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Everything posted by woodenduck

  1. simple vex question

    I think it's because "id" is recognised automatically in vex as an integer attribute. As the rand() function returns a float, this gets truncated, resulting in 0. If you explicitly cast your "id" attribute as a float, I think you'll get what you're after. Try f@id = rand(@ptnum); The reason it works for @myId is because user defined variables default to floats if not explicitly cast. If you change it to i@myId = rand(@ptnum) it will return 0 for the same reason as stated above. Hope that helps. Cheers, WD
  2. Alembic Motion Blur

    Have you checked the "Geometry Velocity Blur" box on the sampling tab of your geometry object?
  3. If all you want to do is fade the colour over time, I would just multiply @Cd by a value less than 1 each frame. Otherwise you will need to compare the attribute value on the current frame with the previous frame. If the value on the current frame is 1 and the previous frame is 0, then you can store @Frame/@Time in a variable as the infection frame.
  4. Animated texture sequence turns pink

    How about collapsing your shader network in to a material and promoting the parameters there.
  5. In order to get the normals correctly oriented you need to calculate them before the scatter. This is because the orientation of the polygons associated with a given point determine the normals direction.
  6. if you add some point normals to your grid before the scatter and ray, you will see spheres correctly oriented. Cheers, WD
  7. Access sop parameter within popnet ?

    You can use a channel expression - ch("../../path/to/parameter")
  8. Take a look at this - http://tmdag.com/vopraytracer-pt1/
  9. You can resume simulation from .sim sequence.
  10. Particles won't emit (H15.x)

    Go inside your popnet, on the popSource node, inherit attributes parameter. By default this should be set to '*' but on yours it is empty. Just pop a '*' in there and you're good to go.
  11. extra tokens in expression

    Try separating with "" and + so your expression would become... ch("../../../img/comp1/default_pic_"+opdigits(".")+"/size1")/200
  12. Pyro velocity field question

    You could add a GasFieldWrangle piped in to velocity update with @vel *= 0.9; in the vex snippet parameter. You could add a gasFieldVop piped in to velocity update. Bring the vel field in with a Bind Vop and multiply 0.9 (or whatever drag rate you want) before adding a bind export set to vel. You could add a gasDamp Dop. This would also get piped in to the velocity update input on the pyro solver. You could also try playing with the viscosity parameter. This has the effect of blurring out the vel field which will give you a kind of drag. Depending on what you are trying to achieve.
  13. emit particles from pyro sim

    You can use a Scatter Sop on a density field, then source you particles from there.
  14. Using Bend in Houdini

    lay down a 'transform' sop. Hit tab and start typing transform. From here you can move you tube where you want. Then lay down a 'merge' sop. Plug the output of the transform AND the output of the node BEFORE the transform in to the merge. You should now have two tubes in different positions.
  15. Using Bend in Houdini

    Start with a curve. Click the curve tool from the 'create' tab at the top. Then click in the viewport to start creating a curve. Once you have something close to the shape you want (you can push and pull the individual points around by clicking on them and hitting 't') you can then append a 'polywire' operator to your curve. This will create a tube based on the shape of the curve you use as an input. You can increase the 'segments' and 'divisions' parameters to get a smoother tube. Enjoy!
  16. You can bring vel in to a volume vop using a 'bind' vop. Name = vel, type = vector. Do whatever operations you want on it then you can use 'bind export', again set to name = vel and type = vector.
  17. POP inherit point normal from passing a point

    You will need to set the 'radius' and 'maxpoints' channels to something useful... ;D
  18. POP inherit point normal from passing a point

    Try this in a popwrangle inside the popnet. if(@n2 == 0) { float radius = chf("radius"); int maxpts = chi("maxpts"); int handle = pcopen(1, "P", @P, radius, maxpts); v@n2 = pcfilter(handle, "N"); v@N = @n2; }
  19. magnet point snap align

    Is your geometry packed?
  20. Copy geos on grid with random position and rotation

    45 * @ptnum
  21. attrib wrangle set to run over prims... addpoint(0, @P); removeprim(0, @primnum, 1);
  22. Need advice from Houdini users.

    In my experience, the best way to revise your math is to use Houdini ;D
  23. staggering a carve by primnum

    Hit "create meta import node" on "foreach begin" to allow access to the iteration attribute. Then add the following in to the second u parameter of the carve sop: clamp((1-$T)+(detail("../foreach_begin1_metadata1/", "iteration", 0)/2), 0, 1) Should be good, providing your metadata node is named the same.
  24. Is this in a Wrangle? Has forcescale been declared anywhere?
  25. VDB Cloud

    On the top right of your viewport above where you select your camera, there is a drop-down menu. You can choose how all geometry is displayed. Set to "shaded bounding box". If you wan to control the display per-object, you could use a "bound" sop and set the blue display flag on, while keeping the purple render flag set to the original geo.