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The point of twist/bend joint options?

fred9803fred9803 Posts: 1,565
in The Commons

In the scene hierarchy there are options to select bend or twist [bones?].

But it doesn't seem to matter which I select because when I use the parameter dials for twist or bend the joint the effect is the same regardless of which I have chosen in scene hierarchy.

By this I mean if I select "left forearm bend", it will move the same when I twist or bent it compared to if I had selected "left forearm twist".

Comments

  • kaotkblisskaotkbliss Posts: 2,914

    I'm curious as well.

    At first I thought it was each bone influencing different parts of the mesh and the sliders just linked together, but then why not just make them 1 bone then...

  • Serene NightSerene Night Posts: 17,704

    I use twist in the upper arm often to adjust the lower arm. I don’t see them as the same.

  • kaotkblisskaotkbliss Posts: 2,914

    He means the two bones in the upper arm (or two bones in the lower arm) the two bones in the same arm section do the same thing. So why 2 bones in the upper arm and 2 bones in the lower arm?

    If you rotate the shoulder twist it does the same thing as rotating the shoulder bend and you can see this by checking the sliders in both after adjusting, they are set the same.

  • Serene NightSerene Night Posts: 17,704

    Ah, I misunderstood. Maybe they had intended additional funtionality at one time.

  • HavosHavos Posts: 5,578

    I believe the difference is related to Genesis 3 and 8 use of Dual Quatrion weight mapping. My understanding is that the twist and bend actions requires different weight maps, and this is handled using these two bones, even though from a user perspective, the bones do the same thing. I am no expert on weight mapping, so I could be wrong in this, but I know that Genesis and Genesis 2 did not need this, as their weight mapping allowed up to 3 different weight maps per bone.

    It is a shame that this largely technical detail could not be hidden from the user.

  • fred9803fred9803 Posts: 1,565

    So basically it doesn't matter which you select because the parparameter dials will do the same thing with either bend or twist selected. I'll continue to select either one depending on my mood... if I feel like a twisty I'll choose that one, or a bendy if the mood suits me LOL. Built-in obsolescence.

  • Richard HaseltineRichard Haseltine Posts: 108,028

    It's the switch to general weight mapping, instead of triAx, that is the issue - general weight mapping is more widely used (I'm not sure anything other than Poser adn DS has used a separate map for each axis), but it does mean that bends (which affect only the joint) and twists (which affect the whole length of the bone) need separate sets of influence weights. For the Genesis 3 and 8 figures the properties are cloned, so that setting twist on the bend bone in fact adjusts the twist boen and setting one of the bends on the twist bone in fact affects the bend bone.

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