real fix for [#35097], (curve cap flipping).

previous commit was incorrect, the face flipping depended on the orientation of the curve.

fix by passing the bevel direction to the fill function so we can have a reliable front/back.

This also gives some speedup for all curve filling since we can avoid calculating the normal since its already known.

1 files changed, 26 insertions, 11 deletions

diff --git a/source/blender/blenkernel/intern/displist.c b/source/blender/blenkernel/intern/displist.c
index 12c9ec3a52a..9033d9a0824 100644
--- a/source/blender/blenkernel/intern/displist.c
+++ b/source/blender/blenkernel/intern/displist.c
@@ -444,8 +444,12 @@ static void curve_to_displist(Curve *cu, ListBase *nubase, ListBase *dispbase, i
 	}
 }
 
-
-void BKE_displist_fill(ListBase *dispbase, ListBase *to, int flipnormal)
+/**
+ * \param normal_proj  Optional normal thats used to project the scanfill verts into 2d coords.
+ * Pass this along if known since it saves time calculating the normal.
+ * \param flipnormal  Flip the normal (same as passing \a normal_proj negated)
+ */
+void BKE_displist_fill(ListBase *dispbase, ListBase *to, const float normal_proj[3], const bool flipnormal)
 {
 	ScanFillContext sf_ctx;
 	ScanFillVert *sf_vert, *sf_vert_new, *sf_vert_last;
@@ -508,7 +512,10 @@ void BKE_displist_fill(ListBase *dispbase, ListBase *to, int flipnormal)
 		}
 
 		/* XXX (obedit && obedit->actcol) ? (obedit->actcol-1) : 0)) { */
-		if (totvert && (tot = BLI_scanfill_calc(&sf_ctx, BLI_SCANFILL_CALC_REMOVE_DOUBLES | BLI_SCANFILL_CALC_HOLES))) {
+		if (totvert && (tot = BLI_scanfill_calc_ex(&sf_ctx,
+		                                           BLI_SCANFILL_CALC_REMOVE_DOUBLES | BLI_SCANFILL_CALC_HOLES,
+		                                           normal_proj)))
+		{
 			if (tot) {
 				dlnew = MEM_callocN(sizeof(DispList), "filldisplist");
 				dlnew->type = DL_INDEX3;
@@ -568,6 +575,7 @@ void BKE_displist_fill(ListBase *dispbase, ListBase *to, int flipnormal)
 
 static void bevels_to_filledpoly(Curve *cu, ListBase *dispbase)
 {
+	const float z_up[3] = {0.0f, 0.0f, 1.0f};
 	ListBase front, back;
 	DispList *dl, *dlnew;
 	float *fp, *fp1;
@@ -624,13 +632,13 @@ static void bevels_to_filledpoly(Curve *cu, ListBase *dispbase)
 		dl = dl->next;
 	}
 
-	BKE_displist_fill(&front, dispbase, 1);
-	BKE_displist_fill(&back, dispbase, 0);
+	BKE_displist_fill(&front, dispbase, z_up, true);
+	BKE_displist_fill(&back, dispbase, z_up, false);
 
 	BKE_displist_free(&front);
 	BKE_displist_free(&back);
 
-	BKE_displist_fill(dispbase, dispbase, 0);
+	BKE_displist_fill(dispbase, dispbase, z_up, false);
 }
 
 static void curve_to_filledpoly(Curve *cu, ListBase *UNUSED(nurb), ListBase *dispbase)
@@ -642,7 +650,8 @@ static void curve_to_filledpoly(Curve *cu, ListBase *UNUSED(nurb), ListBase *dis
 		bevels_to_filledpoly(cu, dispbase);
 	}
 	else {
-		BKE_displist_fill(dispbase, dispbase, 0);
+		/* TODO, investigate passing zup instead of NULL */
+		BKE_displist_fill(dispbase, dispbase, NULL,0);
 	}
 }
 
@@ -1436,6 +1445,8 @@ static void do_makeDispListCurveTypes(Scene *scene, Object *ob, ListBase *dispba
 						DispList *dlb;
 						ListBase bottom_capbase = {NULL, NULL};
 						ListBase top_capbase = {NULL, NULL};
+						float bottom_no[3] = {0.0f};
+						float top_no[3] = {0.0f};
 
 						for (dlb = dlbev.first; dlb; dlb = dlb->next) {
 							const float bevfac1 = min_ff(cu->bevfac1, cu->bevfac2);
@@ -1527,10 +1538,14 @@ static void do_makeDispListCurveTypes(Scene *scene, Object *ob, ListBase *dispba
 									rotateBevelPiece(cu, bevp, NULL, dlb, 0.0f, widfac, fac, &data);
 
 								if (cu->bevobj && (cu->flag & CU_FILL_CAPS) && !(nu->flagu & CU_NURB_CYCLIC)) {
-									if (a == 1)
+									if (a == 1) {
 										fillBevelCap(nu, dlb, cur_data - 3 * dlb->nr, &bottom_capbase);
-									if (a == steps - 1)
+										negate_v3_v3(bottom_no, bevp->dir);
+									}
+									if (a == steps - 1) {
 										fillBevelCap(nu, dlb, cur_data, &top_capbase);
+										copy_v3_v3(top_no, bevp->dir);
+									}
 								}
 							}
 
@@ -1539,8 +1554,8 @@ static void do_makeDispListCurveTypes(Scene *scene, Object *ob, ListBase *dispba
 						}
 
 						if (bottom_capbase.first) {
-							BKE_displist_fill(&bottom_capbase, dispbase, false);
-							BKE_displist_fill(&top_capbase, dispbase, true);
+							BKE_displist_fill(&bottom_capbase, dispbase, bottom_no, false);
+							BKE_displist_fill(&top_capbase, dispbase, top_no, false);
 							BKE_displist_free(&bottom_capbase);
 							BKE_displist_free(&top_capbase);
 						}