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  2. simulating celestial bodies

    sure - would be great if you're willing to share! in case you remember any resources you used that'd be helpful too. fyi - just found this
  3. Thanks, I'll give it a go and report back Was reluctant to do an iterative approach but might be the only way!
  4. simulating celestial bodies

    @nuki something like this --Celestial mechanics--I have Old File very Old
  5. simulating celestial bodies

    Doing some shots of planet earth where I'd like to have plausible transformations for the sun, moon, earth (ideally including its axis wobble) and star-backdrop (rotation only) relative to each other. Since there's different models in respect to their origin and accuracy the matter is a bit confusing for me to untangle. Hence I was hoping someone here might have attempted something similar and could point me to a comprehensive resource. In the end I'd like to have a float slider to adjust datetime driving an approximation of the mentioned celestial bodies' transformations.
  6. Please post a file or at least a snapshot of your shading network. There can be dozens of causes for your problem.
  7. Houdini 19 Wishlist

    I created this as a camera lock indicator:
  8. Hi, you can try to iterate. Start with a first try and find the u-value, where the length between the u-values matches the length of the vector. Here is some VEX Code. Peri is the length of the curve (you can use measure here). L is the length of the vector. u the position of P1. This will surely not work in every situation. But if you start with L / Peri, you have a first guess and probably length between the curve points is greater. So the next du should be a bit bigger. If the length are same, the du should not change anymore. float get_deltau(float u, L, Peri) { float du = L / Peri; int maxcount = 10; int count = 0; while (count < maxcount) { vector A = primuv(1, 'P', 0, u); vector B = primuv(1, 'P', 0, u + du); float delta_u = L / length(A - B) * du; du = delta_u; count += 1; } return du; } P.S. it will be better to add a stop condition in the function and also apply resample on the curve. If interested here is a modification of an older experimental file of my collection. objects_along_curveC.hipnc
  9. Houdini 19 Wishlist

    now that we can resize scene view panel individually, it would be wonderful to lock views to specific node in the same network let's say I am doing some animation with some blend shapes and I have to add a new pose with a bend sop. Locking a view to the specific node can help to look at my anim in a panel with the object not in place (animated), while modifying the new pose in the original position using handles of the tool currently in use without going crazy. one more note, the red alert for the camera is cool but not enough. I still move the camera for error even if that menu is turned on. we need a cool system for camera history undos ; )
  10. Thanks for your reply. Do you know if I would I need to use nearpoints() for this and choose the last item of the array? Or is there a more efficient function to use? Everything seems to allow for a maximum search distance but not a minimum.
  11. if you have a curve you can check the distance between p1 and the points of the curve. if you resample your curve with lots of points you could select the points within some range from l, the more the points of your curve, the smaller the range you can use and the more precise it will be. You could also find more than one point on the curve that is at distance "l", in that case you should select the one with the "u" parameter closer to whatever "u" value you have at p1. You could also iteratively check if the difference between l and the distance form the world position at u value and p1 is within some range, and progressively move along the u trying to reduce that difference, But i feel this could be slow because you have to call the function to read the u value for each iteration.
  12. Hi I'm trying to make a chain of points follow a curve, maintaining the distance between them. I can achieve this in a rough way by using primuv/ primitive attribute in vops and offseting the U value by the distance. However this doesn't preserve the length L, due to the curvature. How would I find the 'chord' points of the curve along the vector P1P2 ? Another way to think of this would be the intersection of the curve and a sphere of radius L. Are there helper functions already part of Houdini that will allow me to do this? Thanks
  13. particle "beam"

    Did you manage to make this scene work in Hou 18.5?
  14. 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?
  15. How to create this line sim?

    Old saying "It is not to whom it is said, but to whom it is destined"..If you Don't See ...Next Time
  16. How to create this line sim?

    yes,thanks but this topics could not get me what I wanted.
  17. How to create this line sim?

    @mohammadmolanejad here you have Particles Just Play and Investigate
  18. @BenWall Hm near-point-Function Maybe . strange_densityDnerpoint.hiplc
  19. Narrowing it down to avoid vex errors with a distance check, I still get the error float dist = distance(@P, point(1, 'P', 0)); float d; if(dist < chf('max_dist')){ d = fit(dist, 0, chf('max_dist'), 1, 0); d = clamp(d, 0, 1); d = chramp('gamma', d); f@density = d; }else{ f@density = 0; }
  20. Hi, i think it's just volume visualization node's viewport visualisation imprefection.
  21. Not sure I understand your question. I used fit() in order to use chf("max_dist") and invert the values at the same time. Is there a better way to do this?
  22. Fit Function.. You have Reverse Or?
  23. Hey there, After spending a fair amount of time on SOP and VEX, I'm now learning basic volumes handling. I found a behavior I don't really understand and can't find any ressources on the subject. I created a simple setup to change the density of a scalar volume with the distance to a point. Everything works as expected, but when I move the point to a bound of the volume, the density from on side seems to be "reflected" on the other side of this volume. Looking at the screenshot, we should only get yellow values on the left (where the point is), the right side should be blue. Seems to me there are three possibilities here: - My volume wrangle might be wrong, - There is something I didn't understand about volumes, - There is something wrong with the way I setuped the volume visualization. Can someone explain what I didn't get right? Thanks strange_density.hip
  24. Hi guys, I have a problem with the compile block inside HDA. I is working fine unless I add a second asset right after the first one. Then things go crazy because this second asset claims that the Stroke Node that is not even in the first compile block is not Compile compatible and it cannot cook. Should I isolate the stroke from the compile block? Tom
  25. How to create this line sim?

    hi I hope you are well. I'm studying this project from Ben Watts and I need help. I wanted to know how the simulation of these lines is done?(00:05) thx.
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