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, 3 insertions, 4 deletions

diff --git a/source/blender/editors/sculpt_paint/paint_utils.c b/source/blender/editors/sculpt_paint/paint_utils.c
index d470e6a3050..31b965c6a92 100644
--- a/source/blender/editors/sculpt_paint/paint_utils.c
+++ b/source/blender/editors/sculpt_paint/paint_utils.c
@@ -130,13 +130,12 @@ float paint_calc_object_space_radius(ViewContext *vc, const float center[3], flo
 {
   Object *ob = vc->obact;
   float delta[3], scale, loc[3];
-  const float mval_f[2] = {pixel_radius, 0.0f};
-  float zfac;
+  const float xy_delta[2] = {pixel_radius, 0.0f};
 
   mul_v3_m4v3(loc, ob->obmat, center);
 
-  zfac = ED_view3d_calc_zfac(vc->rv3d, loc, NULL);
-  ED_view3d_win_to_delta(vc->region, mval_f, delta, zfac);
+  const float zfac = ED_view3d_calc_zfac(vc->rv3d, loc);
+  ED_view3d_win_to_delta(vc->region, xy_delta, zfac, delta);
 
   scale = fabsf(mat4_to_scale(ob->obmat));
   scale = (scale == 0.0f) ? 1.0f : scale;