Anim8or Community

I regularly use Anim8or to produce models for 3D printing.  I designed many upgrade parts for my 3D printer in Anim8or, and then printed them on my Kossel 3D printer.  I like designing my robot prototypes in Anim8or because I can then animate the robot to see if the parts will actually go together and move correctly before I print them.

I have attached a zip file containing the VB 2013 source code for the SMDtoAnim8or converter.  The previous executable I posted was written in VB6.  I did the minimum required to port it to VS 2013 VB and tested it to be sure it works.

The source code for the converter (especially the parsing routines) is very inefficient in VB.net terms given it is minimally changed from VB6.  There are nice parsing libraries available in VB.net, but I did not take the time to implement them.

VS 2013 Community version is free (takes forever to install) if you want to compile or modify it. 

In this converter, unlike the BVH converter, the program calculates the joint offsets, then the figure's bone orientation from the offsets.  I implemented it this way since the SMD format is not in hierarchical format (unlike BVH), so the parent/child relationships are not known until all the bones are read.  It was easier to calculate the offsets first (in this case), then the orientation rather than the other way around.  The math concepts are the same.

I explained the difficulties in writing this kind of converter in http://www.anim8or.com/smf/index.php/topic,4861.msg36976.html#msg36976

NickE

Converting other animation files to Anim8or is complicated not because of the math, but because the other animation formats have different skeleton standards and frames of reference.  The first hurdle in converting formats is finding a way to correlate the foreign skeleton to an Anim8or skeleton.  I found this to be the most challenging part because of two things: (1) most foreign formats use joints and Anim8or uses bones, and (2) the reference frames of foreign formats differs from Anim8or's.  Once you solve the correspondence of foreign joints/bones to Anim8or's bones, you must deduce the the difference in world reference frames and rotate the skeleton into Anim8or's world reference frame.

The next challenge is deducing the reference frame of the foreign bone's orientation.  In Anim8or, the orientation of each bone is relative to the parent (BVH and SMD are similar in that respect), but the reference frame in Anim8or is y-axis along the bone, left-handed axis system.  What is the foreign format reference frame axis system?

The foreign format's often give Euler angles for orientation, but does it use XYZ, YXZ, ZYX or other order?  This must be deduced.  Internally, Anim8or uses quaternions, so Euler to quaternion conversions must be done.  The math for this conversion is different depending on what the world and local reference frame axis systems are.

These problems, coupled with the brain-twisting non-intuitiveness of quaternions will make your brain explode!  Each part of the conversion of a foreign format to Anim8or's is dependent on the previous part.  You can get all but one step correct and the result will look as wrong as getting them all wrong.

The math (and code for the math) itself is fairly straightforward.  Pretty much everything you need to know math-wise can be found on Martin Baker's site http://www.euclideanspace.com/maths/geometry/

MvGulik,

Good catch!  Thank you so much!

NickE

Deepthought,

Is it your intention to (1) gain the experience and satisfaction of having written a converter for SMD files for Anim8or or (2) do you just want something that works?

If (1), then you need to gain a thorough understanding of the both the SMD file format(s) and reference frames and Anim8or's conventions for handling figures, sequences, and scenes.  The code in the BVH converter is not going to make sense unless you understand those concepts.  In a nutshell, the code reads and parses a BVH file, constructs an Anim8or figure, constructs a sequence for the non-positional movements, and then constructs a scene containing the figure and sequence so that position can be added.  In Anim8or, the figure's root bone is relative to the world coordinate system, but each child bone is relative to it's parent.  A cursory reading of the SMD format suggests the same arrangement (although it is not completely clear), but the world coordinate system is different from Anim8or's.

The math part essentially steps through the bones, rotates the bones into the reference frame, performs the relative rotation of child to parent, then rotates them back.

If (2), I'd be happy to help you out if you can be patient.  I would need some sample SMD's and either some viewer program or screenshots to see what the SMD file is supposed to look like.  My first guess is that the BVH conversion program can be easily adapted by writing a new parsing routine and other small changes.

NickE

Attached is a script to generate Metric Screws and Nuts.  Currently supported are Socket Head, Button Head, and Hex Head.

Enjoy!

NickE

Attached is a parametric script to generate allthread.  The thread profile is based on the ISO Metric Thread Standard.  You can edit the script to give other thread profiles.

Enjoy.

NickE

Steve,
   Thank you for continuing to support Anim8or.  I use it almost on a daily basis. 

Bugs to report:

1) Builds 1086 to 1115: Loss of Precision in Orientation in Object Editor:  If orientation is set in the "Parameters" dialog box to a value, the value is changed to a lower precision number when the dialog is reopened. 
   For example:
      A cylinder is drawn randomly
     "Cylinder Parameters" dialog box is opened by double-clicking the cylinder
     I change the "Orientation (PYR)" to 90,0,0 and "OK" is clicked
     "Cylinder Parameters" dialog box is opened by double clicking the cylinder
     The values shown are 89.966,-0.000,-0.000 and the cylinder looks as if the orientation has noticably changed
     
This is mostly likely due to the variable types being used in the quat-to-PYR function and/or the PYR-to-quat function.  Should be a quick fix.

2) Builds 1112 to 1115: Figure editor will not allow moving, rotating, or scaling of objects attached/added to bones.

3) Builds 1112 to 1115: Any mouse dragging for movement, rotation, scaling, etc on a group in Object Editor will crash Anim8or.  Double-clicking to open the "Group-Parameters" dialog works without crashing.

Thank you!