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, 9 insertions, 10 deletions

diff --git a/source/blender/editors/gpencil/gpencil_sculpt_paint.c b/source/blender/editors/gpencil/gpencil_sculpt_paint.c
index ebe879959c9..67325e8a3d1 100644
--- a/source/blender/editors/gpencil/gpencil_sculpt_paint.c
+++ b/source/blender/editors/gpencil/gpencil_sculpt_paint.c
@@ -507,7 +507,7 @@ static void gpencil_brush_grab_calc_dvec(tGP_BrushEditData *gso)
   /* Convert mouse-movements to movement vector */
   RegionView3D *rv3d = gso->region->regiondata;
   float *rvec = gso->object->loc;
-  float zfac = ED_view3d_calc_zfac(rv3d, rvec, NULL);
+  const float zfac = ED_view3d_calc_zfac(rv3d, rvec);
 
   float mval_f[2];
 
@@ -525,7 +525,7 @@ static void gpencil_brush_grab_calc_dvec(tGP_BrushEditData *gso)
     copy_v2_v2(mval_f, r);
   }
 
-  ED_view3d_win_to_delta(gso->region, mval_f, gso->dvec, zfac);
+  ED_view3d_win_to_delta(gso->region, mval_f, zfac, gso->dvec);
 }
 
 /* Apply grab transform to all relevant points of the affected strokes */
@@ -624,17 +624,16 @@ static void gpencil_brush_calc_midpoint(tGP_BrushEditData *gso)
    */
   RegionView3D *rv3d = gso->region->regiondata;
   const float *rvec = gso->object->loc;
-  float zfac = ED_view3d_calc_zfac(rv3d, rvec, NULL);
+  const float zfac = ED_view3d_calc_zfac(rv3d, rvec);
 
-  float mval_f[2];
-  copy_v2_v2(mval_f, gso->mval);
   float mval_prj[2];
-  float dvec[3];
 
   if (ED_view3d_project_float_global(gso->region, rvec, mval_prj, V3D_PROJ_TEST_NOP) ==
       V3D_PROJ_RET_OK) {
-    sub_v2_v2v2(mval_f, mval_prj, mval_f);
-    ED_view3d_win_to_delta(gso->region, mval_f, dvec, zfac);
+    float dvec[3];
+    float xy_delta[2];
+    sub_v2_v2v2(xy_delta, mval_prj, gso->mval);
+    ED_view3d_win_to_delta(gso->region, xy_delta, zfac, dvec);
     sub_v3_v3v3(gso->dvec, rvec, dvec);
   }
   else {
@@ -830,10 +829,10 @@ static bool gpencil_brush_randomize_apply(tGP_BrushEditData *gso,
       /* 3D: Project to 3D space */
       bool flip;
       RegionView3D *rv3d = gso->region->regiondata;
-      float zfac = ED_view3d_calc_zfac(rv3d, &pt->x, &flip);
+      const float zfac = ED_view3d_calc_zfac_ex(rv3d, &pt->x, &flip);
       if (flip == false) {
         float dvec[3];
-        ED_view3d_win_to_delta(gso->gsc.region, svec, dvec, zfac);
+        ED_view3d_win_to_delta(gso->gsc.region, svec, zfac, dvec);
         add_v3_v3(&pt->x, dvec);
         /* compute lock axis */
         gpencil_sculpt_compute_lock_axis(gso, pt, save_pt);