DForce Explosions

WSC

How do you get someone to sit in a dforce dress without massive explosion of the garment? I don't get the point of dforce if the only value is having the person standing in a field, by themselves, with their arms held out.... and no other character even looking at them.

TheMysteryIsThePoint

The problem is probably intersections in mesh between the character and the prop.

If you are willing to learn a little Blender, you can easily solve this. What you do is to:

1. Export both the character and prop to Blender as obj, at the frame where the character is sitting. It'll come in with the wrong transform, but that's OK, we're going to send it back to DS.
2. Apply a boolean modifier to the prop, using the character as the other shape.
3. Select difference.
4. Apply the modifier. You've not got your charcter's shape cut out of the prop.
5. They will have been mangled by the modifier, so reset the prop's normals.
6. Delete the character.
7. Export the prop back to DS.
8. Hide the original prop, and simulate against your modified prop. It'll provide "just enough" leeway for the sim not to explode.
9. If by some chance it still explodes, export the modified prop back to Blender, and in edit mode, select the faces around where there's contact with the character and use Alt-S to shrink the prop just a wee bit along it's normals in those affected areas and export back to DS again.

Blender is an incredibly useful tool for fixing an untold number of things and it is worth it to become at least semi-proficient in it, even if you have no further interest in Blender itself.

 

Richard Haseltine

You can also try adjusting the pose to make sure that the figure doesn't intersect with anything as it goes from (I assume) the memorised, probably zero, pose to the sitting pose. What you need to avoid is trapping the object(s) being simulated.

Other than that, dForce simualtion works by assessing "energy" (from movement, wind, and gravity) in the cloth and, through successive iterations, adjusting the mesh to minimise it. If the pose is changing too fast or the simualted object too constrained (but not outright trapped), or if the simulated object iss et to be heavy or stiff, energy can build up more quickly than the algorithm can diffuse it - in that case too an explosion results. Adjusting the iterations per frame and subframes in Simulation Settings can help with that by allowing more steps to diffuse the energy before the next change.

WSC

TheMysteryIsThePoint said:

The problem is probably intersections in mesh between the character and the prop.

If you are willing to learn a little Blender, you can easily solve this. What you do is to:

1. Export both the character and prop to Blender as obj, at the frame where the character is sitting. It'll come in with the wrong transform, but that's OK, we're going to send it back to DS.
2. Apply a boolean modifier to the prop, using the character as the other shape.
3. Select difference.
4. Apply the modifier. You've not got your charcter's shape cut out of the prop.
5. They will have been mangled by the modifier, so reset the prop's normals.
6. Delete the character.
7. Export the prop back to DS.
8. Hide the original prop, and simulate against your modified prop. It'll provide "just enough" leeway for the sim not to explode.
9. If by some chance it still explodes, export the modified prop back to Blender, and in edit mode, select the faces around where there's contact with the character and use Alt-S to shrink the prop just a wee bit along it's normals in those affected areas and export back to DS again.

Blender is an incredibly useful tool for fixing an untold number of things and it is worth it to become at least semi-proficient in it, even if you have no further interest in Blender itself.

Thanks. Interesting, but certainly beyond what I'm capable of for now. You're right though, going to need to improve my skills in other tools.

WSC

Richard Haseltine said:

You can also try adjusting the pose to make sure that the figure doesn't intersect with anything as it goes from (I assume) the memorised, probably zero, pose to the sitting pose. What you need to avoid is trapping the object(s) being simulated.

Other than that, dForce simualtion works by assessing "energy" (from movement, wind, and gravity) in the cloth and, through successive iterations, adjusting the mesh to minimise it. If the pose is changing too fast or the simualted object too constrained (but not outright trapped), or if the simulated object iss et to be heavy or stiff, energy can build up more quickly than the algorithm can diffuse it - in that case too an explosion results. Adjusting the iterations per frame and subframes in Simulation Settings can help with that by allowing more steps to diffuse the energy before the next change.

Thanks. That's what's frustrating. It doesn't untill it comes into contact with the seat. The model is not even touching the seat, but it has to come into some contact at the end....

Padone

It may be confusing since those tools are supposed to be "physics simulations". But the truth is they can't do real physics, so you have to use tricks. As others said avoid "trapping" the cloth, so in your example the figure just can't sit for real, you have to leave some space between the figure and the chair. You may also use an invisible proxy for collisions instead of the chair, that will be easier to compute for the cloth engine.

This is the same in any cloth simulator, not just dforce.

marble

Also, I often forget to make sure that the cloth doesn't pass through some other object as the pose is transforming from "memorized" to your seated pose. Sometimes you have to start the pose from up above the chair somehow - which is not easy because the Right-Click - Parameters>Memorize>Memorize Figure Pose doesn't work with the dForce "Start from Memorized Pose" option. So the only other option that I know of is to use the animation timeline.

WSC

Padone said:

It may be confusing since those tools are supposed to be "physics simulations". But the truth is they can't do real physics, so you have to use tricks. As others said avoid "trapping" the cloth, so in your example the figure just can't sit for real, you have to leave some space between the figure and the chair. You may also use an invisible proxy for collisions instead of the chair, that will be easier to compute for the cloth engine.

This is the same in any cloth simulator, not just dforce.

Yes, there's room between the character and the chair, but still breaking. I'll have to tinker with it. Some garments see to have less problems than others....

WSC

marble said:

Also, I often forget to make sure that the cloth doesn't pass through some other object as the pose is transforming from "memorized" to your seated pose. Sometimes you have to start the pose from up above the chair somehow - which is not easy because the Right-Click - Parameters>Memorize>Memorize Figure Pose doesn't work with the dForce "Start from Memorized Pose" option. So the only other option that I know of is to use the animation timeline.

Character is coming down from above. How can the animation timeline help?

WendyLuvsCatz

I can only do them animated moving the chair into place

WSC

I think I see what's going on. I have parts of the figure's limbs overlapping and the clothing is in between the two....

Richard Haseltine

WSC said:

marble said:

Also, I often forget to make sure that the cloth doesn't pass through some other object as the pose is transforming from "memorized" to your seated pose. Sometimes you have to start the pose from up above the chair somehow - which is not easy because the Right-Click - Parameters>Memorize>Memorize Figure Pose doesn't work with the dForce "Start from Memorized Pose" option. So the only other option that I know of is to use the animation timeline.

Character is coming down from above. How can the animation timeline help?

Going from memorised pose to final pose the system just advances everything uniformly, if you use the Timeline to run a playrange simulation you can set staging points to avoid issues like self-intersection.

TBorNot

You can get a stick and one flag from the demonstration example to explode too.  Delete all the balls and all but one stick and flag.  Turn off "Start from memorized pose" and kablooey!  Even when it does work, poke thrus of clothing are rampant, so I pretty much gave up on the whole thing.

 

 

WSC

Richard Haseltine said:

WSC said:

marble said:

Also, I often forget to make sure that the cloth doesn't pass through some other object as the pose is transforming from "memorized" to your seated pose. Sometimes you have to start the pose from up above the chair somehow - which is not easy because the Right-Click - Parameters>Memorize>Memorize Figure Pose doesn't work with the dForce "Start from Memorized Pose" option. So the only other option that I know of is to use the animation timeline.

Character is coming down from above. How can the animation timeline help?

Going from memorised pose to final pose the system just advances everything uniformly, if you use the Timeline to run a playrange simulation you can set staging points to avoid issues like self-intersection.

Bottomline, I just need to learn what the heck I'm doing....

WSC

TBorNot said:

You can get a stick and one flag from the demonstration example to explode too.  Delete all the balls and all but one stick and flag.  Turn off "Start from memorized pose" and kablooey!  Even when it does work, poke thrus of clothing are rampant, so I pretty much gave up on the whole thing.

 

Maybe it's just me, but I feel like last versions were more "forgiving".

Peter_DA

On youtube I saw a video that explains this problem really well (my opinion). The video is from esha

WSC

Peter_DA said:

On youtube I saw a video that explains this problem really well (my opinion). The video is from esha

Excellent. Thanks.