2 files changed, 81 insertions, 6 deletions

diff --git a/source/blender/editors/transform/transform_mode_edge_slide.c b/source/blender/editors/transform/transform_mode_edge_slide.c
index 1972e1501b5..9a82296bfc0 100644
--- a/source/blender/editors/transform/transform_mode_edge_slide.c
+++ b/source/blender/editors/transform/transform_mode_edge_slide.c
@@ -96,24 +96,28 @@ typedef struct EdgeSlideParams {
 } EdgeSlideParams;
 
 /**
- * Get the first valid EdgeSlideData.
+ * Get the first valid TransDataContainer *.
  *
  * Note we cannot trust TRANS_DATA_CONTAINER_FIRST_OK because of multi-object that
  * may leave items with invalid custom data in the transform data container.
  */
-static EdgeSlideData *edgeSlideFirstGet(TransInfo *t)
+static TransDataContainer *edge_slide_container_first_ok(TransInfo *t)
 {
   FOREACH_TRANS_DATA_CONTAINER (t, tc) {
-    EdgeSlideData *sld = tc->custom.mode.data;
-    if (sld == NULL) {
-      continue;
+    if (tc->custom.mode.data) {
+      return tc;
     }
-    return sld;
   }
   BLI_assert(!"Should never happen, at least one EdgeSlideData should be valid");
   return NULL;
 }
 
+static EdgeSlideData *edgeSlideFirstGet(TransInfo *t)
+{
+  TransDataContainer *tc = edge_slide_container_first_ok(t);
+  return tc->custom.mode.data;
+}
+
 static void calcEdgeSlideCustomPoints(struct TransInfo *t)
 {
   EdgeSlideData *sld = edgeSlideFirstGet(t);
@@ -1254,6 +1258,71 @@ void drawEdgeSlide(TransInfo *t)
   }
 }
 
+static void edge_slide_snap_apply(TransInfo *t, float *value)
+{
+  TransDataContainer *tc = edge_slide_container_first_ok(t);
+  EdgeSlideParams *slp = t->custom.mode.data;
+  EdgeSlideData *sld_active = tc->custom.mode.data;
+  TransDataEdgeSlideVert *sv = &sld_active->sv[sld_active->curr_sv_index];
+  float snap_point[3], co_orig[3], co_dest[2][3], dvec[3];
+
+  copy_v3_v3(co_orig, sv->v_co_orig);
+  add_v3_v3v3(co_dest[0], co_orig, sv->dir_side[0]);
+  add_v3_v3v3(co_dest[1], co_orig, sv->dir_side[1]);
+  if (tc->use_local_mat) {
+    mul_m4_v3(tc->mat, co_orig);
+    mul_m4_v3(tc->mat, co_dest[0]);
+    mul_m4_v3(tc->mat, co_dest[1]);
+  }
+
+  getSnapPoint(t, dvec);
+  sub_v3_v3(dvec, t->tsnap.snapTarget);
+  add_v3_v3v3(snap_point, co_orig, dvec);
+
+  float perc = *value;
+  int side_index;
+  if (slp->use_even == false) {
+    const bool is_clamp = !(t->flag & T_ALT_TRANSFORM);
+    if (is_clamp) {
+      side_index = perc < 0.0f;
+    }
+    else {
+      side_index = sld_active->curr_side_unclamp;
+    }
+    perc = line_point_factor_v3(snap_point, co_orig, co_dest[side_index]);
+    if (side_index) {
+      perc *= -1;
+    }
+  }
+  else {
+    /* Could be pre-calculated. */
+    float t_mid = line_point_factor_v3(
+        (float[3]){0.0f, 0.0f, 0.0f}, sv->dir_side[0], sv->dir_side[1]);
+
+    float t_snap = line_point_factor_v3(snap_point, co_dest[0], co_dest[1]);
+    side_index = t_snap >= t_mid;
+    perc = line_point_factor_v3(snap_point, co_orig, co_dest[side_index]);
+    if (!side_index) {
+      perc = (1.0f - perc) * t_mid;
+    }
+    else {
+      perc = perc * (1.0f - t_mid) + t_mid;
+    }
+
+    if (slp->flipped) {
+      perc = 1.0f - perc;
+    }
+
+    perc = (2 * perc) - 1.0f;
+
+    if (!slp->flipped) {
+      perc *= -1;
+    }
+  }
+
+  *value = perc;
+}
+
 void doEdgeSlide(TransInfo *t, float perc)
 {
   EdgeSlideParams *slp = t->custom.mode.data;
@@ -1365,6 +1434,7 @@ static void applyEdgeSlide(TransInfo *t, const int UNUSED(mval[2]))
 
   final = t->values[0];
 
+  applySnapping(t, &final);
   snapGridIncrement(t, &final);
 
   /* only do this so out of range values are not displayed */
@@ -1413,6 +1483,8 @@ void initEdgeSlide_ex(
   t->mode = TFM_EDGE_SLIDE;
   t->transform = applyEdgeSlide;
   t->handleEvent = handleEventEdgeSlide;
+  t->tsnap.applySnap = edge_slide_snap_apply;
+  t->tsnap.distance = transform_snap_distance_len_squared_fn;
 
   {
     EdgeSlideParams *slp = MEM_callocN(sizeof(*slp), __func__);
diff --git a/source/blender/editors/transform/transform_snap.c b/source/blender/editors/transform/transform_snap.c
index a9b3b7448ef..aaf5b55c4e3 100644
--- a/source/blender/editors/transform/transform_snap.c
+++ b/source/blender/editors/transform/transform_snap.c
@@ -127,6 +127,9 @@ bool transformModeUseSnap(const TransInfo *t)
   if (t->mode == TFM_VERT_SLIDE) {
     return true;
   }
+  if (t->mode == TFM_EDGE_SLIDE) {
+    return true;
+  }
 
   return false;
 }