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Found 11 results

  1. Colozize SDF

    Hi there! I'm looking for a method to colorize SDF (VDB) based on an attribute, which I made, for ie: the distance along the X axis. (The surface created at render) Any help would be appreciated.
  2. Hello, I am creating sdf vdb volume from polygons. I need filled interior, because later on I will sample those values. However I would like to process my volume a bit, for example smooth, dilate etc. After those operations interior voxels are lost, only area close to the surface contains voxels. Is there a way to get those values back? Thanks, Juraj
  3. Kill particles with SDF

    Hi everybody, I'm currently working on an effect in H14. I am attempting to have particles die when they collide with an SDF/VDB object. I have been using the collision detect node with the collision target set to DOP objects pointing to my static object collision node. However, it doesn't look like it works. The same collision detect does work with a SOP poly object. Is the collision detect node working with SDF's/VDB's? Cheers.
  4. I was looking into sdf and i found this file from Chris. I slightly modified it to get points colored by a ramp using sdf Does anyone know a better way to do that, in a normalized kind of way? I would like not to have to use the fit range to adjust the color ramp. Later i want to use this method to create custom velocity field on a pyro sim to contain the smoke within the velocity field. Thank you Fred sdf to point color.hip
  5. SDF Collision with smokesolver

    Hi guys, I'm doing a dust simulation using smokesolver. I used a VDB from polygon sop and created a SDF version of my deforming, collapsing building for collision object (volume sample). The problem is the SDF collision just clears the smoke when they are colliding and doesn't change the flow at all. I tried to create a sample hip but it seems correct with a simple box. Did anyone have the same experience before? and I should mention that my SDF resolution is enough and. Thanks for noticing
  6. SDF Blending

    Levelsets In Production: Spider Man 3 / SDF Blending http://www.jcohen.na...elsets_2007.pdf I've been passing this hip file around, so thought I'd just put it up in the forums GWsdfBlending.hipnc
  7. Hi, recently I am facing this issue. The display of sdf and distance vdb is always corrupted in the viewport. I've attached an image. Does anyone know how to fix this?
  8. Hello everyone, I have some serious problems with the simulation time of my Smoke. Suddenly, from frame 69 to frame 70 the SDF calculation for the density source is taking for ever. But there are no major changes in the source geometry. The normal SDF calculation time ranges between several seconds but starting at frame 70 it takes 20min plus. (The source is the geometry from a fractured bulding) Where sould i start to look for a solution? Thank you in advance, Lukas
  9. Hello everyone, Came across a couple (probably) very simple questions regarding the use of GU_SDF and GU_SDFParms today that I'd be grateful if anyone could shine a light on. The first issue I had was in thinking that the SDFParms::setOffset() method would behave similarly to the corresponding parameter on the IsoOffset SOP. In my attempts to use it, however, it doesn't seem to alter my volume. In the most basic situation of creating a single SDF from geometry, my assumption is that I would just need to set the desired properties (including the offset) using the GU_SDFParms class, and they would be respected during the GU_SDF::build and/or getFunction() calls. For example: gdp->getBBox(&bbox); GU_SDF sdfVol; GU_SDFParms sdfParms; sdfParms.setMode( GU_SDFParms::RAY_INTERSECT ); sdfParms.setDivisions( 60, 60, 60 ); sdfParms.setBBox( bbox ); sdfParms.setLaserScan( true ); sdfParms.setFixSigns( true ); sdfParms.setOffset( -0.25f ); // This line doesn't seem to matter, but I wish it would! sdfParms.setSweepCount( 3 ); sdfParms.setSweepThreshold( 2.0f ); sdfVol.build( gdp, sdfParms ); gdp->clearAndDestroy(); GU_PrimVolume *volumePtr = (GU_PrimVolume *)GU_PrimVolume::build( gdp ); volumePtr->setVoxels( sdfVol.getFunction() ); This works as I expected with many of the parameters, but regardless of what I drop in the setOffset method my iso contour is still displayed at 0 in Houdini. Any idea why this would be the case? On the subject of setOffset(), I'd be curious to know the difference (if any) between GU_SDF::setOffset() vs GU_SDFParm::setOffset(). Is it just as a convenience to allow for sharing GU_SDFParm objects but overriding particular GU_SDFs? And a bonus question! There are three modes for converting volumes to SDFs. GU_SDFParms::VOLUMESAMPLE and GU_SDFParms::VOLUMESAMPLEANDREBUILD are outlined on the IsoOffset help card, but does anyone know what GU_SDFParms::VOLUME mode is expected to do? Thanks in advance, and sorry if it's something obvious... stumbling through bit by bit!
  10. I am trying to access the data in a VDB sdf volume container that I use as a 3rd input in my node. I managed to install the openvdb headers and everything seems to compile just fine. All I'd like to do is basically access the distance and gradient values in the vdb sdf, given a world space position. I found this beautiful method which seems to address the gradient question... UT_Vector3 GEO_PrimVDB::getGradient ( const UT_Vector3 & pos ) const And this is the code snippet I am using: GU_Detail *sdfInput = new GU_Detail; duplicateSource(2, context,sdfInput); GU_PrimVDB myVDB(sdfInput,0); UT_Vector3 samplepos(1.0,0.0,0.0); UT_Vector3 gradient; gradient=myVDB.getGradient(samplepos); // <--- CRASH [/CODE] ... but when I try to use it , Houdini crashes (it crashes only on the line where I use getGradient method, it doesn't crash when I define *myVDB) I couldn't find the method to access the distance value by the way. I am pretty sure I am doing something terribly wrong cause of my limited c++ knowledge Can someone help me to correct the above code snippet and add the method to access the 'distance' data ?
  11. I am trying to create a simple shader that maps the distance from an object to the red channel. I have a plane I assign the shader to. I have a torus converted to SDF. In the shader I convert P to world space, then use a "volume sample from file" to sample the rendered pixel from the SDF and feed the result to the red channel of my diffuse color. In order to specify the 'file', I use this code op:`opfullpath("/obj/geometry/OUT_SDF")` When I render i just get a black frame. The geometry is there cause i can see the alpha of the plane, but apparently nothing comes out from that "volume sample from file" node. I wonder if it's possible to fetch sdf data directly into a shader. I attached the hip file to illustrate my issue. p.s. I don't want to use an attribute transfer approach in SOP land cause I want to maintain the 'pixel' level resolution in my shader, and don't want to rely upon the resolution of my plane. Any idea ? proximity_shader_test.hip