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Found 6 results

  1. Hi After reading this article on scratchapixel, where they talk about an efficient algorithm for finding intersections of a ray and a box I wanted to see how it compared to the built in intersect function. To my knowledge, the built in intersect function is looping over all the prims given in no particular order - I infer this information from the description of the primfind function, which states that it should be used with intersect, because"primfind uses an underlying tree structure to speed up search" (so I take it intersect does not). My test scene creates boxes on n scattered points in a volume. On one attribute wrangle I use the built in intersect function, on another one I use the one from scratchapixel. I would expect the scratchapixel one to be faster, also because the intersect has to loop over n * 6 prims (6 prims per box) whereas the scratchapixel one only has to iterate over n points. However the intersect is magnitudes (!) faster than the custom one. Does anybody have ideas why?
  2. Hi, I'd like to sample the UVs and texture from the models i intersect with but don't know how... Any advice ? Thanks Escherisation.hipnc
  3. Hi, is there a faster way to check 10000+ objects for some attributes? Im making a tool that uses intersect_all() I want to make a tool that looks at the objects and see if it is visible by the camera position. And if it isnt, it can be delete the object ( not only the prims or points). So what I did now is to give it a color promoteToDetail in a for each to MAX and promote it back down to have the object the max value. But is there a better and quicker way if there are so much objects? thnx
  4. Hi, How could I measure vector distance to another surface like you see here. Not just closest point distance, but distance following the vector. I would like to use this as length point attribute in hairgen to control the shape of groom with geo. Cheers Janis Vector_length.hip
  5. Baking Normal Distance to Zero Thickness

    Hi! Can anyone point me in the right direction for how to determine on air-tight geometry the distance it would take to push each point inward along the normal (like the Peak nodes does, if you give it negative numbers) until it hits the other side, getting pushed in at the same rate? Right now if you use the Peak node with negative numbers of increasing magnitude on a mesh that has parts of variable thickness, the thinner parts will eventually start turning inside-out. What I want is for them to stop right before that happens and stay at a thickness of zero, so they squeeze down to invisibility, while the thicker parts of the mesh continue to push inward. Specifically what I need is a value that is that distance, which I can transfer over to vertex colors, because this is for a game asset where the actual squeeze along the normal direction will take place in the game engine, not in Houdini, and I need a value to clamp the push distance for, on a per-vertex basis. Thanks!
  6. I have a RaySOP that is doing exactly what I want. It is shooting rays per point along a direction defined by point attribute 'rdir' and is returning the hitprims I'd expect. Hitprims are the green numbers in the images below, yellow lines are visualisation of attribute 'rdir' (raySop shown below) I want to be better about doing things with VEX so I tried doing the same thing with the same set of points, with the same 'rdir' attribute and same collision geo. I get wildly different results for my hitprims as shown below. heres the tiny bit of VEX I've got: vector p; vector hitprimuvw; vector dir = @rdir; int hitted; hitted = intersect(1, @P, dir, p, hitprimuvw); @hitprim = hitted; What am I missing?