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Houdini Indie and Apprentice » Houdini Fur Guide Density
- derrick
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Guide density describes the number of hairs per unit area. This value and your model's surface area determine the number of generated guide hairs.
Technical Discussion » Fur Crash on H12.5
- derrick
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Technical Discussion » foreach SOP issue
- derrick
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I think there is some confusion about the behaviour of parameters on the Delete SOP. The “Filter Expression” parameter is evaluated once per element. Items will be deleted if the parameter evaluates to a non-zero value. Consider using the “Group” or “Pattern” parameters.
Technical Discussion » find out bullet version?
- derrick
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All versions of Houdini so far have only used 2.77. The version is listed on the System Requirements page: http://www.sidefx.com/index.php?option=com_content&task=view&id=415&Itemid=269 [sidefx.com]
Technical Discussion » what version of bullet with 12.1.125?
- derrick
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Technical Discussion » compiling sim_solverbullet errors
- derrick
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The Bullet Solver in Houdini 12.1.125 uses version 2.77 of the Bullet Physics library. I don't think the difference in versions is related to the error you are encountering.
The symbol should be defined by “SIM_BulletData.o”. What commands are you using to build the Bullet Solver?
The symbol should be defined by “SIM_BulletData.o”. What commands are you using to build the Bullet Solver?
Technical Discussion » Glue Bullet vs RBD problem, Instanced geo into DOPs
- derrick
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The RBD Solver is unable to enforce glue constraints between RBD Objects and Static Objects. You can work around this limitation by using constrained RBD Objects (perhaps with some RBD Pin Constraint DOPs) instead of a Static Object.
Quickly moving and thin objects are also a challenge for the RBD Solver. You may need to increase substepping to detect collisions between these objects.
If you decide to use the Bullet Solver with your scene, consider reducing the “Collision Padding” for the “As-Is” geometry representations to prevent thin features from disappearing.
Quickly moving and thin objects are also a challenge for the RBD Solver. You may need to increase substepping to detect collisions between these objects.
If you decide to use the Bullet Solver with your scene, consider reducing the “Collision Padding” for the “As-Is” geometry representations to prevent thin features from disappearing.
Technical Discussion » DOP Question.
- derrick
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Delight0092
I created a DOP network that groups the objects by time, so they drop one after another, however this cuts of at a certain point, I don't know why.
The Bullet Solver is putting the stationary objects to sleep. This can be fixed by turning off “Enable Sleeping” on the RBD Fractured Object's “Bullet Data” tab.
Houdini Lounge » Orient attribute
- derrick
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live_fx
How i can get $ORIENT ? How look right name for orient variable ?
$ORIENT0(123) don't work..
The Attribute Create SOP can be used to create variables for existing attributes. Consider appending an Attribute Create SOP with the “Name” parameter set to “orient”, the “Size” parameter set to 4, and the “Write Values” toggle turned off.
Technical Discussion » pCapt vs bonecapture
- derrick
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arctor
and can we get an explanation as to why this change was made?
it effectively makes it impossible to use geometry captured in H12 in an H11 rig (saved as hbclassic) and I don't know how to monkey with the attribute names to get it to work.
The change was necessary to fit capture weight support into Houdini's new geometry library. The translation between bonecapture and pCapt should be handled automatically when working with hbclassic files. A bug preventing this automatic translation was fixed in Houdini 12.0.579. Are you still encountering translation problems with the most recent production build?
The documentation has not yet been updated. This is a bug.
Technical Discussion » Houdini Fur
- derrick
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gregjenings
1)First as I cannot style guide curves according to my requirement procedurally ,Is there any tool which would help me style,Something similar to shave and hair option where I can style each guide curve .
2) How I can implement curves generated in other software e.g. in Maya and use those curves in houdini as my guide curves for styling.
Custom guide hairs can be used by replacing the SOP network in the Fur Object's contained “guides” network with your own SOP network. Of course, the guide hairs will have to be animated to match the character's motion.
When building a custom SOP network to define the guide hairs, ensure the curves all have the same number of vertices, have vertex numbers increasing from root to tip, and have a primitive vector3 attribute called “guideorigin” indicating where each hair belongs on the character in its rest pose.
gregjenings
3)I am also facing some issues with Houdini's bend option present in Fur menu.
a) When I paint bend some Fur moves in other direction irrespective of that fact whether I have reflection On or Off.
b)Also when I change some brush properties guide curves moves unexpectedly they should be remain stable to the last setting unless I paint them.
c)Bend brush works in a very annoying and unpredictable fashion and doesn't provide any control of direction .
Consider using the “Comb Fur” tool before using the “Paint Bend” tool. Hairs should bend in the combed direction. Note that both bend and comb values will have noise added to them make the fur look less regular. If the hairs are near perpendicular to the skin, the combed direction may be poorly defined (especially after noise is added). To reduce these noise values, look in the “Hairs > Guide > (Comb|Bend|Twist)” tabs.
Technical Discussion » modifydata dop driving sops
- derrick
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With Houdini 12.0.538, the Bullet Solver will update the position and velocity of the glue object. The difference in where impact data is recorded is still a problem.
Technical Discussion » LSystem and wires
- derrick
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The Wire Solver expects to work with polygons but the tube version of the tree contains mesh primitives. Consider using a Convert SOP to convert the mesh primitives into polygons.
Technical Discussion » HDK : GU_Fur
- derrick
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The Fur SOP interpolates the guide hairs but does not perform any kind of dynamics simulation. Any dynamics would have to be applied to the guide hairs before they are given to the Fur SOP.
The Fur SOP supports two ways of specifying guide hairs. One method requires the number of guide hairs to match the number of points in the skin geometry. The other method (the default when using the Fur Object) lets you place guide hairs at arbitrary positions on a character. The Fur SOP will use the second method if the guide hairs have a float3 primitive attribute called “guideorigin” indicating where the hair is attached on the character in its rest pose.
The Fur SOP supports two ways of specifying guide hairs. One method requires the number of guide hairs to match the number of points in the skin geometry. The other method (the default when using the Fur Object) lets you place guide hairs at arbitrary positions on a character. The Fur SOP will use the second method if the guide hairs have a float3 primitive attribute called “guideorigin” indicating where the hair is attached on the character in its rest pose.
Technical Discussion » HDK : GU_Fur
- derrick
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The Fur SOP is a thin wrapper around GU_Fur. It basically passes the input geometries and parameters directly to GU_Fur and implements hooks to capture any errors and warning messages produced. The GU_Fur instance used by the Fur SOP is a temporary object used when cooking and does not persist after cookMySop() finishes.
Technical Discussion » Question on converting curves for use as hair guides
- derrick
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jimc
However, as you can see things, don't quite work (see 1st attachment image). The black lines is the fur adjusted, the light grey is the templated guide curves. Anyone have any ideas what's wrong with this? I'm attached the hip file if that helps. It looks like there's something that's causing them to be flipped around? I'm sure there's something silly and obvious that I'm missing, I just don't know what yet.
For guide hairs, the first vertex represents the root and the last vertex represents the tip. Your geometry has these reversed. Applying a Reverse SOP on the guide hairs should fix the problem.
Technical Discussion » painting fur clumps
- derrick
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Arrev
I'm a bit confused on how the paint clumping tool works. My fur density is painted with average scalp coverage (for a human). With the fur clumping brush, I have painted a line down the middle of my head model (from forehead to the back of the head), with an opacity value of 1. Everywhere else is 0. I'm trying to create a “mohawk” of clump hairs.
For some reason when I turn on clumping, there are clump hairs all over where I painted density instead of just where I painted with the fur clumping tool. My impression was that the paint clump tool was to give the artist local control over where the clump hairs are. Am I doing something wrong? Or is it not possible to paint clump hairs in just a specific place?
The “Paint Clumping” tool lets you customize how much the clump hairs affect the shape of the fur. It does not affect where clump hairs are placed. The shape of hairs located in areas where you painted with a value of 1 will be fully affected by the clump hairs. The shape of hairs located in areas where you painted a value of 0 will not be affected by the clump hairs.
The “Paint Density” tool will let you control where hairs are placed. It will affect rendered hair, guide hairs, and clump hairs. If you want to place clump hairs independently of where fur will be located, consider first using the “Paint Density” tool then moving the two nodes it created (the Attrib Create SOP and the Paint SOP) to the clumps network (insert them between the clumps/merge_skin and clumps/create_clump_hairs nodes).
Technical Discussion » Wire solver attracting forces
- derrick
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sabotage3d
Hello guys I was wondering is there a way to control the wire object with custom forces in vopsop like SDF attraction. Like attracting curves to an goal object.
Custom forces can be specified by creating an attribute called “fexternal” on the Wire Object's “RestGeometry” subdata (described on the Wire Object DOP's help page). The force values could be updated at each time step using a SOP Solver. Attached is a simple working example.
Technical Discussion » capture layer paint: smoothing?
- derrick
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When painting, the left and middle mouse buttons are bound to operations. These bindings can be changed by right clicking in the viewport and selecting another operation.
Technical Discussion » Fur. Strange results of calculation "guideorigin"
- derrick
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