Fix T71200: Build curve geometry in one piece

Currently a curve's beveled geometry is built with duplicate geometry
along the seams between the "front," "back," etc, sections of the
curve. This builds them in one piece, resulting in smooth geometry.

Other than the duplicate geometry, the vertex positions are the same
as before.

Reviewed By: campbellbarton, mano-wii

Differential Revision: https://developer.blender.org/D6562

1 files changed, 67 insertions, 70 deletions

diff --git a/source/blender/blenkernel/intern/curve.c b/source/blender/blenkernel/intern/curve.c
index 12bb7b573bd..4f0ff8bdcd3 100644
--- a/source/blender/blenkernel/intern/curve.c
+++ b/source/blender/blenkernel/intern/curve.c
@@ -1805,91 +1805,88 @@ void BKE_curve_bevel_make(Object *ob, ListBase *disp)
     }
   }
   else {
-    short dnr;
-
-    /* bevel now in three parts, for proper vertex normals */
-    /* part 1, back */
-
-    if ((cu->flag & CU_BACK) || !(cu->flag & CU_FRONT)) {
-      dnr = nr = 2 + cu->bevresol;
-      if ((cu->flag & (CU_FRONT | CU_BACK)) == 0) {
-        nr = 3 + 2 * cu->bevresol;
-      }
-      dl = MEM_callocN(sizeof(DispList), "makebevelcurve p1");
-      dl->verts = MEM_malloc_arrayN(nr, sizeof(float[3]), "makebevelcurve p1");
-      BLI_addtail(disp, dl);
-      dl->type = DL_SEGM;
-      dl->parts = 1;
-      dl->flag = DL_BACK_CURVE;
-      dl->nr = nr;
-
-      /* half a circle */
-      fp = dl->verts;
-      dangle = ((float)M_PI_2 / (dnr - 1));
-      angle = -(nr - 1) * dangle;
-
-      for (a = 0; a < nr; a++) {
+    /* The general case for nonzero extrusion or an incomplete loop. */
+    dl = MEM_callocN(sizeof(DispList), "makebevelcurve");
+    if ((cu->flag & (CU_FRONT | CU_BACK)) == 0) {
+      /* The full loop. */
+      nr = 4 * cu->bevresol + 6;
+      dl->flag = DL_FRONT_CURVE | DL_BACK_CURVE;
+    }
+    else if ((cu->flag & CU_FRONT) && (cu->flag & CU_BACK)) {
+      /* Half the loop. */
+      nr = 2 * (cu->bevresol + 1) + ((cu->ext1 == 0.0f) ? 1 : 2);
+      dl->flag = DL_FRONT_CURVE | DL_BACK_CURVE;
+    }
+    else {
+      /* One quarter of the loop (just front or back). */
+      nr = (cu->ext1 == 0.0f) ? cu->bevresol + 2 : cu->bevresol + 3;
+      dl->flag = (cu->flag & CU_FRONT) ? DL_FRONT_CURVE : DL_BACK_CURVE;
+    }
+
+    dl->verts = MEM_malloc_arrayN(nr, sizeof(float[3]), "makebevelcurve");
+    BLI_addtail(disp, dl);
+    /* Use a different type depending on whether the loop is complete or not. */
+    dl->type = ((cu->flag & (CU_FRONT | CU_BACK)) == 0) ? DL_POLY : DL_SEGM;
+    dl->parts = 1;
+    dl->nr = nr;
+
+    fp = dl->verts;
+    dangle = (float)M_PI_2 / (cu->bevresol + 1);
+    angle = 0.0;
+
+    /* Build the back section. */
+    if (cu->flag & CU_BACK || !(cu->flag & CU_FRONT)) {
+      angle = (float)M_PI_2 * 3.0f;
+      for (a = 0; a < cu->bevresol + 2; a++) {
         fp[0] = 0.0;
         fp[1] = (float)(cosf(angle) * (cu->ext2));
         fp[2] = (float)(sinf(angle) * (cu->ext2)) - cu->ext1;
         angle += dangle;
         fp += 3;
       }
+      if ((cu->ext1 != 0.0f) && !(cu->flag & CU_FRONT) && (cu->flag & CU_BACK)) {
+        /* Add the extrusion if we're only building the back. */
+        fp[0] = 0.0;
+        fp[1] = cu->ext2;
+        fp[2] = cu->ext1;
+      }
     }
 
-    /* part 2, sidefaces */
-    if (cu->ext1 != 0.0f) {
-      nr = 2;
-
-      dl = MEM_callocN(sizeof(DispList), "makebevelcurve p2");
-      dl->verts = MEM_malloc_arrayN(nr, sizeof(float[3]), "makebevelcurve p2");
-      BLI_addtail(disp, dl);
-      dl->type = DL_SEGM;
-      dl->parts = 1;
-      dl->nr = nr;
-
-      fp = dl->verts;
-      fp[1] = cu->ext2;
-      fp[2] = -cu->ext1;
-      fp[4] = cu->ext2;
-      fp[5] = cu->ext1;
-
-      if ((cu->flag & (CU_FRONT | CU_BACK)) == 0) {
-        dl = MEM_dupallocN(dl);
-        dl->verts = MEM_dupallocN(dl->verts);
-        BLI_addtail(disp, dl);
-
-        fp = dl->verts;
-        fp[1] = -fp[1];
-        fp[2] = -fp[2];
-        fp[4] = -fp[4];
-        fp[5] = -fp[5];
+    /* Build the front section. */
+    if (cu->flag & CU_FRONT || !(cu->flag & CU_BACK)) {
+      if ((cu->ext1 != 0.0f) && !(cu->flag & CU_BACK) && (cu->flag & CU_FRONT)) {
+        /* Add the extrusion if we're only building the back. */
+        fp[0] = 0.0;
+        fp[1] = cu->ext2;
+        fp[2] = -cu->ext1;
+        fp += 3;
+      }
+      /* Don't duplicate the last back vertex. */
+      angle = (cu->ext1 == 0.0f && (cu->flag & CU_BACK)) ? dangle : 0;
+      for (a = 0; a < cu->bevresol + 2; a++) {
+        fp[0] = 0.0;
+        fp[1] = (float)(cosf(angle) * (cu->ext2));
+        fp[2] = (float)(sinf(angle) * (cu->ext2)) + cu->ext1;
+        angle += dangle;
+        fp += 3;
       }
     }
 
-    /* part 3, front */
-    if ((cu->flag & CU_FRONT) || !(cu->flag & CU_BACK)) {
-      dnr = nr = 2 + cu->bevresol;
-      if ((cu->flag & (CU_FRONT | CU_BACK)) == 0) {
-        nr = 3 + 2 * cu->bevresol;
+    /* Build the other half only if we're building the full loop. */
+    if (!(cu->flag & (CU_FRONT | CU_BACK))) {
+      for (a = 0; a < cu->bevresol + 1; a++) {
+        fp[0] = 0.0;
+        fp[1] = (float)(cosf(angle) * (cu->ext2));
+        fp[2] = (float)(sinf(angle) * (cu->ext2)) + cu->ext1;
+        angle += dangle;
+        fp += 3;
       }
-      dl = MEM_callocN(sizeof(DispList), "makebevelcurve p3");
-      dl->verts = MEM_malloc_arrayN(nr, sizeof(float[3]), "makebevelcurve p3");
-      BLI_addtail(disp, dl);
-      dl->type = DL_SEGM;
-      dl->flag = DL_FRONT_CURVE;
-      dl->parts = 1;
-      dl->nr = nr;
-
-      /* half a circle */
-      fp = dl->verts;
-      angle = 0.0;
-      dangle = ((float)M_PI_2 / (dnr - 1));
 
-      for (a = 0; a < nr; a++) {
+      angle = (float)M_PI;
+      for (a = 0; a < cu->bevresol + 1; a++) {
         fp[0] = 0.0;
         fp[1] = (float)(cosf(angle) * (cu->ext2));
-        fp[2] = (float)(sinf(angle) * (cu->ext2)) + cu->ext1;
+        fp[2] = (float)(sinf(angle) * (cu->ext2)) - cu->ext1;
         angle += dangle;
         fp += 3;
       }