Matrix Op in a Nodes Mesh? I can't figure out if I can get out Geometry out of an Op? Either way, I wouldn't have the multi-instance option in that case.
  6. Thank you! I'm working on a Led Matrix Display thing. https://imgur.com/aHf91lk I realize the Object Group is experimental, but with the cloning I have in this thing, the performance is not too great if I use a Nodes Mesh.
  7. Thank you very much! One more thing, is there a way to switch between two Ops? These are in an Object Group capsule. I want to have an input (like a boolean or a drop-down menu, doesn't matter) that switches the output between these two. Switch and If nodes don't seem to support Ops? I can probably do the switch further back in the network, but it would much simpler if I could do it at the end.
  8. I have an array that I'm slicing based on a range. You can see in the data inspector the result of the slice array node. That's all good, but how can I then separate all those 7 arrays so I can do stuff to them separately. The range is 0 to 7, the multiply is by 24 and the add is 24 also. So basically, I have an array, and I want to separate it by 24 values, first 24, second 24 and so on. I tried various things, like Get Element and so on, but nothing worked. Is there another way of doing it if slicing like this doesn't work? Except using a Slice Array for each slice. I guess essentially I want to get an array of arrays which I can then select with Get Element or something similar. Thanks!
  9. filip

    Help with looping

    Thank you both! Definitely improved my understanding of the LCV node. Oh, and wanted to mention that it gets to 10 iterations with no problem. Didn't try more. It's actually faster than the Python Generator version I did. But I'm sure that script could be improved too, I'm no programmer.
  10. filip

    Help with looping

    Hi! Thank you for the welcome. I attached a scene. In the meantime I sort of managed to make it work, but I think poorly. I got rid of the inner Loop Carried Value and now just have one that feeds back the array. It does what it's supposed to, I guess, but at 10 iterations it seems to lock C4D or at least I didn't have the patience to wait for the calculation to finish. And I think the problem with it is with the Erase Elements node. Without that I can get to 10 iterations, but then the old points are kept, so that's not good. Is there a way to fix this loop and getting rid of Erase Elements but having the same result I had with it? I also tried a version (disabled in the scene) that feeds back the spline and then goes over its points again. I tried this based on the Geo Feedback Loop scene from the content browser, but I couldn't make it work. I mean, it only works for 1 iteration, if you can call that working. Maybe it's not the correct way to do it with splines? Any other way? This is really just as an exercise because I still don't understand how the Loop Carried Value node works exactly. I did this in Python with a Python Generator and it was much easier and had no problems with 10 iterations. So if you see other things that can be improved about this, please let me know. Thank you. kock_send.c4d
  11. filip

    Help with looping

    Hi, Can somebody help me with this? It's a simplified version of what I want to do, but basically in this version, I want to loop over the points of a spline and insert a point in the middle between each two of them. That loop (the inner one) seems to work. But then I put that in an outer loop, with the idea being that I want to go over the resulting spline from the inner loop and apply the same procedure again. However, it doesn't work. I just get the same points over and over again. I don't know if the problem is with the inner, the outer or both loops. Thank you. data.zip
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