Curves: Add custom profile bevel support

This adds support for the same custom bevel profile widget used in
the bevel tool and modifier to the geometry generation for curves.

This is expecially useful for text and 2D curves with extrusion, as
it works much better than a weld & bevel modifier combination.
It can also be useful for adding quick detail to pipe-like objects.

The curve holds the CurveProfile struct and a new "Bevel Mode"
property decides which type of bevel to build, round, object, or
custom profile.

Although curves can already use another curve to make the bevel
geometry, this is a quicker way, and it also defines the profile of
just one corner of the bevel, so it isn't redundant. It's also nice
to have the same custom profile functionality wherever there is bevel.

Differential Revision: https://developer.blender.org/D8402

1 files changed, 102 insertions, 54 deletions

diff --git a/source/blender/blenkernel/intern/curve_bevel.c b/source/blender/blenkernel/intern/curve_bevel.c
index edf5b82f822..911a98cb607 100644
--- a/source/blender/blenkernel/intern/curve_bevel.c
+++ b/source/blender/blenkernel/intern/curve_bevel.c
@@ -23,15 +23,18 @@
 
 #include <string.h>
 
+#include "BLI_alloca.h"
 #include "BLI_listbase.h"
 #include "BLI_math_base.h"
 
 #include "MEM_guardedalloc.h"
 
 #include "DNA_curve_types.h"
+#include "DNA_curveprofile_types.h"
 #include "DNA_object_types.h"
 
 #include "BKE_curve.h"
+#include "BKE_curveprofile.h"
 #include "BKE_displist.h"
 
 typedef enum CurveBevelFillType {
@@ -53,6 +56,33 @@ static CurveBevelFillType curve_bevel_get_fill_type(const Curve *curve)
   return (curve->flag & CU_FRONT) ? FRONT : BACK;
 }
 
+static void bevel_quarter_fill(Curve *curve, float *quarter_coords_x, float *quarter_coords_y)
+{
+  if (curve->bevel_mode == CU_BEV_MODE_ROUND) {
+    float angle = 0.0f;
+    const float dangle = (float)M_PI_2 / (curve->bevresol + 1);
+    for (int i = 0; i < curve->bevresol + 1; i++) {
+      quarter_coords_x[i] = (float)(cosf(angle) * (curve->ext2));
+      quarter_coords_y[i] = (float)(sinf(angle) * (curve->ext2));
+      angle += dangle;
+    }
+  }
+  else {
+    /* The curve profile evaluation should be done when the resolution is set. */
+    BLI_assert(curve->bevel_profile->segments != NULL);
+    BLI_assert(curve->bevel_profile->segments_len == curve->bevresol + 1);
+
+    /* If there aren't enough samples, the curveprofile won't
+     * sample the start vertex, so set it manually instead. */
+    quarter_coords_x[0] = curve->ext2;
+    quarter_coords_y[0] = 0.0f;
+    for (int i = 1; i < curve->bevresol + 1; i++) {
+      quarter_coords_x[i] = (float)(curve->bevel_profile->segments[i].x * (curve->ext2));
+      quarter_coords_y[i] = (float)(curve->bevel_profile->segments[i].y * (curve->ext2));
+    }
+  }
+}
+
 static void curve_bevel_make_extrude_and_fill(Curve *cu,
                                               ListBase *disp,
                                               const bool use_extrude,
@@ -60,10 +90,20 @@ static void curve_bevel_make_extrude_and_fill(Curve *cu,
 {
   DispList *dl = MEM_callocN(sizeof(DispList), __func__);
 
+  /* Calculate the profile of the bevel once to reuse it for each quarter. We will need
+   * to flip around the indices for every other section in order to build around the circle
+   * in a consistent direction.
+   *
+   * These should be small enough for stack allocations because the current limit
+   * for #Curve.bevresol is 32.  */
+  float *quarter_coords_x = alloca(sizeof(float) * (cu->bevresol + 1));
+  float *quarter_coords_y = alloca(sizeof(float) * (cu->bevresol + 1));
+  bevel_quarter_fill(cu, quarter_coords_x, quarter_coords_y);
+
   int nr;
   if (fill_type == FULL) {
     /* The full loop. */
-    nr = 4 * cu->bevresol + 6;
+    nr = 4 * cu->bevresol + (use_extrude ? 6 : 4);
     dl->flag = DL_FRONT_CURVE | DL_BACK_CURVE;
   }
   else if (fill_type == HALF) {
@@ -85,65 +125,69 @@ static void curve_bevel_make_extrude_and_fill(Curve *cu,
   dl->nr = nr;
 
   float *fp = dl->verts;
-  const float dangle = (float)M_PI_2 / (cu->bevresol + 1);
-  float angle = 0.0f;
 
   /* Build the back section. */
   if (ELEM(fill_type, BACK, HALF, FULL)) {
-    angle = (float)M_PI_2 * 3.0f;
-    for (int i = 0; i < cu->bevresol + 2; i++) {
+    /* Add the bottom vertex. */
+    fp[0] = 0.0f;
+    fp[1] = 0.0f;
+    fp[2] = -cu->ext1 - cu->ext2;
+    fp += 3;
+
+    for (int i = cu->bevresol; i >= 0; i--) {
       fp[0] = 0.0f;
-      fp[1] = (float)(cosf(angle) * (cu->ext2));
-      fp[2] = (float)(sinf(angle) * (cu->ext2)) - cu->ext1;
-      angle += dangle;
+      fp[1] = quarter_coords_x[i];
+      fp[2] = -quarter_coords_y[i] - cu->ext1;
       fp += 3;
     }
-    if (use_extrude && fill_type == BACK) {
-      /* Add the extrusion if we're only building the back. */
-      fp[0] = 0.0f;
-      fp[1] = cu->ext2;
-      fp[2] = cu->ext1;
-    }
+  }
+
+  /* Add the extrusion if we're only building either the back or the front. */
+  if (use_extrude && ELEM(fill_type, FRONT, BACK)) {
+    fp[0] = 0.0f;
+    fp[1] = cu->ext2;
+    fp[2] = (fill_type == FRONT) ? -cu->ext1 : cu->ext1;
+    fp += 3;
   }
 
   /* Build the front section. */
   if (ELEM(fill_type, FRONT, HALF, FULL)) {
-    if (use_extrude && fill_type == FRONT) {
-      /* Add the extrusion if we're only building the front. */
-      fp[0] = 0.0f;
-      fp[1] = cu->ext2;
-      fp[2] = -cu->ext1;
-      fp += 3;
-    }
     /* Don't duplicate the last back vertex. */
-    angle = (!use_extrude && ELEM(fill_type, HALF, FULL)) ? dangle : 0;
-    int front_len = (!use_extrude && ELEM(fill_type, HALF, FULL)) ? cu->bevresol + 1 :
-                                                                    cu->bevresol + 2;
-    for (int i = 0; i < front_len; i++) {
+    const int front_start = (!use_extrude && ELEM(fill_type, HALF, FULL)) ? 1 : 0;
+    for (int i = front_start; i < cu->bevresol + 1; i++) {
       fp[0] = 0.0f;
-      fp[1] = (float)(cosf(angle) * (cu->ext2));
-      fp[2] = (float)(sinf(angle) * (cu->ext2)) + cu->ext1;
-      angle += dangle;
+      fp[1] = quarter_coords_x[i];
+      fp[2] = quarter_coords_y[i] + cu->ext1;
       fp += 3;
     }
+    /* Add the top vertex. */
+    fp[0] = 0.0f;
+    fp[1] = 0.0f;
+    fp[2] = cu->ext1 + cu->ext2;
+    fp += 3;
   }
 
   /* Build the other half only if we're building the full loop. */
   if (fill_type == FULL) {
-    for (int i = 0; i < cu->bevresol + 1; i++) {
+    for (int i = cu->bevresol; i > 0; i--) {
       fp[0] = 0.0f;
-      fp[1] = (float)(cosf(angle) * (cu->ext2));
-      fp[2] = (float)(sinf(angle) * (cu->ext2)) + cu->ext1;
-      angle += dangle;
+      fp[1] = -quarter_coords_x[i];
+      fp[2] = quarter_coords_y[i] + cu->ext1;
+      fp += 3;
+    }
+
+    if (use_extrude) {
+      /* Add the extrusion. */
+      fp[0] = 0.0f;
+      fp[1] = -cu->ext2;
+      fp[2] = cu->ext1;
       fp += 3;
     }
 
-    angle = (float)M_PI;
     for (int i = 0; i < cu->bevresol + 1; i++) {
       fp[0] = 0.0f;
-      fp[1] = (float)(cosf(angle) * (cu->ext2));
-      fp[2] = (float)(sinf(angle) * (cu->ext2)) - cu->ext1;
-      angle += dangle;
+      fp[1] = -quarter_coords_x[i];
+      fp[2] = -quarter_coords_y[i] - cu->ext1;
       fp += 3;
     }
   }
@@ -193,6 +237,9 @@ static void curve_bevel_make_only_extrude(Curve *cu, ListBase *disp)
 
 static void curve_bevel_make_from_object(Curve *cu, ListBase *disp)
 {
+  if (cu->bevobj == NULL) {
+    return;
+  }
   if (cu->bevobj->type != OB_CURVE) {
     return;
   }
@@ -244,29 +291,30 @@ void BKE_curve_bevel_make(Object *ob, ListBase *disp)
 {
   Curve *curve = ob->data;
 
-  const bool use_extrude = curve->ext1 != 0.0f;
-  const bool use_bevel = curve->ext2 != 0.0f;
-
   BLI_listbase_clear(disp);
 
-  if (curve->bevobj) {
-    curve_bevel_make_from_object(curve, disp);
-  }
-  else if (!(use_extrude || use_bevel)) {
-    /* Pass. */
-  }
-  else if (use_extrude && !use_bevel) {
-    curve_bevel_make_only_extrude(curve, disp);
+  if (curve->bevel_mode == CU_BEV_MODE_OBJECT) {
+    if (curve->bevobj != NULL) {
+      curve_bevel_make_from_object(curve, disp);
+    }
   }
   else {
-    CurveBevelFillType fill_type = curve_bevel_get_fill_type(curve);
-
-    if (!use_extrude && fill_type == FULL) {
-      curve_bevel_make_full_circle(curve, disp);
+    const bool use_extrude = curve->ext1 != 0.0f;
+    const bool use_bevel = curve->ext2 != 0.0f;
+    /* Pass. */
+    if (use_extrude && !use_bevel) {
+      curve_bevel_make_only_extrude(curve, disp);
     }
-    else {
-      /* The general case for nonzero extrusion or an incomplete loop. */
-      curve_bevel_make_extrude_and_fill(curve, disp, use_extrude, fill_type);
+    else if (use_extrude || use_bevel) {
+      CurveBevelFillType fill_type = curve_bevel_get_fill_type(curve);
+
+      if (!use_extrude && fill_type == FULL && curve->bevel_mode == CU_BEV_MODE_ROUND) {
+        curve_bevel_make_full_circle(curve, disp);
+      }
+      else {
+        /* The general case for nonzero extrusion or an incomplete loop. */
+        curve_bevel_make_extrude_and_fill(curve, disp, use_extrude, fill_type);
+      }
     }
   }
 }