Commit graph

4 commits

Author SHA1 Message Date
Matthew Waters
16cba63d43 gl/utils: fixup matrix math again for column major
e4bf9ed8f0 was not quite right and changed
the wrong thing. Intead we needed to change the multiplication order
and should have kept the previous to/from matrices as is done in this
patch.
2018-07-10 20:13:22 +10:00
Matthew Waters
8e641a9277 gl/tests: matrix use the affine matrix setter to convert matrices
Removes some duplicated matrices that didn't really need to be
hardcoded.
2018-06-21 17:47:09 +10:00
Matthew Waters
e4bf9ed8f0 gl/utils: Fix NDC conversion matrices for column-majorness
The matrices were converting the wrong values with non-diagonal-only matrices.
e.g. a typical yflip matrix in [-1,1]^3 such as
 1  0  0  0
 0 -1  0  0
 0  0  1  0
 0  0  0  1

Would have actually required a matrix like this in [0,1]^3
 1  0  0  0
 0 -1  0  0
 0  0  1  0
 0 -2  0  1

Which is
1. not consistent with our multiplication convention and would require
   transposing matrices or changing our multiplication order (from what is
   generally used on opengl matrix guides/tutorials).
2. Produces incorrect values when input with actual vertices accounting for
   the difference in multiplication order.  e.g. some vertices multiplied by
   the yflip matrix using vertex * yflip(== transpose(yflip) * vertex):

     vertex:       -> result:           expected:
     vec4(1,0,1,1) -> vec4(1,-2,1,1)    vec4(1,1,1,1)
     vec4(1,1,1,1) -> vec4(1,-3,1,1)    vec4(1,0,1,1)

With the updated values, we now get the expected values.

Includes a test for this behaviour and the example above
2018-06-06 23:36:08 +10:00
Matthew Waters
21252d450c glutils: fix matrix operations everywhere
- correct the matrix multiplication
- Use column-major matrices
  - reverse order of matrix multiplications

https://bugzilla.gnome.org/show_bug.cgi?id=785980
2017-12-09 19:32:30 +00:00