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dForce cloth not colliding

IsaacNewtonIsaacNewton Posts: 1,300
in Daz Studio Discussion

I have noticed that when I apply a dForce dynamic modifier to a clothing item not made for the figure (eg a V4 dress on a G8f figure), sometimes as the figure shifts pose the clothing does not collide with the figure and move, but simply passes through the figure. Is there any way to stop this?

Comments

  • Richard HaseltineRichard Haseltine Posts: 102,436

    Do you have a geoGraft, such as the Anatomical Elelemts, applied? Or have you hidden areas with the Geometry Editor tool? These can cause collision to fail - the bug is fixed in a forthcomng build.

  • AndySAndyS Posts: 1,438

    As far as I observed, dForce generally turns the mesh's collision handling off. Instead it uses an own method, which also can be switched off or on in the simulation settings.
    But I think, if dForce would be able to accept and respect the existing collision handling of the mesh, many users would be happy not to search for special workarounds to avoid intersections.

  • Richard HaseltineRichard Haseltine Posts: 102,436

    dForce turns a Smoothing Modifier off, if present, and then back on again after completing the simulation. Is that what you mean? I don'tknow if there are other reasons not to run them in prallel but there'd be a hefty speed penalty if the Smoothing Modifier had to recaclculate after each simulation step (at least).

  • Daywalker DesignsDaywalker Designs Posts: 3,586
    Richard Haseltine said:

    dForce turns a Smoothing Modifier off, if present, and then back on again after completing the simulation. Is that what you mean? I don'tknow if there are other reasons not to run them in prallel but there'd be a hefty speed penalty if the Smoothing Modifier had to recaclculate after each simulation step (at least).

    I'm pretty sure he's talking about autofit collision or conforming.

  • ChoholeChohole Posts: 33,604

    AutoFit does not perform "collision," it performs "projection." Not the same thing.

  • IsaacNewtonIsaacNewton Posts: 1,300
    Daywalker Designs said:
    Richard Haseltine said:

    dForce turns a Smoothing Modifier off, if present, and then back on again after completing the simulation. Is that what you mean? I don'tknow if there are other reasons not to run them in prallel but there'd be a hefty speed penalty if the Smoothing Modifier had to recaclculate after each simulation step (at least).

    I'm pretty sure he's talking about autofit collision or conforming.

    No, I'm not talking about autofit collision... what Chohole says wink

    In a scene with one g8f figure which has a g8 /dForce compatible clothing item conformed to it and adjusted so that no part of the clothing is intersecting the figure (as far as i can tell), I pose the figure at say frame 15 (simple standing pose), change the Simulation settings to use the timeline frames then, switch the self collision option in Surfaces to OFF, then press Simulate. The figure starts to adopt the pose, the clothing trys to follow but not successfully. Parts of the clothing pass through parts of the figure. My understanding is that Collision should prevent any part of the clothing from passing through the figure, but it certainly does.

  • Richard HaseltineRichard Haseltine Posts: 102,436

    Have you tried increasing the subframes or the iterations per subframe in Simulation Settings? It may be that the cloth simply can't keep up with the figure if the figure is moving quickly. If it's not an animation, just an aniamted drape to get to a still  result, you cold also try usign more frames. I don't know if that will help but it sounds like a possible factor.

    Apparently the collision actually needs to be off, it isn't just a good idea off to preserve speed, because the changes made by the Smoothing Modifier Collision would confuse the dynamic simulation - adding extra movment (from smoothing) to the the speed and direction of movement used by the simulation, which would corrupt the process.

  • IsaacNewtonIsaacNewton Posts: 1,300
    Richard Haseltine said:

    Have you tried increasing the subframes or the iterations per subframe in Simulation Settings? It may be that the cloth simply can't keep up with the figure if the figure is moving quickly. If it's not an animation, just an aniamted drape to get to a still  result, you cold also try usign more frames. I don't know if that will help but it sounds like a possible factor.

    I repeated a simple draping simulation over 200 frames and it was a bit better but still the clothing intersected the figure. I would have thought that the draping process could include a step for each frame to move any polygons which intersect the collision object (eg the figure) outside the figure. Perhaps this would need to be followed by a smoothing process for the polys around the intersecting polys to avoid ugliness. 

    "Apparently the collision actually needs to be off, it isn't just a good idea off to preserve speed, because the changes made by the Smoothing Modifier Collision would confuse the dynamic simulation - adding extra movment (from smoothing) to the the speed and direction of movement used by the simulation, which would corrupt the process."

    Not sure what you are saying here. However, I thought that dForce switched off the Smoothing Modifer during the simulation process.

  • Richard HaseltineRichard Haseltine Posts: 102,436
    IsaacNewton said:
    Richard Haseltine said:

    Have you tried increasing the subframes or the iterations per subframe in Simulation Settings? It may be that the cloth simply can't keep up with the figure if the figure is moving quickly. If it's not an animation, just an aniamted drape to get to a still  result, you cold also try usign more frames. I don't know if that will help but it sounds like a possible factor.

    I repeated a simple draping simulation over 200 frames and it was a bit better but still the clothing intersected the figure. I would have thought that the draping process could include a step for each frame to move any polygons which intersect the collision object (eg the figure) outside the figure. Perhaps this would need to be followed by a smoothing process for the polys around the intersecting polys to avoid ugliness. 

    Subframes and Iterations per subframe allow you to put more work into each frame, without having to increase the frame count. The settings are discussed in the start here thread.

    IsaacNewton said:

    "Apparently the collision actually needs to be off, it isn't just a good idea off to preserve speed, because the changes made by the Smoothing Modifier Collision would confuse the dynamic simulation - adding extra movment (from smoothing) to the the speed and direction of movement used by the simulation, which would corrupt the process."

    Not sure what you are saying here. However, I thought that dForce switched off the Smoothing Modifer during the simulation process.

    Yes, I was passing on an explanation of why the Smoothing Modifier has to be switched off during simulation.

  • AndySAndyS Posts: 1,438
    Daywalker Designs said:
    Richard Haseltine said:

    dForce turns a Smoothing Modifier off, if present, and then back on again after completing the simulation. Is that what you mean? I don'tknow if there are other reasons not to run them in prallel but there'd be a hefty speed penalty if the Smoothing Modifier had to recaclculate after each simulation step (at least).

    I'm pretty sure he's talking about autofit collision or conforming.

    No,

    I'm talking about collision handling, not autofit.
    And dForce don't switch it on again afterwards. You have to do it manually.

  • barbultbarbult Posts: 24,775
    edited November 2017
    Richard Haseltine said:

    dForce turns a Smoothing Modifier off, if present, and then back on again after completing the simulation. Is that what you mean? I don'tknow if there are other reasons not to run them in prallel but there'd be a hefty speed penalty if the Smoothing Modifier had to recaclculate after each simulation step (at least).

    I haven't seen evidence of simulation turning Smoothing (the one in Parameters pane) off and back on. I have seen that adding a dForce modifier to objects that don't load with it, does turn Smoothing off, but I never see it get automatically turned back on. I need more clarification about how this is supposed to work.

    Also, the dForce clothing I've purchased load with Smoothing turned on. Can I simulate like that, or do I have to turn Smoothing off first and then back on after simulation?

    Post edited by barbult on
  • Richard HaseltineRichard Haseltine Posts: 102,436
    barbult said:
    Richard Haseltine said:

    dForce turns a Smoothing Modifier off, if present, and then back on again after completing the simulation. Is that what you mean? I don'tknow if there are other reasons not to run them in prallel but there'd be a hefty speed penalty if the Smoothing Modifier had to recaclculate after each simulation step (at least).

    I haven't seen evidence of simulation turning Smoothing (the one in Parameters pane) off and back on. I have seen that adding a dForce modifier to objects that don't load with it, does turn Smoothing off, but I never see it get automatically turned back on. I need more clarification about how this is supposed to work.

    Also, the dForce clothing I've purchased load with Smoothing turned on. Can I simulate like that, or do I have to turn Smoothing off first and then back on after simulation?

    I think it may not show in the UI - it's just while the simulation is running. There's nothing wrong with having smoothing on othrewise, the simulation doesn't do anything when the progress bar doesn't show it running.

  • barbultbarbult Posts: 24,775
    Richard Haseltine said:
    barbult said:
    Richard Haseltine said:

    dForce turns a Smoothing Modifier off, if present, and then back on again after completing the simulation. Is that what you mean? I don'tknow if there are other reasons not to run them in prallel but there'd be a hefty speed penalty if the Smoothing Modifier had to recaclculate after each simulation step (at least).

    I haven't seen evidence of simulation turning Smoothing (the one in Parameters pane) off and back on. I have seen that adding a dForce modifier to objects that don't load with it, does turn Smoothing off, but I never see it get automatically turned back on. I need more clarification about how this is supposed to work.

    Also, the dForce clothing I've purchased load with Smoothing turned on. Can I simulate like that, or do I have to turn Smoothing off first and then back on after simulation?

    I think it may not show in the UI - it's just while the simulation is running. There's nothing wrong with having smoothing on othrewise, the simulation doesn't do anything when the progress bar doesn't show it running.

    If don't manually turn off Smoothing before simulating, the simulation takes longer. I have a Wilmap top that I added dForce to. With Smoothing on, it took 7 minutes and 46 seconds to simulate. When I manually turned Smoothing off before simuling, the simulation took only 6 minutes and 8 seconds.

    I ran both simulations again and got nearly identical times. Leaving Smoothing on in the Parameters pane: 7 minutes 49 seconds. Manually turning Smoothing off in the Parameters pane: 6 minutes 6 seconds.

    It doesn't seem like Simulation is really turning Smoothing off, or is doing so in an inefficient way.

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