Cleanup: ED_view3d_win_to_delta & ED_view3d_calc_zfac usage

- Rename ED_view3d_win_to_delta `mval` argument to `xy_delta` as it
  as it was misleading since this is an screen-space offset not a region
  relative cursor position (typical use of the name `mval`).
  Also rename the variable passed to this function which also used the
  term `mval` in many places.
- Re-order the output argument of ED_view3d_win_to_delta last.
  use an r_ prefix for return arguments.
- Document how the `zfac` argument is intended to be used.
- Split ED_view3d_calc_zfac into two functions as the `r_flip` argument
  was only used in some special cases.

1 files changed, 1 insertions, 2 deletions

diff --git a/source/blender/editors/transform/transform_constraints.c b/source/blender/editors/transform/transform_constraints.c
index 64ef170a13f..81b35e4539b 100644
--- a/source/blender/editors/transform/transform_constraints.c
+++ b/source/blender/editors/transform/transform_constraints.c
@@ -1041,8 +1041,7 @@ static void setNearestAxis3d(TransInfo *t)
    * and to overflow the short integers.
    * The formula used is a bit stupid, just a simplification of the subtraction
    * of two 2D points 30 pixels apart (that's the last factor in the formula) after
-   * projecting them with ED_view3d_win_to_delta and then get the length of that vector.
-   */
+   * projecting them with #ED_view3d_win_to_delta and then get the length of that vector. */
   zfac = mul_project_m4_v3_zfac(t->persmat, t->center_global);
   zfac = len_v3(t->persinv[0]) * 2.0f / t->region->winx * zfac * 30.0f;