After watching the old masterclasses was able to do just such a flag.
He does not behave properly, but I can not figure out what was wrong.
It freezes and does not develop. very strange cloth.
I tried all the options, but nothing comes out
and I have not found any information about H and cloth in the network
documentation for information counter is very small, and the lesson “How to make a waving flag” is not working
Creating flag
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- hudmike
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- aweaklingchild
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- hudmike
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already tried, but that is not real cloth
I do not know why, but all forces acting on the fabric as the water and not as air. No twists of fabric and beautiful curves. fabric looks like a piece of cardboard
(same effect if move just origin of displacement)
nice example in maya:
http://www.youtube.com/watch?feature=player_detailpage&v=2iUX-I1Z-hM#t=418s [youtube.com]
in most app we have offset and evolution for noise, in h only offset?
I do not know why, but all forces acting on the fabric as the water and not as air. No twists of fabric and beautiful curves. fabric looks like a piece of cardboard
(same effect if move just origin of displacement)
nice example in maya:
http://www.youtube.com/watch?feature=player_detailpage&v=2iUX-I1Z-hM#t=418s [youtube.com]
in most app we have offset and evolution for noise, in h only offset?
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- hudmike
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- pelos
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- hudmike
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- old_school
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A few things.
Noise on wind. You set Roughness to 1 (default) but you set Turbulence to 0. This means no additional octaves of noise to give you nice turbulent effect. Set to 4 for the given resolution of the mesh and see if that helps.
Try anisotropic noise on the wind. Set Amplitude for X and Z say to 5 or 6 and leave Y on 3. Assumption is that the noise moving fast past the flag will have more strength in the XZ plane and less in the Y.
Go much higher with the Normal Drag on the Cloth Object DOP. Go even lower on the tangent drag.
These two parameters are what most likely will affect the flag behaviour the most. The tangent drag is the part of the cloth surface that is in alignment with the forces (wind) and in this case little drag will be applied.
The Normal Drag is the part of the cloth that is being hit by the wind. With a larger value, the drag will be higher and will cause that part of the cloth to have more damping.
Manipulate both. Generally Normal drag is much higher than Tangent Drag.
Try Normal Drag at 20 and Tangent Drag at 0.01.
Leave the shear at default 200 and then reduce the Weak Bend Stiffness to a much lower number, try even 0.05.
You could even further tweak the wind amplitude in CHOPs to get more wind bursts with lulls.
Noise on wind. You set Roughness to 1 (default) but you set Turbulence to 0. This means no additional octaves of noise to give you nice turbulent effect. Set to 4 for the given resolution of the mesh and see if that helps.
Try anisotropic noise on the wind. Set Amplitude for X and Z say to 5 or 6 and leave Y on 3. Assumption is that the noise moving fast past the flag will have more strength in the XZ plane and less in the Y.
Go much higher with the Normal Drag on the Cloth Object DOP. Go even lower on the tangent drag.
These two parameters are what most likely will affect the flag behaviour the most. The tangent drag is the part of the cloth surface that is in alignment with the forces (wind) and in this case little drag will be applied.
The Normal Drag is the part of the cloth that is being hit by the wind. With a larger value, the drag will be higher and will cause that part of the cloth to have more damping.
Manipulate both. Generally Normal drag is much higher than Tangent Drag.
Try Normal Drag at 20 and Tangent Drag at 0.01.
Leave the shear at default 200 and then reduce the Weak Bend Stiffness to a much lower number, try even 0.05.
You could even further tweak the wind amplitude in CHOPs to get more wind bursts with lulls.
There's at least one school like the old school!
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- hudmike
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Houdini flag looks like morph between some states.
look at nCloth simple example
http://www.youtube.com/watch?v=mjp1177u-Ic [youtube.com]
in example no any turbulence or noise on wind or on gravity
all curves/swirls on nCloth are the result of internal forces of of cloth themselves. wind = const
in H we have morphing cardboard (witn all that noises and other “magic”) and like something pin right top corner
look at nCloth simple example
http://www.youtube.com/watch?v=mjp1177u-Ic [youtube.com]
in example no any turbulence or noise on wind or on gravity
all curves/swirls on nCloth are the result of internal forces of of cloth themselves. wind = const
in H we have morphing cardboard (witn all that noises and other “magic”) and like something pin right top corner
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- anon_user_37409885
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- hudmike
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- old_school
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I removed all tweaks and settings and set parms to default.
It is better to use the vel direction right in the Cloth Object DOP. Wind DOP just doesn't work nearly as nicely as the vel direction on the Cloth Object.
Mass of Cloth has an effect so try making heavier or lighter to suit but I worked at it's default. This is a large flag at 1.5 meters in length. The only thing I changed was the thickness of the cloth to help with the penetration. Note that this will increase the mass as the volume (thickness) of the cloth is multiplied by the density.
Note that you can go to the Cloth Solver and change the Spatial Scale to make a larger or smaller scale. This scales all the internal properties of the cloth. It works pretty well. Allows you to change scale without changing anything else.
I set both stiffnesses to negligible values or 0. I set the shear down as well.
I set the Normal and Tangent Drag way to high in that previous file. Too much drag will make it seem stiffer as you noticed.
See the attached example file. Looks more organic now.
Looking at some real reference footage:
http://www.youtube.com/watch?v=KTfT2AFWJQQ [youtube.com]
and
http://www.youtube.com/watch?v=Lm_imE1a37Q [youtube.com]
That first sim, the flag does look stiff.
The second reference shows nice rippling from the top attachment point and again the flag looks a bit stiff in the wind.
After running the sim a few times, I can see that the leading edge of the cloth can change the sim as it flaps back and forth.
The ncloth sim doesn't get the nice waves draping from the top attachment point and rippling through, probably due to the two attachment points and the front leading edge gets caught up and doesn't flap back and forth to induce the ripples propagating down the flag.
I attached another Houdini scene that hopefully gets a better result. Byy adjusting the vel direction you get rippling and draping somewhat similar to the real flag reference. I put a noise() expression in there to vary the velocity force a wee bit.
It is better to use the vel direction right in the Cloth Object DOP. Wind DOP just doesn't work nearly as nicely as the vel direction on the Cloth Object.
Mass of Cloth has an effect so try making heavier or lighter to suit but I worked at it's default. This is a large flag at 1.5 meters in length. The only thing I changed was the thickness of the cloth to help with the penetration. Note that this will increase the mass as the volume (thickness) of the cloth is multiplied by the density.
Note that you can go to the Cloth Solver and change the Spatial Scale to make a larger or smaller scale. This scales all the internal properties of the cloth. It works pretty well. Allows you to change scale without changing anything else.
I set both stiffnesses to negligible values or 0. I set the shear down as well.
I set the Normal and Tangent Drag way to high in that previous file. Too much drag will make it seem stiffer as you noticed.
See the attached example file. Looks more organic now.
Looking at some real reference footage:
http://www.youtube.com/watch?v=KTfT2AFWJQQ [youtube.com]
and
http://www.youtube.com/watch?v=Lm_imE1a37Q [youtube.com]
That first sim, the flag does look stiff.
The second reference shows nice rippling from the top attachment point and again the flag looks a bit stiff in the wind.
After running the sim a few times, I can see that the leading edge of the cloth can change the sim as it flaps back and forth.
The ncloth sim doesn't get the nice waves draping from the top attachment point and rippling through, probably due to the two attachment points and the front leading edge gets caught up and doesn't flap back and forth to induce the ripples propagating down the flag.
I attached another Houdini scene that hopefully gets a better result. Byy adjusting the vel direction you get rippling and draping somewhat similar to the real flag reference. I put a noise() expression in there to vary the velocity force a wee bit.
There's at least one school like the old school!
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- hudmike
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- anon_user_37409885
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- TomMan
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This thread is about two years old. “unfortunately” I need to create a flag on my own. I just did the Maya tutorial and I love the results. Since I don't want to use Maya and stick with Houdini's procedural approach, how can this be done?
I looked at the examples here, but can't say that I'm impressed. I played for about 3-4h with the cloth solver in H. It's simply a pain and looks horrible.
Some guys add odforum gave me some tips to use grain sheets, but now my flag just bounces like a piece of rubber, even worse than before. O.k.; I'm new to H, but well used to use ICE. So I guess there seems to be some mystery.
I attached both my scenes. But getting close to the Maya example, impossible. Maya simulates with around 8fps, H with 0.5-1.0fps. That's painful. Can't believe that this is still tricky to do, since the results look like the one's I got from Lightwave a decade before.
Any help is welcome!
Cheers
Tom
I looked at the examples here, but can't say that I'm impressed. I played for about 3-4h with the cloth solver in H. It's simply a pain and looks horrible.
Some guys add odforum gave me some tips to use grain sheets, but now my flag just bounces like a piece of rubber, even worse than before. O.k.; I'm new to H, but well used to use ICE. So I guess there seems to be some mystery.
I attached both my scenes. But getting close to the Maya example, impossible. Maya simulates with around 8fps, H with 0.5-1.0fps. That's painful. Can't believe that this is still tricky to do, since the results look like the one's I got from Lightwave a decade before.
Any help is welcome!
Cheers
Tom
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- old_school
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Use Cloth Solver for Cloth imho in H14.
If you wanted to try an alternate solver, it would be the wire solver which is a point-edge solver similar to nCloth. The wire solver can solve against poly surfaces as easily as it does for wires.
Using Grains for cloth is fine but I'd resort to that if I was combining this with other grain objects. For example using cloth like attributes for a top layer of Sod with a second layer about 0.2 units thick for roots then under that 1 to 2 metres of clay mud like stuff for flying crap in to ground.
Sticking to the Cloth FEM Solver, just get your flag to drop nicely first. Bypass the Wind Force.
See the example file I worked up on top of yours. I backed off a whole bunch of stuff then worked it up bit by bit. I put the notes in the file. It's getting better but I still would like to add much more “character” movement to the flag.
Some interesting facts about the FEM Cloth Solver:
- The polygon cloth is used to store the results of the cloth solve between DOP sub-steps (not to be confused with the Cloth FEM Solver sub-steps).
- The Cloth solver is solving on the surface, not using the points or edges of the input geometry. This is very different from our wire solver and nCloth which carry forces on the points of the geometry.
Solving surfaces should give you more predictable results on larger or smaller cloth. It is also what allows the Spatial Scale parameter to work pretty well.
This trait also makes the FEM Cloth Solver much less tolerant to topology changes. For example, doubling the resolution should get you the same bulk motion but with much more detail.
- You can apply your own force direction for uvw through the use of a special uv attribute on the cloth. Discontinuous uvw attributes will solve as discrete patches on the cloth. This allows you to mock seams on flags for example. This will then encourage topology to follow cloth features and not follow standard modelling practices. You can encourage force lines through your cloth using these techniques.
If you wanted to try an alternate solver, it would be the wire solver which is a point-edge solver similar to nCloth. The wire solver can solve against poly surfaces as easily as it does for wires.
Using Grains for cloth is fine but I'd resort to that if I was combining this with other grain objects. For example using cloth like attributes for a top layer of Sod with a second layer about 0.2 units thick for roots then under that 1 to 2 metres of clay mud like stuff for flying crap in to ground.
Sticking to the Cloth FEM Solver, just get your flag to drop nicely first. Bypass the Wind Force.
See the example file I worked up on top of yours. I backed off a whole bunch of stuff then worked it up bit by bit. I put the notes in the file. It's getting better but I still would like to add much more “character” movement to the flag.
Some interesting facts about the FEM Cloth Solver:
- The polygon cloth is used to store the results of the cloth solve between DOP sub-steps (not to be confused with the Cloth FEM Solver sub-steps).
- The Cloth solver is solving on the surface, not using the points or edges of the input geometry. This is very different from our wire solver and nCloth which carry forces on the points of the geometry.
Solving surfaces should give you more predictable results on larger or smaller cloth. It is also what allows the Spatial Scale parameter to work pretty well.
This trait also makes the FEM Cloth Solver much less tolerant to topology changes. For example, doubling the resolution should get you the same bulk motion but with much more detail.
- You can apply your own force direction for uvw through the use of a special uv attribute on the cloth. Discontinuous uvw attributes will solve as discrete patches on the cloth. This allows you to mock seams on flags for example. This will then encourage topology to follow cloth features and not follow standard modelling practices. You can encourage force lines through your cloth using these techniques.
There's at least one school like the old school!
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- Dmitry Gorohov
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hi community, some times ago i've got a pretty simple task - make a waving flag, you know,cloth object, solver, wind force. Buuut, in h15 cloth become a little strange. Wind force do some strange stuff with fem cloth, btw in tutorial “waving flag” http://www.sidefx.com/docs/houdini15.0/cloth/flagin [sidefx.com] help suggests to use wind force but in here http://www.sidefx.com/docs/houdini15.0/cloth/influencing_cloth [sidefx.com] sfx told :“You should not use the Wind Force DOP or any of the other forces in DOPs because they will generate inferior results compared with the Air Drag model.”. Okay, buut when i tryed to use External Velocity Field it didnt work, after that i found this: http://forums.odforce.net/topic/24155-forces-in-dops/ [forums.odforce.net] and http://forums.odforce.net/topic/17556-cloth-arbitrary-vel-field/. [forums.odforce.net] So external velocity doesn't work too, according that, i have not any working wind force? Or i had missed something?
In a second way i need an advice about this https://www.youtube.com/watch?v=11GUii0MKvM [youtube.com] i've got alot of troubles with flags locating at the top of the mast . How to make close enough simulations? In this tread i found a lot of old good setups but, they dose not work in houdini 15, or i do something wrong? Thanks for help
In a second way i need an advice about this https://www.youtube.com/watch?v=11GUii0MKvM [youtube.com] i've got alot of troubles with flags locating at the top of the mast . How to make close enough simulations? In this tread i found a lot of old good setups but, they dose not work in houdini 15, or i do something wrong? Thanks for help
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- notawhale
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