Revert "GPencil: Curvature support for length modifier."

Reason for revert: accidental push of a intermediate change locally.

This reverts commit 25e548c96b3d8c1698fd4385b4dc395665b5a7f6.

2 files changed, 39 insertions, 226 deletions

diff --git a/source/blender/blenkernel/BKE_gpencil_geom.h b/source/blender/blenkernel/BKE_gpencil_geom.h
index 20ee9199dba..d472fd6f02b 100644
--- a/source/blender/blenkernel/BKE_gpencil_geom.h
+++ b/source/blender/blenkernel/BKE_gpencil_geom.h
@@ -114,12 +114,7 @@ void BKE_gpencil_dissolve_points(struct bGPdata *gpd,
 bool BKE_gpencil_stroke_stretch(struct bGPDstroke *gps,
                                 const float dist,
                                 const float overshoot_fac,
-                                const short mode,
-                                const bool follow_curvature,
-                                const int extra_point_count,
-                                const float edge_point_tradeoff,
-                                const float max_angle,
-                                const bool invert_curvature);
+                                const short mode);
 bool BKE_gpencil_stroke_trim_points(struct bGPDstroke *gps,
                                     const int index_from,
                                     const int index_to);
diff --git a/source/blender/blenkernel/intern/gpencil_geom.cc b/source/blender/blenkernel/intern/gpencil_geom.cc
index 2d825705ab0..8ff026231f5 100644
--- a/source/blender/blenkernel/intern/gpencil_geom.cc
+++ b/source/blender/blenkernel/intern/gpencil_geom.cc
@@ -541,241 +541,64 @@ bool BKE_gpencil_stroke_sample(bGPdata *gpd, bGPDstroke *gps, const float dist,
 }
 
 /**
- * Give extra stroke points before and after the original tip points.
- * \param gps: Target stroke
- * \param count_before: how many extra points to be added before a stroke
- * \param count_after: how many extra points to be added after a stroke
- */
-static bool BKE_gpencil_stroke_extra_points(bGPDstroke *gps,
-                                            const int count_before,
-                                            const int count_after)
-{
-  bGPDspoint *pts = gps->points;
-
-  BLI_assert(count_before >= 0);
-  BLI_assert(count_after >= 0);
-  if (!count_before && !count_after) {
-    return false;
-  }
-
-  const int new_count = count_before + count_after + gps->totpoints;
-
-  bGPDspoint *new_pts = (bGPDspoint *)MEM_mallocN(sizeof(bGPDspoint) * new_count, __func__);
-
-  for (int i = 0; i < count_before; i++) {
-    memcpy(&new_pts[i], &pts[0], sizeof(bGPDspoint));
-  }
-  memcpy(&new_pts[count_before], pts, sizeof(bGPDspoint) * gps->totpoints);
-  for (int i = new_count - count_after; i < new_count; i++) {
-    memcpy(&new_pts[i], &pts[gps->totpoints - 1], sizeof(bGPDspoint));
-  }
-
-  if (gps->dvert) {
-    MDeformVert *new_dv = (MDeformVert *)MEM_mallocN(sizeof(MDeformVert) * new_count, __func__);
-
-    for (int i = 0; i < new_count; i++) {
-      MDeformVert *dv = &gps->dvert[CLAMPIS(i - count_before, 0, gps->totpoints - 1)];
-      int inew = i;
-      new_dv[inew].flag = dv->flag;
-      new_dv[inew].totweight = dv->totweight;
-      new_dv[inew].dw = (MDeformWeight *)MEM_mallocN(sizeof(MDeformWeight) * dv->totweight,
-                                                     __func__);
-      memcpy(new_dv[inew].dw, dv->dw, sizeof(MDeformWeight) * dv->totweight);
-    }
-    BKE_gpencil_free_stroke_weights(gps);
-    MEM_freeN(gps->dvert);
-    gps->dvert = new_dv;
-  }
-
-  MEM_freeN(gps->points);
-  gps->points = new_pts;
-  gps->totpoints = new_count;
-
-  return true;
-}
-
-/**
  * Backbone stretch similar to Freestyle.
  * \param gps: Stroke to sample.
- * \param dist: Length of the added section.
- * \param overshoot_fac: Relative length of the curve which is used to determine the extension.
+ * \param dist: Distance of one segment.
+ * \param overshoot_fac: How exact is the follow curve algorithm.
  * \param mode: Affect to Start, End or Both extremes (0->Both, 1->Start, 2->End)
- * \param follow_curvature: True for appproximating curvature of given overshoot.
- * \param extra_point_count: When follow_curvature is true, use this amount of extra points
  */
 bool BKE_gpencil_stroke_stretch(bGPDstroke *gps,
                                 const float dist,
                                 const float overshoot_fac,
-                                const short mode,
-                                const bool follow_curvature,
-                                const int extra_point_count,
-                                const float edge_point_tradeoff,
-                                const float max_angle,
-                                const bool invert_curvature)
+                                const short mode)
 {
 #define BOTH 0
 #define START 1
 #define END 2
 
-  const bool do_start = ELEM(mode, BOTH, START);
-  const bool do_end = ELEM(mode, BOTH, END);
-  float used_percent_length = overshoot_fac;
-  CLAMP(used_percent_length, 1e-4f, 1.0f);
-  if (!isfinite(used_percent_length)) {
-    /* If gps->totpoints == 2, then #overshoot_fac is allowed to be non finite. */
-    used_percent_length = 0.1f;
-  }
+  bGPDspoint *pt = gps->points, *last_pt, *second_last, *next_pt;
+  int i;
+  float threshold = (overshoot_fac == 0 ? 0.001f : overshoot_fac);
 
-  if (gps->totpoints <= 1 || dist < FLT_EPSILON || extra_point_count <= 0) {
+  if (gps->totpoints < 2 || dist < FLT_EPSILON) {
     return false;
   }
 
-  /* NOTE: When it's just a straight line, we don't need to do the curvature stuff. */
-  if (!follow_curvature || gps->totpoints <= 2) {
-    /* Not following curvature, just straight line. */
-    /* NOTE: #overshoot_point_param can not be zero. */
-    float overshoot_point_param = used_percent_length * (gps->totpoints - 1);
-    float result[3];
-
-    if (do_start) {
-      int index1 = floor(overshoot_point_param);
-      int index2 = ceil(overshoot_point_param);
-      interp_v3_v3v3(result,
-                     &gps->points[index1].x,
-                     &gps->points[index2].x,
-                     fmodf(overshoot_point_param, 1.0f));
-      sub_v3_v3(result, &gps->points[0].x);
-      if (UNLIKELY(is_zero_v3(result))) {
-        sub_v3_v3v3(result, &gps->points[1].x, &gps->points[0].x);
-      }
-      madd_v3_v3fl(&gps->points[0].x, result, -dist / len_v3(result));
-    }
-
-    if (do_end) {
-      int index1 = gps->totpoints - 1 - floor(overshoot_point_param);
-      int index2 = gps->totpoints - 1 - ceil(overshoot_point_param);
-      interp_v3_v3v3(result,
-                     &gps->points[index1].x,
-                     &gps->points[index2].x,
-                     fmodf(overshoot_point_param, 1.0f));
-      sub_v3_v3(result, &gps->points[gps->totpoints - 1].x);
-      if (UNLIKELY(is_zero_v3(result))) {
-        sub_v3_v3v3(
-            result, &gps->points[gps->totpoints - 2].x, &gps->points[gps->totpoints - 1].x);
-      }
-      madd_v3_v3fl(&gps->points[gps->totpoints - 1].x, result, -dist / len_v3(result));
-    }
-    return true;
-  }
-
-  /* Curvature calculation. */
-
-  /* First allocate the new stroke size. */
-  const int first_old_index = do_start ? extra_point_count : 0;
-  const int last_old_index = gps->totpoints - 1 + first_old_index;
-  const int orig_totpoints = gps->totpoints;
-  BKE_gpencil_stroke_extra_points(gps, first_old_index, do_end ? extra_point_count : 0);
-
-  /* The overshoot length in terms of angles with at least 1 used angle. */
-  const float overshoot_parameter = used_percent_length * (orig_totpoints - 2);
-  int overshoot_pointcount = ceil(overshoot_parameter);
-  CLAMP(overshoot_pointcount, 1, orig_totpoints - 2);
-
-  float point_edge_tradeoff = 1.0f - edge_point_tradeoff;
-
-  /* Do for both sides without code duplication. */
-  float no[3], vec1[3], vec2[3], total_angle[3];
-  for (int k = 0; k < 2; k++) {
-    if ((k == 0 && !do_start) || (k == 1 && !do_end)) {
-      continue;
-    }
-
-    const int start_i = k == 0 ? first_old_index :
-                                 last_old_index;  // first_old_index, last_old_index
-    const int dir_i = 1 - k * 2;                  // 1, -1
-
-    sub_v3_v3v3(vec1, &gps->points[start_i + dir_i].x, &gps->points[start_i].x);
-    zero_v3(total_angle);
-    float segment_length = normalize_v3(vec1);
-    float overshoot_length = 0.0f;
-
-    /* Accumulate rotation angle and length. */
-    int j = 0;
-    for (int i = start_i; j < overshoot_pointcount; i += dir_i, j++) {
-      /* Don't fully add last segment to get continuity in overshoot_fac. */
-      float fac = fmin(overshoot_parameter - j, 1.0f);
-
-      /* Read segments. */
-      copy_v3_v3(vec2, vec1);
-      sub_v3_v3v3(vec1, &gps->points[i + dir_i * 2].x, &gps->points[i + dir_i].x);
-      const float len = normalize_v3(vec1);
-      float angle = angle_normalized_v3v3(vec1, vec2) * fac;
-
-      /* Add half of both adjacent legs of the current angle. */
-      const float added_len = (segment_length + len) * 0.5f * fac;
-      overshoot_length += added_len;
-      segment_length = len;
-
-      if (angle > max_angle) {
-        continue;
-      }
-      if (angle > M_PI * 0.995f) {
-        continue;
-      }
-
-      angle *= powf(added_len, point_edge_tradeoff);
-
-      cross_v3_v3v3(no, vec1, vec2);
-      normalize_v3_length(no, angle);
-      add_v3_v3(total_angle, no);
+  last_pt = &pt[gps->totpoints - 1];
+  second_last = &pt[gps->totpoints - 2];
+  next_pt = &pt[1];
+
+  if (mode == BOTH || mode == START) {
+    float len1 = 0.0f;
+    i = 1;
+    while (len1 < threshold && gps->totpoints > i) {
+      next_pt = &pt[i];
+      len1 = len_v3v3(&next_pt->x, &pt->x);
+      i++;
     }
+    float extend1 = (len1 + dist) / len1;
+    float result1[3];
 
-    if (UNLIKELY(overshoot_length == 0.0f)) {
-      /* Don't do a proper extension if the used points are all in the same position. */
-      continue;
-    }
+    interp_v3_v3v3(result1, &next_pt->x, &pt->x, extend1);
+    copy_v3_v3(&pt->x, result1);
+  }
 
-    sub_v3_v3v3(vec1, &gps->points[start_i].x, &gps->points[start_i + dir_i].x);
-    /* In general curvature = 1/radius. For the curvature without the
-     * weights introduced point_edge_tradeoff the calculation is
-     * curvature = delta angle/delta arclength = len_v3(total_angle) / overshoot_length */
-    float curvature = normalize_v3(total_angle) / overshoot_length;
-    /* Compensate for the weights powf(added_len, point_edge_tradeoff). */
-    curvature /= powf(overshoot_length / fminf(overshoot_parameter, (float)j),
-                      point_edge_tradeoff);
-    if (invert_curvature) {
-      curvature = -curvature;
-    }
-    const float angle_step = curvature * dist / extra_point_count;
-    float step_length = dist / extra_point_count;
-    if (fabsf(angle_step) > FLT_EPSILON) {
-      /* Make a direct step length from the assigned arc step length. */
-      step_length *= sin(angle_step * 0.5f) / (angle_step * 0.5f);
-    }
-    else {
-      zero_v3(total_angle);
+  if (mode == BOTH || mode == END) {
+    float len2 = 0.0f;
+    i = 2;
+    while (len2 < threshold && gps->totpoints >= i) {
+      second_last = &pt[gps->totpoints - i];
+      len2 = len_v3v3(&last_pt->x, &second_last->x);
+      i++;
     }
-    const float prev_length = normalize_v3_length(vec1, step_length);
-
-    /* Build rotation matrix here to get best performance. */
-    float rot[3][3];
-    float q[4];
-    axis_angle_to_quat(q, total_angle, angle_step);
-    quat_to_mat3(rot, q);
 
-    /* Rotate the starting direction to account for change in edge lengths. */
-    axis_angle_to_quat(q,
-                       total_angle,
-                       fmaxf(0.0f, 1.0f - fabs(point_edge_tradeoff)) *
-                           (curvature * prev_length - angle_step) / 2.0f);
-    mul_qt_v3(q, vec1);
+    float extend2 = (len2 + dist) / len2;
+    float result2[3];
+    interp_v3_v3v3(result2, &second_last->x, &last_pt->x, extend2);
 
-    /* Now iteratively accumulate the segments with a rotating added direction. */
-    for (int i = start_i - dir_i, j = 0; j < extra_point_count; i -= dir_i, j++) {
-      mul_v3_m3v3(vec1, rot, vec1);
-      add_v3_v3v3(&gps->points[i].x, vec1, &gps->points[i + dir_i].x);
-    }
+    copy_v3_v3(&last_pt->x, result2);
   }
+
   return true;
 }
 
@@ -926,7 +749,6 @@ bool BKE_gpencil_stroke_shrink(bGPDstroke *gps, const float dist, const short mo
 
   second_last = &pt[gps->totpoints - 2];
 
-  float len;
   float len1, cut_len1;
   float len2, cut_len2;
   len1 = len2 = cut_len1 = cut_len2 = 0.0f;
@@ -937,13 +759,11 @@ bool BKE_gpencil_stroke_shrink(bGPDstroke *gps, const float dist, const short mo
     i = 0;
     index_end = gps->totpoints - 1;
     while (len1 < dist && gps->totpoints > i + 1) {
-      len = len_v3v3(&pt[i].x, &pt[i + 1].x);
-      len1 += len;
+      len1 += len_v3v3(&pt[i].x, &pt[i + 1].x);
       cut_len1 = len1 - dist;
       i++;
     }
     index_start = i - 1;
-    interp_v3_v3v3(&pt[index_start].x, &pt[index_start + 1].x, &pt[index_start].x, cut_len1 / len);
   }
 
   if (mode == END) {
@@ -951,20 +771,18 @@ bool BKE_gpencil_stroke_shrink(bGPDstroke *gps, const float dist, const short mo
     i = 2;
     while (len2 < dist && gps->totpoints >= i) {
       second_last = &pt[gps->totpoints - i];
-      len = len_v3v3(&second_last[1].x, &second_last->x);
-      len2 += len;
+      len2 += len_v3v3(&second_last[1].x, &second_last->x);
       cut_len2 = len2 - dist;
       i++;
     }
     index_end = gps->totpoints - i + 2;
-    interp_v3_v3v3(&pt[index_end].x, &pt[index_end - 1].x, &pt[index_end].x, cut_len2 / len);
   }
 
   if (index_end <= index_start) {
     index_start = index_end = 0; /* empty stroke */
   }
 
-  if ((index_end == index_start + 1) && (cut_len1 + cut_len2 < 0)) {
+  if ((index_end == index_start + 1) && (cut_len1 + cut_len2 < dist)) {
     index_start = index_end = 0; /* no length left to cut */
   }