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Houdini Indie and Apprentice » Setting Particles Up Vector (or always facing positive Z)
- rjq
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Houdini Indie and Apprentice » Setting Particles Up Vector (or always facing positive Z)
- rjq
- 12 posts
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I tried everything you said except for creating an “orient” attribute. It would be nice to control each particle in such a way, but at this time your solution is exactly what I needed.
Now the only thing I need to work on is having the particles furthest away accelerate faster than the ones closer to the emitter. I tried multiplying the Speed Scale in the Force node by $LIFE, but that didn't work too well. Everything still had a constant speed. Do I need to multiply by $PT as well?
Now the only thing I need to work on is having the particles furthest away accelerate faster than the ones closer to the emitter. I tried multiplying the Speed Scale in the Force node by $LIFE, but that didn't work too well. Everything still had a constant speed. Do I need to multiply by $PT as well?
Houdini Indie and Apprentice » Setting Particles Up Vector (or always facing positive Z)
- rjq
- 12 posts
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Houdini Indie and Apprentice » Setting Particles Up Vector (or always facing positive Z)
- rjq
- 12 posts
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I have a polygonal mesh box emitting particles from the center with no velocity or variance set to the particles, thus leaving a trail. After a certain frame a activate a follow force to have the particles go back to the center of the box as if it is being absorbed.
The issue that I am having is when the particles start moving towards the leader, they orient themselves toward the leader (to create an absorbing effect). I want them to keep their initial orientation (pointing toward the positive Z axis like when they are first emitted). I can't use a Trail SOP because I need a delay from when they are absorbed.
I have attached my HIP file so you can see what I am doing. Any advice or pointing out of my errors would be much appreciated.
The issue that I am having is when the particles start moving towards the leader, they orient themselves toward the leader (to create an absorbing effect). I want them to keep their initial orientation (pointing toward the positive Z axis like when they are first emitted). I can't use a Trail SOP because I need a delay from when they are absorbed.
I have attached my HIP file so you can see what I am doing. Any advice or pointing out of my errors would be much appreciated.
Houdini Lounge » Blood Splatter Issues
- rjq
- 12 posts
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Hi all,
I am trying to get an effect of blood splattering and sticking to a wall and have not been successful. I remember accomplishing the effect a few weeks ago but I can't find the HIP file.
Attached is the most recent HIP that I have been using. I am using particle liquids in a basic DOP and tried to add a collision node to my POP network to make the particles stick, but it has been to no avail. As usual, any help would be much obliged.
Best,
Ryan
I am trying to get an effect of blood splattering and sticking to a wall and have not been successful. I remember accomplishing the effect a few weeks ago but I can't find the HIP file.
Attached is the most recent HIP that I have been using. I am using particle liquids in a basic DOP and tried to add a collision node to my POP network to make the particles stick, but it has been to no avail. As usual, any help would be much obliged.
Best,
Ryan
Work in Progress » Rail Gun Bullet Trail Issues – Matching the film Eraser
- rjq
- 12 posts
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Hey all,
I am trying to make bullet trails that match the look of the trails made by the rail gun in the movie Eraser (here is a clip for reference: Eraser Rail Gun [youtube.com])
What it looks like to me is that they have a volume that has the solid property of metaballs, but then dissipates with a very high viscosity to cause the swirling. I have tried to convert metaballs to a fog volume and then use that as the density is a volume emitter, but still can't get the look right.
I think the key thing I am having issues with is the shader, getting that ramped look like a normal falloff with geometry, but I can't really figure out how to do it with volumes. I don't even know if that would be the way to solve it, that seems like just one piece. This way they dissipate seems to be an issue as well, I tried the dissipate microsolver, but couldn't get it to work. Attached is a version of a hip file I was using.
Any help/suggestions would be greatly appreciated.
I am trying to make bullet trails that match the look of the trails made by the rail gun in the movie Eraser (here is a clip for reference: Eraser Rail Gun [youtube.com])
What it looks like to me is that they have a volume that has the solid property of metaballs, but then dissipates with a very high viscosity to cause the swirling. I have tried to convert metaballs to a fog volume and then use that as the density is a volume emitter, but still can't get the look right.
I think the key thing I am having issues with is the shader, getting that ramped look like a normal falloff with geometry, but I can't really figure out how to do it with volumes. I don't even know if that would be the way to solve it, that seems like just one piece. This way they dissipate seems to be an issue as well, I tried the dissipate microsolver, but couldn't get it to work. Attached is a version of a hip file I was using.
Any help/suggestions would be greatly appreciated.
Technical Discussion » Multi-take rendering to a single EXR
- rjq
- 12 posts
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There is a way to render out a shadow pass as a separate take, but that would put it as another channel along with all of the other image planes in a single Open EXR file. The advice that Circus Monkey gave worked, and I also found a way by reconstructing the shadow shader within whatever shader I was using and adding that export parameter to an image plane in my Mantra node.
Technical Discussion » Multi-take rendering to a single EXR
- rjq
- 12 posts
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I see what you did with the Switcher Node, but I am not sure how the $RENDERPASS is passed on (no pun intended) to the Image Plane parameter in a ROP so I can get the shadow pass along with the other Image Planes in a single EXR.
I basically don't know what to type in for the VEX variable in the Mantra node. Thank you for being so helpful with this.
I basically don't know what to type in for the VEX variable in the Mantra node. Thank you for being so helpful with this.
Technical Discussion » Multi-take rendering to a single EXR
- rjq
- 12 posts
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Looking into it more, I notice that the shadow matte shader needs to be plugged into its own Output Variables and Parameters node within the Vex Surface SHOP. Does that mean that you can't do the same thing with a shadow as done with the Object ID and Ambient Occlusion because it the color, transparency, and face forward all need to be output from the VEX Builder as one group?
Technical Discussion » Multi-take rendering to a single EXR
- rjq
- 12 posts
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Thank you so much. I went through it a few times and it seems to make sense. I had never made my own shader in Houdini (I used to make procedural shaders in Maya all the time), but it seems to be a bit easier than I thought.
Best,
RJQ
Best,
RJQ
Technical Discussion » Multi-take rendering to a single EXR
- rjq
- 12 posts
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I understand the basis behind how that would work, I think it would help if I saw the implementation. I would love to see that file as an example, so I can see the way you set it up. Thanks for the help and I hope the show went well.
RJQ
RJQ
Technical Discussion » Multi-take rendering to a single EXR
- rjq
- 12 posts
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I know how to add image planes onto a Montra render that grabs the export from shaders applied to the various geometry in the scene. Is there a way to have different shaders for the same object going into the same OpenEXR file?
For example, if I have a shadow pass and an ambient occlusion pass as two separate takes, can I have those to takes render out as two separate channels to an OpenEXR at render time?
For example, if I have a shadow pass and an ambient occlusion pass as two separate takes, can I have those to takes render out as two separate channels to an OpenEXR at render time?
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