Yet even more MHX constraints stuff (and some deformations)

[joepal]

Looking through the recent constraint changes, much feel a lot more natural now, especially in the lower legs / foot section. It also feels natural to have some restrictions in spine / neck bending.

So I'm continuing my testing, cause it's easier to sit and look for things to complain about than actually change stuff oneself.

First an arm problem. I'm trying to make a guy in a classic "hands up" pose, ie elbows bent 90 degrees, hands straight up. These are the problems I run into:

First, we bend elbow 90 degrees by moving "Human LoArmFK_L". This works fine:

( Full resolution: http://www.jwp.se/files/armrot1.png )



Then we have to rotate using upper arm "Human UpArmFK_L". However, this is restricted to 45 degrees:

( Full resolution: http://www.jwp.se/files/armrot2.png )



Furthermore, while we're at it (and I know you mentioned it before too), even a 45 degree rotation seriously messes up shoulder:

( Full resolution: http://www.jwp.se/files/armrot3.png )



Still, I'd suggest increasing rotation range to 90 degrees upwards, and maybe 45 degrees downwards. Another idea would be to allow rotation of "Human Shoulder_L" around X, although waving around my own arms (probably looking like some breakdancer or generally nuts to anyone looking in through the windows), it doesn't feel as the shoulder really moves in the -45 to +90 range. However, if rotating more than 45 downward or more than 90 upwards, the shoulder starts to move.

The deformation is a later weight paint problem I guess.

While I was at it I went through the leg rotations, and as said the rotations feel a lot more natural now. However, there's something seriously wrong with the deformation at the top of the upper leg in a "sitting" pose:

( Full resolution: http://www.jwp.se/files/legbend1.png )



( Full resolution: http://www.jwp.se/files/legbend2.png )



Can't say I really know how it should look instead, but this looks a bit unnatural, the crease becomes too marked for a 90 degrees rotation. Rotating more or less it looks more natural though.

[ThomasL]

Hi Joel. I almost missed your post; your feedback is very valuable.

The left and right upper-arm Y limits were interchanged. Easily fixed, but I won't make any commits until all alpha 5.1's are ready. We don't want alpha 5.1 on different platforms to be incompatible.

The shoulders and hips are the most difficult to get to deform nicely. The problem is that they are ball joints which can rotate independently around all three axes, and it is difficult to paint weights that work for all axes and angles. E.g., a weighting that works if the thigh is rotated forward may lead to very strange results if it is rotated outwards or back. I have looked into various books, but not really understood what the best practice is; most books are written for Maya which have a quite different rigging philosophy than Blender.

One idea that I have tried repeatedly is to use corrective shapekeys. Accept that the deformation is poor, and then fix it by adding a shapekey driven by bone rotations. Unfortunately, I have not managed to make shapekeys that look good. What makes thing extra difficult for MH is that the same morphs must work for all characters, although they were made for the default character. Dwarfs are especially nasty.

However, I agree that something has to be done about deformation. Perhaps when the targets from the pose engine are ready, one can use them to build character-specific shapekeys, although it is not clear to me now how to implement that. In the short run, one should rerig and reweight the shoulder area and the neck, at least.

[Marbury Intermedia]

I wish I could be of some help. I'm still getting hit and miss results, and I have not moved into Blender 2.5 yet.