Found 5013 posts.
Search results Show results as topic list.
Technical Discussion » How to move a points along curves in world units?
-
- tamte
- 9078 posts
- Offline
you can use primuvconvert() [www.sidefx.com] VEX function to convert real distance value to parametric 0-1 coordinate
Technical Discussion » Difference between copying to points on polygons and not
-
- tamte
- 9078 posts
- Offline
AnsonSavageyes, many geometry operators use implicitly computed normals from polygons when they are not explicitly defined by an attribute
Are they implicitly created and read in the process of copying to points?
Edited by tamte - 2023年7月13日 14:40:34
Technical Discussion » object merge using the output of another node
-
- tamte
- 9078 posts
- Offline
not sure if there is a general syntax to get it directly, but you can dive into groomfetch and see which node is passed to second output and object merge that one
so in your case:
but as I mentioned, "output2" is the name of the node inside of groomfetch, not a generic getter to the specific output of the node
hair generate for example has second output node named "OUTPUT_SKIN" so it would be
etc...
so in your case:
../groomfetch1/output2
hair generate for example has second output node named "OUTPUT_SKIN" so it would be
../hairgen1/OUTPUT_SKIN
etc...
Edited by tamte - 2023年7月13日 11:46:51
Technical Discussion » Pyrobake to Cd
-
- tamte
- 9078 posts
- Offline
check Bindings/Bake Emission Volume
and in attribfromvolume1 specify Ce in Volume parm
you may need to blur or expand the volume values a bit
and in attribfromvolume1 specify Ce in Volume parm
you may need to blur or expand the volume values a bit
Technical Discussion » A smarter way to pause and resume caching?
-
- tamte
- 9078 posts
- Offline
from the description of the Deadline approach it looks like it will still need to keep the sim fully in memory and can potentially just free up some CPU resources, so for heavy sims that may be a no go, unless you just need to perform low memory tasks while the sim is on low CPU
On top of that it doesn't protect you from crashes
so checkpoints may be a safer way and also the only way I know that should allow you to truly resume the sim, even though I didn't have a need to use them in production, so not speaking from experience, but just in how I understand it should work
the .sim files may be heavy, but you may need to keep only 1 last rolling frame on disk at a time so it may be worth for long sims
and you can always combine the techniques, that way you can use deadline or other scheduler if it allows you to decrease the resources on the fly but you can also kill the job if needed if you are checkpointing and then submit from that frame later
On top of that it doesn't protect you from crashes
so checkpoints may be a safer way and also the only way I know that should allow you to truly resume the sim, even though I didn't have a need to use them in production, so not speaking from experience, but just in how I understand it should work
the .sim files may be heavy, but you may need to keep only 1 last rolling frame on disk at a time so it may be worth for long sims
and you can always combine the techniques, that way you can use deadline or other scheduler if it allows you to decrease the resources on the fly but you can also kill the job if needed if you are checkpointing and then submit from that frame later
Edited by tamte - 2023年7月10日 12:18:33
Technical Discussion » A smarter way to pause and resume caching?
-
- tamte
- 9078 posts
- Offline
The only way I know to resume sim after the crash or deliberate kill on the farm is to cache checkpoint files alongside
https://www.sidefx.com/docs/houdini/dyno/cache.html#explicit-dop-disk-caching [www.sidefx.com]
You can play with Checkpoint Trail Length and Checkpoint Interval to save only small amount of trailing .sim filés exactly for the purpose of resuming
While you still filter down the sim data and save normally as bgeosc or other format
https://www.sidefx.com/docs/houdini/dyno/cache.html#explicit-dop-disk-caching [www.sidefx.com]
You can play with Checkpoint Trail Length and Checkpoint Interval to save only small amount of trailing .sim filés exactly for the purpose of resuming
While you still filter down the sim data and save normally as bgeosc or other format
Edited by tamte - 2023年7月8日 11:52:47
Technical Discussion » How to Render Coloured Packed Objects in Mantra w/o unpack?
-
- tamte
- 9078 posts
- Offline
in the shader you can access any attribute that lives on packed primitive geo using Render State VOP with packed: prefix like packed:Cd (see attached file)
or if using Principled shader and want diffuse Cd or opacity Alpha, just check Packed Color or Packed Alpha
you can also use Material Stylesheets for more complex overrides
or if using Principled shader and want diffuse Cd or opacity Alpha, just check Packed Color or Packed Alpha
you can also use Material Stylesheets for more complex overrides
Technical Discussion » IntersectionAnalysis: Collected Attributes don't make sens? {[SOLVED]}
-
- tamte
- 9078 posts
- Offline
Can't check right now, but I believe intersection analysis expects triangulated geo, and if it's not then it triangulates internally
Therefore the numbers may refer to the triangulated prims
(There is a warning on your node which probably says something along those lines)
So try adding Divide SOP to triangulate before and see if the numbers match
Therefore the numbers may refer to the triangulated prims
(There is a warning on your node which probably says something along those lines)
So try adding Divide SOP to triangulate before and see if the numbers match
Houdini Lounge » Opengl to attributes
-
- tamte
- 9078 posts
- Offline
Fx_enjoyerYou may be referring to sensor nodes and vex functions, like sensor_panorama_create, etc..
I vaguely remember that there used to be a vop or possibly vex function to render opengl views from an agent’s viewpoint but I can’t find it again.
https://www.sidefx.com/docs/houdini/nodes/vop/sensor_panorama_create.html [www.sidefx.com]
https://www.sidefx.com/docs/houdini/vex/functions/sensor_panorama_create.html [www.sidefx.com]
Edited by tamte - 2023年7月6日 01:14:24
Technical Discussion » vellum cloth/hair collisions misery
-
- tamte
- 9078 posts
- Offline
- you are using output of your cloth sim as a collider, therefore it will not be affected by anything
collider is there purely for active vellum objects to collide with
- if you don't want hair to penetrate through make sure there is some gap between the cloth and ground so that the hair can bend and fit in there
- or if you want them to mutually interact you need to sim them together using a single solver
also additional things that may be causing further issues:
- your hair is extremely thin overall, doublecheck the thickness by displaying vellumhair1 with Visualize Thickness on or also vellumsolver2/Visualize/Thickness
ideally it would also not taper to infinitely thin tip
- vellumsolver2 has extremely high gravity for the scene scale, your grass geo seems in meters so I'd suggest keeping gravity at default
that will also allow you to use much lower bend stiffness and not be getting jagged shape on your grass
- maybe you can reduce the segments of your simulation version of the grass if you are aiming for higher stiffness, just to speed up the sim
collider is there purely for active vellum objects to collide with
- if you don't want hair to penetrate through make sure there is some gap between the cloth and ground so that the hair can bend and fit in there
- or if you want them to mutually interact you need to sim them together using a single solver
also additional things that may be causing further issues:
- your hair is extremely thin overall, doublecheck the thickness by displaying vellumhair1 with Visualize Thickness on or also vellumsolver2/Visualize/Thickness
ideally it would also not taper to infinitely thin tip
- vellumsolver2 has extremely high gravity for the scene scale, your grass geo seems in meters so I'd suggest keeping gravity at default
that will also allow you to use much lower bend stiffness and not be getting jagged shape on your grass
- maybe you can reduce the segments of your simulation version of the grass if you are aiming for higher stiffness, just to speed up the sim
Technical Discussion » VEX code for scaling pscale per point per time step
-
- tamte
- 9078 posts
- Offline
Dave_ahyou forgot @ to bind to pscale attributetamtepscale *= .9 ;Dave_ahso why wouldn't you try the same? (instead of trying == which is comparison of equality and not an assignment)
For Maya users equivalent MEL code would be
pscale *= .9 ;@pscale *= 0.9;
assuming you run it in DOP environment, like Solver SOP or directly DOP net
Does not work in SOP level pointWrangle and attributeWrangle SOPs. Houdini generates syntax error and bypasses the SOP node.
here is an example in plain SOPs where this will be applied once to incoming value
and also inside of Solver SOP where it will be applied every timestep
Technical Discussion » cop2 in sops: can't get detail value correctly in SOPs level
-
- tamte
- 9078 posts
- Offline
Technical Discussion » cop2 in sops: can't get detail value correctly in SOPs level
-
- tamte
- 9078 posts
- Offline
COPs often treat the input stream as a sequence of frames at constant resolution and therefore size parameters can't be time dependent
however you should be able to use TOPs to generate independent workitems that execute your COPnet with desired size overrides
however you should be able to use TOPs to generate independent workitems that execute your COPnet with desired size overrides
Technical Discussion » VEX code for scaling pscale per point per time step
-
- tamte
- 9078 posts
- Offline
Dave_ahso why wouldn't you try the same? (instead of trying == which is comparison of equality and not an assignment)
For Maya users equivalent MEL code would be
pscale *= .9 ;
@pscale *= 0.9;
assuming you run it in DOP environment, like Solver SOP or directly DOP net
Edited by tamte - 2023年7月3日 01:39:17
Technical Discussion » copy original start point attribute to find shortest path
-
- tamte
- 9078 posts
- Offline
There is a Start Point Attribute parameter, which can create prim attribute containing the start point number on your paths
Then you can use that in Point Wrangle to get any attribute from original geo from all points of the path
or in Prim Wrangle and then Attrib Promote to points
Then you can use that in Point Wrangle to get any attribute from original geo from all points of the path
int pt = prim(0, "startpt", @primnum); f@pscale = point(1, "pscale", pt);
or in Prim Wrangle and then Attrib Promote to points
f@pscale = point(1, "pscale", i@startpt);
Edited by tamte - 2023年7月3日 01:34:33
Houdini Indie and Apprentice » Surface tension is zero if the position of particles is zero
-
- tamte
- 9078 posts
- Offline
don't det me wrong, sampling the closest particle attributes to the current voxel may still be handy when basing surfacetension on different particle attributes, or alternatively rasterizing them to field first and sampling that
all I'm saying is that there is no need to care about particle positions in this case, since the surface tension is at voxel level and voxels have roughly the same position as average position of particles within that voxel
so I just assume that OP's description using particles just stems from assuming that it's particle based
all I'm saying is that there is no need to care about particle positions in this case, since the surface tension is at voxel level and voxels have roughly the same position as average position of particles within that voxel
so I just assume that OP's description using particles just stems from assuming that it's particle based
Houdini Indie and Apprentice » Surface tension is zero if the position of particles is zero
-
- tamte
- 9078 posts
- Offline
animatrix_
Hi,
If you bind the first input to Geometry, you can do it like this:int pts [ ] = pcfind ( 0, "P", @P, 10, 1 ); vector p = point ( 0, "P", pts [ 0 ] ); float tolerance = 0.01; if ( abs ( @P.y ) < tolerance ) @surfacepressure = 0;
since "surfacepressure" is a float field instead of attribute, only last 3 lines are all it takes
no need to deal with particles at all or bind anything to Geometry a Gas Field Wrangle binds to fields by name automatically
however tolerance should be high enough to include voxel center positions of at least first few voxel layers from the ground to get noticeable effect
or if you want some falloff you can do this
float height_min = 0.1; float height_falloff = 0.1; @surfacepressure *= fit(v@P.y - height_min, 0, height_falloff, 0, 1);
Edited by tamte - 2023年7月1日 04:29:09
Houdini Indie and Apprentice » Set Attribute Value based on ID when PTNUM change VEX
-
- tamte
- 9078 posts
- Offline
if you want to get attribute by id (default) from second input you can just do
that would however set attribute on points that don't find corresponding id in second input to 0
so if you for example want to preserve input value for points that don't find match you can do
f@mask = f@opinput1_mask;
that would however set attribute on points that don't find corresponding id in second input to 0
so if you for example want to preserve input value for points that don't find match you can do
int pt = idtopoint(1, i@id); if (pt != -1) { f@mask = point(1, "mask", pt); }
Houdini Indie and Apprentice » Decals orientation to follow AO direction
-
- tamte
- 9078 posts
- Offline
Solaris and Karma » Karma - Turn Off Self Shadowing On Particular Objects
-
- tamte
- 9078 posts
- Offline
mestelathat's not the same as turning off self shadowing though, since such object will not cast shadows to any object and will also not appear in any of the secondary rays
Setting its render visibility to primary will mean it won't cast shadows, but will still receive shadows.
proteanthis is closer, but it will still not cast shadows on any other objects
Or -shadow also works if you want it visible in indirect
so it would still be handy to be able to turn off self shadowing only, but still cast shadows to other objects and appear in other secondary
or for that matter to be invisible to any specific secondary self hit
I guess what would need tracesets to be able to exclude self
Edited by tamte - 2023年6月27日 01:14:00
-
- Quick Links