Re:Matrices can be your Friends
by a_e_k on Monday October 13, 2025 @01:23PM
(#45570961)
This is one of those things that's perennially annoying in computer graphics. Depending on the API you can have different conventions for:
- data layout (row-major vs. column major)
- pre-multiplication vs. post-multiplication of matrices
Switching either of these conventions results in a transposition of the data in memory, but knowing which one you're switching is important to getting the implementation of the math right.
And then on top of that for even more fun you have:
- Left- vs. right-handed coordinate systems
- Y-up or Z-up
- Winding order for inside/outside
There are lots of small parity things like this where you can get it right by accident but then have weird issues down the line if you aren't scrupulous. (I once had a very tedious time tracking down some inconsistencies in inside/outside determination in a production rendering system.)
- data layout (row-major vs. column major)
- pre-multiplication vs. post-multiplication of matrices
Switching either of these conventions results in a transposition of the data in memory, but knowing which one you're switching is important to getting the implementation of the math right.
And then on top of that for even more fun you have:
- Left- vs. right-handed coordinate systems
- Y-up or Z-up
- Winding order for inside/outside
There are lots of small parity things like this where you can get it right by accident but then have weird issues down the line if you aren't scrupulous. (I once had a very tedious time tracking down some inconsistencies in inside/outside determination in a production rendering system.)