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IhabAli

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About IhabAli

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  • Name
    Ihab Ali
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    Canada
  1. Hi, Wondering why when the an incoming velocity field to a dop simulation doesn't "move" while being self advected unless there is a project non-divergent in the sim. In a barebone smoke sim, I can advect incoming scalar fields using a velocity filed imported from SOPs, but when I try to advect the velocity field by itself, the velocity field doesn't seem to move inside the smoke object container. Regards, IA
  2. I actually found the culprit right after I submitted my reply HDR textures under 3D was not set to full HDR (it was at 8bit). For some reason that displaying banding with this particular attribute sampling method.
  3. Thanks JO. Not much going on with import point it's basically just the point() vex snippet and I'm retrieving the attribute I need. Mantra appears to render this smoothly but the view port would also render smoothly a volume that is sampled directly from the position of the voxel(e.g. with a volume wrangle or vop that basically does @density=@P.y in the case of my example) I'm not sure I understand why this particular method of sampling the attribute and assigning to the voxel causes view port issues.
  4. Hello, I'm trying to build a setup that would move volumetric noise along the spine of a sweep object, effectively changing the coordinate system of the noise to be based on an object, at least in 1 axis. I set this up using the following simple network: Inside the volume VOP I'm finding the nearest point to the voxel and getting its curveu parameter value Problem is I'm getting this strange quantization in the volume for some reason Even through the curveu on the points appears smooth: I checked 3D texture and visualization settings but they don't seem to have any effect so I'm fairly certain this is not a viewport issue. Any idea what's happening? Regards, IA
  5. HDA Viewer state node?

    Hello, I'm trying to create a digital asset that allows the user to user a paint curves on the surface of the input geometry. How would I set the the viewer state of the HDA to that of the paint node inside in the HDA's network? Thanks!
  6. Is it possible to simulate aerodynamic lift generated by vellum patches moving in “air”? In C4D there is a little option under soft body dynamics that emulates the effect of lift but I'm not sure how to do that with Vellum in Houdini.
  7. Hi, I have a file cache in a scene and for some reason when I try save to disk in background it terminates prematurely without writing any files. When I run it using “save to disk” it works perfectly fine. How can I find out what's happening when it's running in the background? are there any log files produces for the “hbatch” command? Regards, IA
  8. Vellum intersections upon instancing

    In case anyone is interested this is my temporary fix to the issue so that my patches don't stick together: I added a pop wrangle node after my vellum source to make sure this is the last step of the sim. Inside this is what I have if(@overlap_self>0&&@overlap_self<999) { @disableslef=1; } else { @disableself=0; } basically disables self collision if an overlap is detected...at least this is how I understand it. it seems to work..
  9. Hello, i have a setup using instancing from the vellum source node. I’m essentially using single point each frame to instance a vellum patch. The trouble is, if the instance happens to be created intersecting with an already instanced patch the they seem to weld together. It’s not actual welding but I think the collision algorithm just gets confused and keeps the overlapping surfaces stuck together as it tries to minimize intersections between the pscales of these points. Is there anyway to resolve that?
  10. Hi, Struggling a bit to understand what's going on with quaternions and rotations but I'm basically trying to get a particle to point at its direction of motion in general but to constantly rotate around a certain predefined local axis. In the attached example I'm establishing orientation based on the velocity and setting up constant rotation relative to an object's coordinate system. All seems fine until the particle changes velocity using the pop wind. Not sure what's happening with rotations at this point, it seems to be working but things seem to jump abruptly at certain points. I'm guessing this has to do with matrix rotations but I'm not sure I fully understand the issue or how to fix it. particledirection.hipnc
  11. Sweep multiple curves?

    Your example sort of shows what I'm talking about but imagine the cross section wasn't a simple circle, what if I wanted to sweep the cross section formed by the two shapes below along a curve/line? The second image is basically the outline of the shape after individually sweeping/skinning but I need to somehow procedurally bridge the outer and inner walls. My boundary edge group->polybridge trick no longer works in this case because the edges don't match between the inner and outer wall(as seen in the 3rd picture).
  12. Sweep multiple curves?

    Hi, I'm new to modelling in Houdini and I wonder if there is a straight forward way to sweeping a cross section made of multiple closed curves to essentially create a thick and concave cross section. So for example sweeping two circles on a line to make a tube with thick walls. In C4D for example, connecting two such closed curves and running it through the sweep would automatically do that but in Houdini the only way I'm able to do that is to sweep each curve separately, create boundary edge groups for each resulting skinned sweep, then polyfill between the boundary edge group. Seems like a lot of nodes for a simple task Regards, IA
  13. Fuse SOP 2.0 No unique?

    How did I miss that!! thank you!
  14. Hi, In H17.5 the fuse sop has been replaced by a new one that doesn't have the unique tab any more. Any ideas on how to recreate the same feature using other SOPs? basically a way to split vertices that have common points and generate new points. Regards, IA
  15. Hello All, I know this probably doesn't exist, but I have an algorithm that can be implemented a lot more efficiently if I'm able to write data to voxels other than than the one the current voxel in a Volume VOP/wrangle. We can obviously sample other voxels from any file or volume primitive but how do we write to these voxels?? My current solution is to create another volume of identical size and resolution and use it to "mark" that the primary voxel needs to be modified, obviously this decreases the efficiency of the code as now I'm iterating across all voxels twice. Rega
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