transform_vec doesn't do what you'd expect
eira-fransham opened this issue · 3 comments
The standard behaviour for multiplying a 3x2 matrix by a 2-element vector in game/graphics programming is to one-fill the 2-element vector to a 3-element vector. This allows you to translate the vector cheaply and easily.
What graphics::math::transform_vec does, however, is zero-fill the 2-element vector. This means that any position is simply ignored. This is really unintuitive and led to a 3-hour debugging session for me (although I had other bugs in my code that were fixed along the way, so it's not all bad).
Use transform_pos.
It would probably be good to write this in the documentation for transform_vec, since at the moment the only way to discover this is via looking at the source (and understanding enough vector maths to know the problem) or via this issue.
Opened PistonDevelopers/vecmath#279