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, 2 insertions, 2 deletions

diff --git a/source/blender/editors/mesh/editmesh_bisect.c b/source/blender/editors/mesh/editmesh_bisect.c
index 58bd906101c..7b251b77750 100644
--- a/source/blender/editors/mesh/editmesh_bisect.c
+++ b/source/blender/editors/mesh/editmesh_bisect.c
@@ -77,14 +77,14 @@ static void mesh_bisect_interactive_calc(bContext *C,
   const float *co_ref = rv3d->ofs;
   float co_a_ss[2] = {x_start, y_start}, co_b_ss[2] = {x_end, y_end}, co_delta_ss[2];
   float co_a[3], co_b[3];
-  const float zfac = ED_view3d_calc_zfac(rv3d, co_ref, NULL);
+  const float zfac = ED_view3d_calc_zfac(rv3d, co_ref);
 
   /* view vector */
   ED_view3d_win_to_vector(region, co_a_ss, co_a);
 
   /* view delta */
   sub_v2_v2v2(co_delta_ss, co_a_ss, co_b_ss);
-  ED_view3d_win_to_delta(region, co_delta_ss, co_b, zfac);
+  ED_view3d_win_to_delta(region, co_delta_ss, zfac, co_b);
 
   /* cross both to get a normal */
   cross_v3_v3v3(plane_no, co_a, co_b);