[Bf-blender-cvs] [a50a51eef00] master: Fix T88769: GPencil smooth incorrect behavior in cyclic strokes

[Antonio Vazquez]

Commit: a50a51eef00a4a8e756bf5846d64fd863dedcae6
Author: Antonio Vazquez
Date:   Wed Jun 23 17:26:20 2021 +0200
Branches: master
https://developer.blender.org/rBa50a51eef00a4a8e756bf5846d64fd863dedcae6

Fix T88769: GPencil smooth incorrect behavior in cyclic strokes

When use smooth tool in a cyclic stroke, the smoothing algorithm was not using the adjacent points if these are the end or start of stroke.

Now, the smooth uses the other extreme of the stroke to compute smoothness.

===================================================================

M	source/blender/blenkernel/intern/gpencil_geom.c

===================================================================

diff --git a/source/blender/blenkernel/intern/gpencil_geom.c b/source/blender/blenkernel/intern/gpencil_geom.c
index 982fc2abd65..36b8b5e52f0 100644
--- a/source/blender/blenkernel/intern/gpencil_geom.c
+++ b/source/blender/blenkernel/intern/gpencil_geom.c
@@ -793,6 +793,7 @@ bool BKE_gpencil_stroke_smooth(bGPDstroke *gps, int i, float inf)
 {
   bGPDspoint *pt = &gps->points[i];
   float sco[3] = {0.0f};
+  const bool is_cyclic = (gps->flag & GP_STROKE_CYCLIC) != 0;
 
   /* Do nothing if not enough points to smooth out */
   if (gps->totpoints <= 2) {
@@ -802,7 +803,7 @@ bool BKE_gpencil_stroke_smooth(bGPDstroke *gps, int i, float inf)
   /* Only affect endpoints by a fraction of the normal strength,
    * to prevent the stroke from shrinking too much
    */
-  if (ELEM(i, 0, gps->totpoints - 1)) {
+  if (!is_cyclic && ELEM(i, 0, gps->totpoints - 1)) {
     inf *= 0.1f;
   }
 
@@ -828,8 +829,22 @@ bool BKE_gpencil_stroke_smooth(bGPDstroke *gps, int i, float inf)
       int before = i - step;
       int after = i + step;
 
-      CLAMP_MIN(before, 0);
-      CLAMP_MAX(after, gps->totpoints - 1);
+      if (is_cyclic) {
+        if (before < 0) {
+          /* Sub to end point (before is already negative). */
+          before = gps->totpoints + before;
+          CLAMP(before, 0, gps->totpoints - 1);
+        }
+        if (after > gps->totpoints - 1) {
+          /* Add to start point. */
+          after = after - gps->totpoints;
+          CLAMP(after, 0, gps->totpoints - 1);
+        }
+      }
+      else {
+        CLAMP_MIN(before, 0);
+        CLAMP_MAX(after, gps->totpoints - 1);
+      }
 
       pt1 = &gps->points[before];
       pt2 = &gps->points[after];
@@ -855,6 +870,7 @@ bool BKE_gpencil_stroke_smooth(bGPDstroke *gps, int i, float inf)
 bool BKE_gpencil_stroke_smooth_strength(bGPDstroke *gps, int point_index, float influence)
 {
   bGPDspoint *ptb = &gps->points[point_index];
+  const bool is_cyclic = (gps->flag & GP_STROKE_CYCLIC) != 0;
 
   /* Do nothing if not enough points */
   if ((gps->totpoints <= 2) || (point_index < 1)) {
@@ -862,7 +878,7 @@ bool BKE_gpencil_stroke_smooth_strength(bGPDstroke *gps, int point_index, float
   }
   /* Only affect endpoints by a fraction of the normal influence */
   float inf = influence;
-  if (ELEM(point_index, 0, gps->totpoints - 1)) {
+  if (!is_cyclic && ELEM(point_index, 0, gps->totpoints - 1)) {
     inf *= 0.01f;
   }
   /* Limit max influence to reduce pop effect. */
@@ -884,9 +900,22 @@ bool BKE_gpencil_stroke_smooth_strength(bGPDstroke *gps, int point_index, float
     int before = point_index - step;
     int after = point_index + step;
 
-    CLAMP_MIN(before, 0);
-    CLAMP_MAX(after, gps->totpoints - 1);
-
+    if (is_cyclic) {
+      if (before < 0) {
+        /* Sub to end point (before is already negative). */
+        before = gps->totpoints + before;
+        CLAMP(before, 0, gps->totpoints - 1);
+      }
+      if (after > gps->totpoints - 1) {
+        /* Add to start point. */
+        after = after - gps->totpoints;
+        CLAMP(after, 0, gps->totpoints - 1);
+      }
+    }
+    else {
+      CLAMP_MIN(before, 0);
+      CLAMP_MAX(after, gps->totpoints - 1);
+    }
     pt1 = &gps->points[before];
     pt2 = &gps->points[after];
 
@@ -919,6 +948,7 @@ bool BKE_gpencil_stroke_smooth_strength(bGPDstroke *gps, int point_index, float
 bool BKE_gpencil_stroke_smooth_thickness(bGPDstroke *gps, int point_index, float influence)
 {
   bGPDspoint *ptb = &gps->points[point_index];
+  const bool is_cyclic = (gps->flag & GP_STROKE_CYCLIC) != 0;
 
   /* Do nothing if not enough points */
   if ((gps->totpoints <= 2) || (point_index < 1)) {
@@ -926,7 +956,7 @@ bool BKE_gpencil_stroke_smooth_thickness(bGPDstroke *gps, int point_index, float
   }
   /* Only affect endpoints by a fraction of the normal influence */
   float inf = influence;
-  if (ELEM(point_index, 0, gps->totpoints - 1)) {
+  if (!is_cyclic && ELEM(point_index, 0, gps->totpoints - 1)) {
     inf *= 0.01f;
   }
   /* Limit max influence to reduce pop effect. */
@@ -948,9 +978,22 @@ bool BKE_gpencil_stroke_smooth_thickness(bGPDstroke *gps, int point_index, float
     int before = point_index - step;
     int after = point_index + step;
 
-    CLAMP_MIN(before, 0);
-    CLAMP_MAX(after, gps->totpoints - 1);
-
+    if (is_cyclic) {
+      if (before < 0) {
+        /* Sub to end point (before is already negative). */
+        before = gps->totpoints + before;
+        CLAMP(before, 0, gps->totpoints - 1);
+      }
+      if (after > gps->totpoints - 1) {
+        /* Add to start point. */
+        after = after - gps->totpoints;
+        CLAMP(after, 0, gps->totpoints - 1);
+      }
+    }
+    else {
+      CLAMP_MIN(before, 0);
+      CLAMP_MAX(after, gps->totpoints - 1);
+    }
     pt1 = &gps->points[before];
     pt2 = &gps->points[after];
 
@@ -982,6 +1025,7 @@ bool BKE_gpencil_stroke_smooth_thickness(bGPDstroke *gps, int point_index, float
 bool BKE_gpencil_stroke_smooth_uv(bGPDstroke *gps, int point_index, float influence)
 {
   bGPDspoint *ptb = &gps->points[point_index];
+  const bool is_cyclic = (gps->flag & GP_STROKE_CYCLIC) != 0;
 
   /* Do nothing if not enough points */
   if (gps->totpoints <= 2) {
@@ -993,9 +1037,22 @@ bool BKE_gpencil_stroke_smooth_uv(bGPDstroke *gps, int point_index, float influe
   int before = point_index - 1;
   int after = point_index + 1;
 
-  CLAMP_MIN(before, 0);
-  CLAMP_MAX(after, gps->totpoints - 1);
-
+  if (is_cyclic) {
+    if (before < 0) {
+      /* Sub to end point (before is already negative). */
+      before = gps->totpoints + before;
+      CLAMP(before, 0, gps->totpoints - 1);
+    }
+    if (after > gps->totpoints - 1) {
+      /* Add to start point. */
+      after = after - gps->totpoints;
+      CLAMP(after, 0, gps->totpoints - 1);
+    }
+  }
+  else {
+    CLAMP_MIN(before, 0);
+    CLAMP_MAX(after, gps->totpoints - 1);
+  }
   pta = &gps->points[before];
   ptc = &gps->points[after];