Fix T86073 : Ctrl clicking 3 times without selecting any of the verts in NurbsPath leads crash.

Crash occurs at `assert(builder->index_len < builder->max_index_len)`.

Non-bezier nurbs were being created with abnormal values causing the
causing edge count in the draw manager to be incorrect.

This commit also deduplicates and adds descriptions to the code.

Thanks @PratikPB2123 for pointing out where the error is.

1 files changed, 27 insertions, 42 deletions

diff --git a/source/blender/editors/curve/editcurve.c b/source/blender/editors/curve/editcurve.c
index c3ec87dc0d9..4816a432376 100644
--- a/source/blender/editors/curve/editcurve.c
+++ b/source/blender/editors/curve/editcurve.c
@@ -5446,29 +5446,33 @@ static int ed_editcurve_addvert(Curve *cu,
     /* nothing selected: create a new curve */
     Nurb *nu = BKE_curve_nurb_active_get(cu);
 
-    if (!nu || nu->type == CU_BEZIER) {
-      Nurb *nurb_new;
-      BezTriple *bezt_new;
+    Nurb *nurb_new;
+    if (!nu) {
+      /* Bezier as default. */
+      nurb_new = MEM_callocN(sizeof(Nurb), "BLI_editcurve_addvert new_bezt_nurb 2");
+      nurb_new->type = CU_BEZIER;
+      nurb_new->resolu = cu->resolu;
+      nurb_new->orderu = 4;
+      nurb_new->flag |= CU_SMOOTH;
+      BKE_nurb_bezierPoints_add(nurb_new, 1);
 
-      if (nu) {
-        nurb_new = BKE_nurb_copy(nu, 1, 1);
+      if ((cu->flag & CU_3D) == 0) {
+        nurb_new->flag |= CU_2D;
+      }
+    }
+    else {
+      /* Copy the active nurb settings. */
+      nurb_new = BKE_nurb_copy(nu, 1, 1);
+      if (nu->bezt) {
         memcpy(nurb_new->bezt, nu->bezt, sizeof(BezTriple));
       }
       else {
-        nurb_new = MEM_callocN(sizeof(Nurb), "BLI_editcurve_addvert new_bezt_nurb 2");
-        nurb_new->type = CU_BEZIER;
-        nurb_new->resolu = cu->resolu;
-        nurb_new->orderu = 4;
-        nurb_new->flag |= CU_SMOOTH;
-        BKE_nurb_bezierPoints_add(nurb_new, 1);
-
-        if ((cu->flag & CU_3D) == 0) {
-          nurb_new->flag |= CU_2D;
-        }
+        memcpy(nurb_new->bp, nu->bp, sizeof(BPoint));
       }
-      BLI_addtail(&editnurb->nurbs, nurb_new);
+    }
 
-      bezt_new = nurb_new->bezt;
+    if (nurb_new->type == CU_BEZIER) {
+      BezTriple *bezt_new = nurb_new->bezt;
 
       BEZT_SEL_ALL(bezt_new);
 
@@ -5480,40 +5484,21 @@ static int ed_editcurve_addvert(Curve *cu,
       temp[2] = 0.0f;
 
       copy_v3_v3(bezt_new->vec[1], location);
-      sub_v3_v3v3(bezt_new->vec[0], bezt_new->vec[1], temp);
-      add_v3_v3v3(bezt_new->vec[2], bezt_new->vec[1], temp);
-
-      changed = true;
+      sub_v3_v3v3(bezt_new->vec[0], location, temp);
+      add_v3_v3v3(bezt_new->vec[2], location, temp);
     }
     else {
-      Nurb *nurb_new;
-      BPoint *bp_new;
-
-      {
-        nurb_new = MEM_callocN(sizeof(Nurb), __func__);
-        nurb_new->type = CU_POLY;
-        nurb_new->resolu = cu->resolu;
-        nurb_new->flag |= CU_SMOOTH;
-        nurb_new->orderu = 4;
-        BKE_nurb_points_add(nurb_new, 1);
-
-        if ((cu->flag & CU_3D) == 0) {
-          nurb_new->flag |= CU_2D;
-        }
-      }
-      BLI_addtail(&editnurb->nurbs, nurb_new);
-
-      bp_new = nurb_new->bp;
+      BPoint *bp_new = nurb_new->bp;
 
       bp_new->f1 |= SELECT;
 
       copy_v3_v3(bp_new->vec, location);
-      bp_new->vec[3] = 1.0f;
 
       BKE_nurb_knot_calc_u(nurb_new);
-
-      changed = true;
     }
+
+    BLI_addtail(&editnurb->nurbs, nurb_new);
+    changed = true;
   }
 
   return changed;