Hi, just stumbled on this as well. Old thread but can be good to write anyways.
Just make sure that the attribute "pscale" exists on the points of the incoming curve. You do not need to enter anything in the width parameter of the sweep node. I guess pscale works as a multiplier of the width parm value.
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Houdini Indie and Apprentice » Using attribute to drive parameters
- Petfactory
- 16 posts
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Houdini for Realtime » VDB to Unreal HeterogeneousVolume placement
- Petfactory
- 16 posts
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Hi!
In Houdini I have simulated and exported a VDB sequence that I am importing into Unreal as an animated SVT.
I am having some issues with aligning the Heterogeneous Volume actor so that it matches the transform in Houdini.
What I have done so far to get the placement of a Static SVT to align is the following:
Location x = Houdini center x * 100 (The center of the Houdini sim)
Location y = Houdini center z * 100
Location z = Houdini center y * 100
rotation x = 90
rotation Y = 0
rotation Z = 0
scale x = 100 * Houdini sim division size (if the sim div size is 0.01 that would be a scale of 1.0)
scale Y = - 100 * Houdini sim division size
scale Z = 100 * Houdini sim division size
If the SVT is animating I can not get the Location to align. I have tried using the first frame center, the last frame center, the "combined center" of all frames of the sim... but I have not been able to align it yet.
Does any one know the correct way to align an animated SVT in UE?
Thanks!
In Houdini I have simulated and exported a VDB sequence that I am importing into Unreal as an animated SVT.
I am having some issues with aligning the Heterogeneous Volume actor so that it matches the transform in Houdini.
What I have done so far to get the placement of a Static SVT to align is the following:
Location x = Houdini center x * 100 (The center of the Houdini sim)
Location y = Houdini center z * 100
Location z = Houdini center y * 100
rotation x = 90
rotation Y = 0
rotation Z = 0
scale x = 100 * Houdini sim division size (if the sim div size is 0.01 that would be a scale of 1.0)
scale Y = - 100 * Houdini sim division size
scale Z = 100 * Houdini sim division size
If the SVT is animating I can not get the Location to align. I have tried using the first frame center, the last frame center, the "combined center" of all frames of the sim... but I have not been able to align it yet.
Does any one know the correct way to align an animated SVT in UE?
Thanks!
Technical Discussion » RBD bullet solver cone twist constraint
- Petfactory
- 16 posts
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Thank you for your quick reply!
Really interesting to hear about the improvements in H20.
Regards, Johan
Really interesting to hear about the improvements in H20.
Regards, Johan
Technical Discussion » RBD bullet solver cone twist constraint
- Petfactory
- 16 posts
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npetit
Here's a quick example showing how you might setup some conetwist constraints to use with the RBD Bullet Solver SOP.
Notice I'm only driving a few of the conetwist constraint properties via attributes on the constraint prims.
If you want different settings per constraint for other properties, you'll need to add them as attributes and make sure their default values (which will be multiplied by the prim attributes) on the RBD Bullet Solver are set to 1.
The tricky thing with the conetwist constraint would have to be the motor_target. It's not very intuitive in the slightest. While the parameter on both the RBD Bullet Solver SOP and the ConeTwist ConRel DOP specify a motor_targetr vector param, you need to set a quaternion motor_target attribute. This attribute needs to be updated at every timestep, so make sure you add it to the list of constraint attributes to be updated by the RBD Bullet Solver.
Hi, Thank you for your example file. In the file I noticed the same issue that I had when using a motor_target, that the motion is a bit "twitchy" it does not follow the same smooth rotation that the "driving" motor_target has. You might see in the gif that the visualized motor_target attr has a smooth rotation but the simulated object occasionally slows downs, and speeds up again.
Is there a way to use a motor_target and get a smooth motion?
The reason I want to use a motor_target on the cone twist constraint is do "drive" the wheels of a vehicle. Is there another "preferred" way of doing this. I have tried using v@w on the wheel objects but had some issues with "balancing" the force of the angular velocity.
Does anyone have some tips on how to drive the rotation of an rbd object in a stable and controllable way?
Regards, Johan
Edited by Petfactory - Sept. 4, 2023 04:08:26
Technical Discussion » Chop lag orient flip
- Petfactory
- 16 posts
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Thanks, so then if I would like to get an orient attrib I guess I could lag N and up and then "rebuild" the orient attrib?
The result from lagging N and up is not the same as when I lag orient but maybe this is to be expected. I attached a simple setup, any feedback/tips/ideas on how to improve are always welcome!
Thanks again
/ J
The result from lagging N and up is not the same as when I lag orient but maybe this is to be expected. I attached a simple setup, any feedback/tips/ideas on how to improve are always welcome!
Thanks again
/ J
Technical Discussion » Chop lag orient flip
- Petfactory
- 16 posts
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Hi!
I want to lag an orient attribute in chops but when I use lag I get this flipping seen in the gif. What would be the best way to get rid of this flipping?
I have attached a simple test setup.
Regards,
Johan
I want to lag an orient attribute in chops but when I use lag I get this flipping seen in the gif. What would be the best way to get rid of this flipping?
I have attached a simple test setup.
Regards,
Johan
Edited by Petfactory - Jan. 30, 2023 09:48:21
Solaris and Karma » Camera ray to tangent space
- Petfactory
- 16 posts
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Hi, I am trying to transform the camera ray to tangent space.
I am using a kma_rayimport node (Vector3, ray:direction)and a mtlxtransformvector to transform the vector. I could not find any documentation on which names to use in the fromspace, tospace parameters (I have tried space:world, space:tangent and other combinations but just guessing here)
Can anyone shed some light here
Best Regards,
Johan
I am using a kma_rayimport node (Vector3, ray:direction)and a mtlxtransformvector to transform the vector. I could not find any documentation on which names to use in the fromspace, tospace parameters (I have tried space:world, space:tangent and other combinations but just guessing here)
Can anyone shed some light here
Best Regards,
Johan
Houdini Engine for Unreal » Interior mapping on HDA
- Petfactory
- 16 posts
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Hi dpernuit,
Thanks for the info, refine Houdini proxy meshes works perfect.
Out of curiosity, do you know why it is needed to set the tangentu and tangentv vertex attr to {0,0,0} to get the interior mapping to work?
Thanks for the info, refine Houdini proxy meshes works perfect.
Out of curiosity, do you know why it is needed to set the tangentu and tangentv vertex attr to {0,0,0} to get the interior mapping to work?
Houdini Engine for Unreal » Interior mapping on HDA
- Petfactory
- 16 posts
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Thanks Melt!
Following your advice made it work after I bake the HDA. Baking it makes both the baked result and the HDA work with the interior mapping.
Before it is baked (or if a parameter of the HDA is changed) it only shows the "x-axis". I have attached a gif showing the HDAin unreal. Does anyone know why it behaves like this?
Thanks,
/ Johan
Following your advice made it work after I bake the HDA. Baking it makes both the baked result and the HDA work with the interior mapping.
Before it is baked (or if a parameter of the HDA is changed) it only shows the "x-axis". I have attached a gif showing the HDAin unreal. Does anyone know why it behaves like this?
Thanks,
/ Johan
Houdini Engine for Unreal » Interior mapping on HDA
- Petfactory
- 16 posts
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Hi,
I am creating an HDA (Houdini Indie 19.0.652) to be used in Unreal 5.02.
When I add a material to the HDA it looks as expected but when I try an interior mapping shader ("the built in") there is a problem.
I have attached a gif showing the issue.
The first plane from the left is a standard plane (unreal primitive) and it behaves as expected.
The second plane is an fbx exported from Houdini, but generated from the same HDA that I am using in Unreal, it also looks fine.
The third is the HDA and the fourth is the baked HDA. As you can see it looks strange.
Have any one got any ideas how to fix this? It would be nice to be able to use the HDA directly in engine, without having to export an fbx.
Regards,
Johan
I am creating an HDA (Houdini Indie 19.0.652) to be used in Unreal 5.02.
When I add a material to the HDA it looks as expected but when I try an interior mapping shader ("the built in") there is a problem.
I have attached a gif showing the issue.
The first plane from the left is a standard plane (unreal primitive) and it behaves as expected.
The second plane is an fbx exported from Houdini, but generated from the same HDA that I am using in Unreal, it also looks fine.
The third is the HDA and the fourth is the baked HDA. As you can see it looks strange.
Have any one got any ideas how to fix this? It would be nice to be able to use the HDA directly in engine, without having to export an fbx.
Regards,
Johan
Technical Discussion » Karma: materialX Constant unshaded surface: how to
- Petfactory
- 16 posts
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Technical Discussion » Karma: materialX Constant unshaded surface: how to
- Petfactory
- 16 posts
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Hi,
Thank you for your quick answer.
It works perfect. In the render geo settings, I set the shading > render visibility to "visible only to primary rays" to also avoid having the geo cast shadows.
It seems like the mtlxuniform_edf only works in the cpu engine. It would be really nice to be able to use a "constant unshaded surface" in the gpu engine, do you know if that is possible?
Thank you for your quick answer.
It works perfect. In the render geo settings, I set the shading > render visibility to "visible only to primary rays" to also avoid having the geo cast shadows.
It seems like the mtlxuniform_edf only works in the cpu engine. It would be really nice to be able to use a "constant unshaded surface" in the gpu engine, do you know if that is possible?
Technical Discussion » Karma: materialX Constant unshaded surface: how to
- Petfactory
- 16 posts
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jsmack
Use the MtlX Uniform EDF to create a constant (unshaded) shader.
https://www.sidefx.com/docs/houdini/nodes/vop/mtlxuniform_edf.html [www.sidefx.com]
There is no turning off 'emission illuminates objects', for that set the bounces to 0.
Hi,
I am quite new to Lops, how do I set the bounces to 0?
Regards,
Johan
Technical Discussion » python Multi-line String
- Petfactory
- 16 posts
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Thank you for this. It pointed me in the right direction.
If you want a multiline string param to use Python:
If you want to inspect a node the asCode function is really nice.
To write it to a file we can execute snippet below in the python shell
If you want a multiline string param to use Python:
...setTags({"editor": "1", "editorlang": "python"})
If you want to inspect a node the asCode function is really nice.
To write it to a file we can execute snippet below in the python shell
with open('/path/to/somewhere/as_code.py', 'w') as f: f.write(hou.node('obj/geo1/your_node').asCode())
SI Users » Stylesheet: background-color of QWidget
- Petfactory
- 16 posts
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I had a look in the qt docs (which I should have done in the first place)
The dot-selector matches instances of the class, but not of its subclasses
Qt Stylesheet syntax [doc.qt.io]
The dot-selector matches instances of the class, but not of its subclasses
Qt Stylesheet syntax [doc.qt.io]
Edited by Petfactory - March 13, 2018 14:05:50
SI Users » Stylesheet: background-color of QWidget
- Petfactory
- 16 posts
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Hi,
I noticed that the background-color af a QWidget is not the grey color that I would expect (rgb(58, 58, 58))
I had a look in the stylesheet and the QWidget is prepended with a dot.
If this dot is removed the background gets the grey color. I am probably missing something but what is the purpose of the dot?
Best Regards,
Johan
I noticed that the background-color af a QWidget is not the grey color that I would expect (rgb(58, 58, 58))
I had a look in the stylesheet and the QWidget is prepended with a dot.
.QWidget
{
background-color: rgb(58, 58, 58);
}
If this dot is removed the background gets the grey color. I am probably missing something but what is the purpose of the dot?
Best Regards,
Johan
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