Dynamic cloth under stress



  • @Ladonna Just for the records: I did no postwork. Not with the morphbrush, not on the rendered image. Anything shown is what Poser has produced all alone :).



  • @anomalaus said in Dynamic cloth under stress:

    @adp have you done much constraint-wise? Like top of shoulder straps and waist-band, or is it all dynamic? Is the button just a hard decoration, or have you modeled actual button holes and threads?

    A bit more about this. Each clothpiece has a border (hem?) around all openings. This border simulates thickness.
    The innermost vertices of that border are defined as soft-decorated dynamic group. the outer vertices of that border are another dynamic group. The parameters for this group makes it a bit harder, stiffer as the rest.The dyn-engine obeys that and a real good looking hem/border is the result.



  • Here are some details to show mesh density.
    0_1531050777724_Bildschirmfoto vom 2018-07-08 13-47-47.png
    As you can see, the density of the dress is not mutch higher than (relatively low-res) Roxie's. And you can see the buttonborder connected with the 3 buttons (defined as rigid-decorated) holding anything together.

    0_1531050948784_Bildschirmfoto vom 2018-07-08 13-50-55.png
    The trousers are a bit higher in density because they are tighter and has to support smaller folds.



  • @eclark1849 said in Dynamic cloth under stress:

    Now that I think about it, I started using the Cloth Room with Poser 6. I had skipped P5, so P6 was the first version I ever used the Cloth Room in. And if I recall correctly it was the one that came with a Cloth Room tutorial. I may even still have it on my Mac.

    I can't remember since when I use the cloth room. But my first dynamic freebee at ShareCG is now 11 years old :)



  • Looks like I was wrong. The Tutorial was in Poser 7.



  • Another screenshot from the front.
    In the final version, I will add another one or two polygonrows to the buttonborder. To make sure the buttons have more "grip". At the moment, if the fabric has to less weight the buttons aren't able to hold it together.
    0_1531055233048_Bildschirmfoto vom 2018-07-08 15-05-22.png
    I'll upload the whole thing to ShareCG if I'm satisfied. May last a few days, because I'm busy with a Python script to export/import a figure as unimesh OBJ (as long as vertexcount stays unchanged) :)



  • The breast area has a higher density to support big ... I think you now why. Drawback here: the dyn-engine assumes that a higher poly-density means higher fabric-weight. Anytthing is good as long as this area is "stretched". With standard breastsize the fabric tends to sag in this area.



  • @adp
    I do not think it is a weight issue. It looks more like there is more shape in the mesh in the area than the figure can fill.
    If you assume shape is made by stretch, (in real life fabric this usually means ther are no darts or figure-seams) best start from a fit for a flat-chested figure and let the breasts 'grow in' by morph.



  • @F_Verbaas Here is how the mesh flows around the figure. I think it is tight enough (I looked sharp at a real model how cloth wraps around a body :)).

    0_1531057506527_Bildschirmfoto vom 2018-07-08 15-44-52.png



  • @F_Verbaas said in Dynamic cloth under stress:

    @adp
    I do not think it is a weight issue. It looks more like there is more shape in the mesh in the area than the figure can fill.
    If you assume shape is made by stretch, (in real life fabric this usually means ther are no darts or figure-seams) best start from a fit for a flat-chested figure and let the breasts 'grow in' by morph.

    Not "weight" but elasticity. But the size of the polygons in the area are a factor too. The farther apart the vertices have to move apart, the harder it is for the polygons to hold their shape and bend, so poke thrus occur. More polygons equals better elasticity and better bending and stretching.



  • @adp
    I take it this is before the simulation? And the fabric that covers the breast sags a little during the simulation?



  • @fverbaas Yes, before the sim. If cloth-density is set too light, you can identify the denser area. I think it has something to do with air-damping.



  • It is a common phenonenon. Let me try to explain.
    The simulation starts without strain in the garment so there is no pressure of the garment on the figure, so also no friction. There is however gravity pulling the garment down. Initially there is no force to counteract gravity, so gravity does its work and the garment begins an acceleration in the downward direction. In the second step, there is a velocity in the negative-y direction. In the third step there is a displacement in the -y direction, so strain may begin to build up, friction builds up, and the two begin a battle against gravity. It takes some time first to build up counter force against gravity and then to reduce velocity until the garment can begin the way back up, that is, if the garment is not caught in the lowest position (max pressure so max friction)!!. In the mean while substantial sag has built up, which will have made the 'cup' in the garment slide down off the breast, leading to a void below the breast point.
    The fabric dome spanning the void is likely to collapse under the load, and that is what you see: a mis-aIigned collapsed preform 'cup' in the fabric.
    In real life the fitter would lift and 'pluck' the garment a little to make the cup return to its position. Poser clothroom does not have such a 'plucking' possibility.
    The solutions? Not one in general that is perfect but a few things that will help:

    • Make gravity come in slowly in the sim.

    • Use constrained vertices

    • Use flat clothing and build breast shape in the course of the sim.

    Have fun.



  • @fverbaas Thanks.



  • This is working well. Following with interest.



  • @englishbob said in Dynamic cloth under stress:

    This is working well. Following with interest.

    You and me both :)



  • I think I have it now. Dynamic trousers under heavy stress:
    0_1531817229460_Trousers-A18.png

    No constrained or choreographed groups at all!
    0_1531817247304_Trousers-A15.png

    Because there is nothing constrained, in this pose the waistband is pulled down at the back. Like in real. And note: The waistband keeps it's form!
    0_1531817270671_Trousers-A14.png



  • There are intersections in the figures. On thigh/shin and tigh/hip/abdomen. The figure is a standard Roxie, no morphs used, just posed.

    0_1531818822654_Bildschirmfoto vom 2018-07-17 11-08-32a.png
    0_1531818833553_Bildschirmfoto vom 2018-07-17 11-10-26a.png



  • Before someone asks: No postwork, no morphbrush used, simple shader without bumpmap or displacement.



  • @adp said in Dynamic cloth under stress:

    There are intersections in the figures. On thigh/shin and tigh/hip/abdomen. The figure is a standard Roxie, no morphs used, just posed.

    Not necessarily. Remember that there is a minimum distance of space between the cloth and the figure and that space is measured in centimeters. The only way to know for sure if there is intersection is to push the camera inside the figure from the other side to see.