Cult of Rig : Season 00 Day 005 – Vectors

Note : There isn’t much breakdown on this, as you really need to watch it through and pay attention, enjoy!

Season 00 Day 005 Stream – Vectors

Math time! ( need more reference check our math resources for more )

“Day five: a crash course in vector math basics all the way to practical application, at which point a crash in input devices all the way to mouse click prevented actual practical application.

Minute 52 to 58 are largely pointless, once you get to 52m just skip ahead to this point in the video:
Sadly as of two months ago YouTube doesn’t allow annotating any longer, so I can’t inline this in the video itself like you might have seen elsewhere.”

  • Why vectors? Problem with the rig right now is you can’t twist the rig as everything pivots from a diffrent location/offsets. That is normal but want to cover vectors before we get to the fixes.
  • Not a rotation issue – it is a translation issue ( the rotations are linked well but they don’t translate when rotated, the position is still added in world space, not the local space
    • Simple fix? add in some extra nodes under localWorld_srt – world2pedals_offset_srt and match that offset to the center of the wheel, then grab its world space in push it in to the pedals_M_staff_ctrl_srtBuffer

Why does this work?because there is a real transform node located at the correct place that is now rotated by the control.  This is fine but great, what about if we want to keep the rig in the node graph and not hiearchy hacking?

Intro to Maths

  • vectors
  • linear algebra
    • when you want to work on two numbers together like X and Y you use linear algebra
  • the meeting location of the 2 numbers (X,Y) gives you a direction aka 2d vector

In Maya you get a Vector (xyz) and a Point (xyzw)where the w is the length of travel down the vector until you hit the point location.

  • What can you do to the vectors?
    • Add the 2 of them them piece wise ( each value) per part X/Y/Z
    • Subtract them but remember order of operation matters to go in the correct direction along the vector
    • Multiply them
    • Vectors of length 1 (normalized or normal vector) and how the Pythagorean theorem works to find it.


Then Maya crashed and took the stream to QA 🙂 but the rest of this is in the next video and our next breakdown as you should watch next!

QA: Use case for this math stuff?



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