[Advanced]BVH problems.

[Farabi]

I was wondering, why at the bvh file it writen someting like this for the euler angle -2.55 -4.82 -16.27 but on blender the right euler angle value is -5 -16 -1.104 . Anyone experienced with this? I uploaded the bvh parser file. I've recheck the parser many time and all of the loaded value was just fine, I was just wondering why the value at the file is different at the final result value, what am I missed.

[dedndave]

that's a lot of material to read through - lol

maybe you are not reading the correct file offsets - or it could be your bvh file
best i can do without spending a lot of time on it is give you a couple links to check against

http://research.cs.wisc.edu/graphics/Courses/cs-838-1999/Jeff/BVH.html
http://www-scf.usc.edu/~amahajan/mocap/code.html

that first link has an example bvh file

[Farabi]

Ive checked all the value loaded and Its right. I loaded it based on the file provided it. problem is, the value written on blender is isnot on the file. i might missed some calculation.

[Farabi]

here is how you draw the bvh node

Code Select Expand



.data

invoke glPushMatrix
invoke glTranslatef,FP4(0.),FP4(1.),FP4(0.)
invoke fBVHDrawNode,addr hm2,0
invoke glPopMatrix


put this on initialization code and call it once

Code Select Expand


; here is where all node is processed
xor ecx,ecx
loop_frame:
push ecx
invoke fBVHProcessNode,addr hm2,ecx
pop ecx
inc ecx
cmp ecx,hm2.nFrameCount
jl loop_frame


fBVHProcessNode will rotate all the node based on the value given provided on the file, the problem is, the rotation from the file is different than yielded by blender, I must be miss some calculation in there. I opened my old project and found this code and my curiousity suddenly reawaken, if Im not mistaken I've abandon this since 2008.

[Farabi]

https://www.asuswebstorage.com/navigate/s/DF7D1ECB7FFE490F8388A9EA16A52C25Y

I think I done it.
Looks right for me. I never though rotating it from X-Y-Z order is different than -Z-X-Y order. I need to build a matrix following that order.

[Farabi]

Yep it worked. Now I go to the next step, skinning. This should be easier than before. I've been studying this for 3 years but never understand it, after I understood the matrix and how 3D math worked, suddenly I understand everything. Now I've understand everything even I confident i can make a 3D graphic engine from scracth. Maybe if someday I have a programable GPU I will make my own 3D graphic engine. OpenGL is really usefull and easy to understand, I think I understand everything because of using OpenGL. OpenGL is a lowlevel of 3D programming concept.

[xanatose]

Not sure if you are already doing it, but:

Try using quaternions for interpolation.
http://en.wikipedia.org/wiki/Quaternion
http://www.gamasutra.com/view/feature/3278/rotating_objects_using_quaternions.php

This will avoid gimbal locks http://en.wikipedia.org/wiki/Gimbal_lock

Look also for fast quaternion slerp (Sperical Linear Interpolation). They can be quicker than real slerp with no noticeable difference on the outcome.

[Farabi]

I never heard bvh file processed using quaternion. Beside the rotation data is euler angle. But thanks for the link. I just need to do the skinning process.