# Question on 3D maths required for a simulation. [closed]

I am a community member at the Planetary Annihilation forums and we seem to be in a bit of a pickle.

The problem is, the modding community currently cannot export skeletons from Blender -> the native PA file format (.papa) due to the 3d math knowledge needed to get the export working for bones that have been rotated, and contain rotations in their animation frames. (The discussion can be found here.)

I was wondering if the community here could help me figure out where we might be able to get help on this issue. How can I ask the question at Math.SE so that it shall be on-topic or well-received.

• In the present form this does not seem to be a suitable question for Math.SE. Consider that there is Blender, a Stack Exchange site for Blender. Also, a question should be as self-contained as possible: expecting users to read a forum thread elsewhere is unrealistic.
– user147263
Commented Oct 28, 2014 at 1:59
• Yea sorry if I didn't properly format this question. :( Commented Oct 28, 2014 at 2:14
• Who voted to reopen this? Commented Oct 29, 2014 at 2:23
• @anorton. I voted. I disagree with "This question does not appear to be about Mathematics Stack Exchange ..." (at least in it's current form.) Commented Oct 31, 2014 at 12:30

If you wish to post the question on Math.SE then try to reduce your original problem into something more suitable for the community. For example, Calculate Rotation Matrix to align Vector A to Vector B in 3d?

I have one triangle in 3d space that I am tracking in a simulation. Between time steps I have the the previous normal of the triangle and the current normal of the triangle along with both the current and previous 3d vertex positions of the triangles.

Using the normals of the triangular plane I would like to determine a rotation matrix that would align the normals of the triangles thereby setting the two triangles parallel to each other. I would then like to use a translation matrix to map the previous onto the current, however this is not my main concern right now.

I have found this website http://forums.cgsociety.org/archive/index.php/t-741227.html that says I must

• determine the cross product of these two vectors (to determine a rotation axis)
• determine the dot product ( to find rotation angle)
• build quaternion (not sure what this means)
• the transformation matrix is the quaternion as a 3 by 3 ( not sure)

If your question requires a lot of time and effort to answer, consider awarding a bounty.

Alternatively, there is a Game development Stackexchange which has mathematics and 3d tags. Weapon of choice mentions Blender Stackexchange (which is currently is beta).