pluggable element-wise matrix operations

[thi-ng]

pluggable element-wise matrix operations

[postspectacular]

Hi Kovas, just to make sure I understand that correctly.. are you're asking if the matrix types could be used like this:

(let [a (matrix44 ...)
      b (matrix44 ...)]
  ;; produce new matrix via elementwise combination
  (combine a b +))

Indeed that would be quite nice to have and not hard to implement... Also happy about other naming proposals instead of combine or combine-with.

[kovasb]

My specific use case is for generating matrix transformations for use inside of gamma shaders.

I'd like to do something like
(geom/rotate-around-axis [gamma-x-coord gamma-y-coord ...] [0 1 0] rad)

where gamma-x-coord etc are datastructures representing GLSL fragments. I would supply my own functions for +, -, *, / which would take the args and generate a new GLSL frag. Then I would take the resulting structure and transform it into actual GLSL.

This is basically symbolic manipulation. In general it could also be used without gamma to symbolically generate clojure code that just computes the desired end structure with no intermediate allocations.

There is https://github.com/clojure-numerics/expresso, but it doesn't have the builtins that I need, and probably doesn't follow the same graphics-friendly conventions as thi-ng.

As a side note, there is a different approach to removing allocations from geometry generation pipeline (not applicable to the shader-side stuff I'm talking about above) in the newly-released mathbox2

gitgud.io/unconed/mathbox
http://acko.net/blog/mathbox2/

based on transducer-like idea of calling a supplied "emit" function with every step of the transformation. Pretty interesting.