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Josami

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About Josami

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    Jos
  1. create interactive Fog

    Hello angeldev, How are you trying to approach this? You could use collision inside a smoke solver.
  2. Problems with dandelion wire sim

    Ok, I think I found the answer to all the questions. 1.- The forces are being applied at all time, but the speed of the movement makes it difficult to notice. I slowed down the simulation using a Retime node and a Polywire, and the noise is there. A SOP alternative to intensify the vibration could be adding more noise over the rest position of the probes, but I think that won’t be needed. 2.- This one has to do with the force and the frame when the objects are released. In frame number 0 of the “dopnet4”, all the seeds have a pintoanimation value of 1. However, in the next frame, where the seeds are modified by the forces, that value has already become 0. I think the starting frame of the sim is used to feed the solver, so it makes sense to me that the next frame is some kind of stabilized version of frame zero, that is now being affected by the forces. That being said, if you want to keep the modified shape of the seeds you also have to keep the “Solve on Creation Frame” box on the Wire object checked. Otherwise, they will jump back to their initial state, despite of the threshold being reached. 3.- You can animate forces if you change the Default Operation from Set Initial to Set Always. There’s more information in the next link: http://www.sidefx.com/docs/houdini/dyno/top10_medium.html#set-initial-vs-set-always 4.- As I said, I think the starting frame is used to load the object and forces. The noise in my example is due to “noise wind”. Once the sim really begins, everything behaves as it should.
  3. Problems with dandelion wire sim

    Hi! Hope everyone's doing great. I've been working on a dandelion scene, but I have some questions about the simulation itself. Hopefully, someone could help me figuring this out. My setup feds some procedurally generated seeds into a wire simulation. The attributes klinear and kangular are already set in SOPs. Inside DOPs, several forces nodes try to replicate the behavior of the wind. To release the seeds, a Sop Solver compares how much force are receiving the constraints, with a threshold. My questions are: 1.- While the seed is still attached, you can see every prob vibrating because of the “noise wind” node, but once it is released, the forces seem to act over it as a whole. It still moves around, but freezes in its last position. Do you know how I can get all my forces affecting the seed all the time? 2.- Well, the seeds are flying in the same position. Ok, they are moving fast and still rotating so it is not that noticeable. The problem is the last position is different depending on the amount of force received or the time when the seed is freed — I don’t know which, but I think is the first one. That’s kind of obvious, but let me explain. In “dopnet4”, seeds are released at the very beginning. I used two time shift nodes to show how the position of an arbitrary selected seed is affected by the forces, but jumps back to its original state after being released. However, in “dopnet5”, where the seeds are released at the end of the sim, that selected seed behaves as it should and both positions are the same. Do you know why is this happening? 3.- Can you animate forces inside of DOPs? Right now I’m using a vector field to prevent the wind nodes from reaching their goal position. That way the objects keep moving. Maybe there’s a better solution I’m not seeing at. 4.- My simulation starts at frame 0, before my scene begins. That’s because the start frame of all the wire sims I did was weirdly shaped. Maybe the solver needs an initial frame in order to properly load the object, but I was wondering if that’s the reason, or if there’s a proper way of solving it — assuming it is an issue. The “frame_0” nodes show what I’m talking about. Here is the folder with the sim nodes and the baked geometry. It would be amazing if some of you know the anwers. Thank you very much! DANDELION_TEST.rar
  4. Light data to generate geometry

    Thank you very much for your answer konstantin! It was really helpful. I’m thinking of using that shadow as a vector source to modify particles emitted from the character’s body. However, the shadows I'm trying to use are the ones cast over the character's body — didn't explain myself. Based on your sample file I came across the idea of using an external geometry point as a fake light object, using its position to calculate the dot product. Just have to set a normal in the same direction the spotlight is pointing, and reference its position. It's a pretty basic and common setup, but maybe someone finds it useful. FAKE_LIGHT.hiplc
  5. Hello! I've been trying to get light data in some attribute or texture in order to use the shadows to generate geometry. Until now, the best approach has been baking the light as a texture and loading it using Attribute from Map. However, the baked texture works only if the character is static. What would be the best approach to cache or cast lighting data in order to procedurally generate geometry? A shader, maybe? Thank you in advance.
  6. Music Visualisation

    I found your experiments both beautiful and inspiring. Thank you for sharing your website :).
  7. Hello to everyone! I'm fairly new to Houdini and to vfx at all and been struggling trying to do this by trial and error and searching in forums. Even though I have learned a lot by doing that, I think it's better to ask for someones help. I want to create some dust clouds (like a small dust storm) for a shot. Because the area that I'm trying to fill is big and my resources are limited, I thought it would be a good choice trying to achieve the effect using SOPs instead of a smoke simulation in DOPs. The setup related to this part of the effect is basically some boxes each modified by a Volume VOP to add some noise and animation by frame. I read that Billowy Smoke Shader can help you to get a more fluffy look at rendering. My first frame was great, but the next weren't as good because of the noise. The shader is supposed to use the rest field of your simulation to position it, but I'm in SOPs. Another user asked for something like this in the forum: He says: "just create a vector rest volume in the beginning that has the world coordinate of each voxel as its value. Be careful to do all the same advection operations on your rest volume as you do on your density volume". But I think a main difference is that they are working with shaped geometry and my whole dust storm is, well... a box. Until now my tests have been: 1.- Expose rest attribute with a wrangler before my volume vop and create a surface attribute named rest. 2.- Create it after the volume vop. 3.- Create the noisy volume, then convert it back to polygons, add a rest field and then again convert it to fog. And nothing worked. My questions are: 1.- Is there are way to use a rest field from SOP to shape noise in the billowy shader? If yes, what is it and how do you work it. 2-. Or would it be better to create a noisy volume, convert back to geometry, add pyoclastic noise and convert it back to volume? Thank you in advance. I would really appreciate your comments.
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