Mapping the Legs

[kariaro]

Mapping the Legs

[Kariaro]

Hi @Zumbalamambo

Thanks for the complements! :D

When I started writing the code I flipped left and right because I couldn't get the VRM model to render correctly when flipped.

I've not used any references when making my code so I can sadly not give you any sources but I can describe how I would solve this 👍

// Fetch data points from Mediapipe
Vector3 rHip   = ConvertPoint(eventArgs.value, 23);
Vector3 rKnee  = ConvertPoint(eventArgs.value, 25);
Vector3 rAnkle = ConvertPoint(eventArgs.value, 27);

We know that the default vector of the upperleg to the knee is pointing downwards, we want to calculate the deviation from that vector

// If we were standing normally this would (*when normalized*) be close to (0, -1, 0)
Vector3 rHipKneeDiff    = rKnee - rHip;
Vector3 rHipKneeDefault = Vector3.down;

// Calculate the rotation needed to go from (0, -1, 0) to hip-knee vector
Quaternion rHipRotation = Quaternion.FromToRotation(rHipKneeDefault, rHipKneeDiff);

// Normally the knee-ankle vector is pointing in the same direction as the hip-knee vector
Vector3 rKneeAnkleDiff    = rAnkle - rKnee;
Vector3 rKneeAnkleDefault = rHipKneeDiff;

// Calculating the knee rotation can be done similarly.
Quaterion rKneeAnkle = Quaterion.FromToRotation(rKneeAnkleDefault, rKneeAnkleDiff);

I've not tested this code but I would write something similar to this

[Zumbalamambo]

@Kariaro thank you! I have adopted the code as follows,

rUpperLeg = rHipRotation;
rLowerLeg = rKneeAnkle;

Later setting the instance variables as follows,

this.rUpperLeg.Set(rUpperLeg,TimeNow);
this.rLowerLeg.Set(rLowerLeg,TimeNow);

and applied it to the vrm ,

rLowerLeg.UpdateRotation(animator.GetBoneTransform(HumanBodyBones.RightLowerLeg), time);
rUpperLeg.UpdateRotation(animator.GetBoneTransform(HumanBodyBones.RightUpperLeg), time);

Unfortunately, the leg is twisted backwards. Am I missing something? thanks again!

[Kariaro]

Hi @Zumbalamambo

I think this might be because vectors do not keep the forward direction.
The forward vector could be computed from the knee direction relative to the hip. I won’t be able to help with code for the next few days because I will not be at my computer.

[Zumbalamambo]

@Kariaro thanks for the hint!