From 52a9e6554846eaaa92ab603e9f180ade4ddb8e6e Mon Sep 17 00:00:00 2001
From: Ares Deveaux <aresdevo@gmail.com>
Date: Sun, 2 Apr 2023 21:23:32 -0700
Subject: [PATCH 01/10] added functions

---
 scripts/startup/bl_ui/space_graph.py          |   1 +
 .../editors/animation/keyframes_general.c     |  47 +++++++
 .../editors/include/ED_keyframes_edit.h       |   1 +
 .../editors/space_graph/graph_intern.h        |   1 +
 .../blender/editors/space_graph/graph_ops.c   |   1 +
 .../editors/space_graph/graph_slider_ops.c    | 124 ++++++++++++++++++
 6 files changed, 175 insertions(+)

diff --git a/scripts/startup/bl_ui/space_graph.py b/scripts/startup/bl_ui/space_graph.py
index 999a9e3cef7..f1109693d66 100644
--- a/scripts/startup/bl_ui/space_graph.py
+++ b/scripts/startup/bl_ui/space_graph.py
@@ -329,6 +329,7 @@ class GRAPH_MT_slider(Menu):
         layout.operator("graph.breakdown", text="Breakdown")
         layout.operator("graph.blend_to_neighbor", text="Blend to Neighbor")
         layout.operator("graph.blend_to_default", text="Blend to Default Value")
+        layout.operator("graph.blend_to_offset", text="Blend to Offset")
         layout.operator("graph.ease", text="Ease")
         layout.operator("graph.gaussian_smooth", text="Smooth")
 
diff --git a/source/blender/editors/animation/keyframes_general.c b/source/blender/editors/animation/keyframes_general.c
index f1848e4cc42..ff52120234d 100644
--- a/source/blender/editors/animation/keyframes_general.c
+++ b/source/blender/editors/animation/keyframes_general.c
@@ -491,6 +491,53 @@ void ease_fcurve_segment(FCurve *fcu, FCurveSegment *segment, const float factor
 
 /* ---------------- */
 
+void blend_to_offset_fcurve_segment(FCurve *fcu, FCurveSegment *segment, const float factor)
+{
+  const BezTriple *left_key = fcurve_segment_start_get(fcu, segment->start_index);
+  const float left_x = left_key->vec[1][0];
+  const float left_y = left_key->vec[1][1];
+
+  const BezTriple *right_key = fcurve_segment_end_get(fcu, segment->start_index + segment->length);
+  const float right_x = right_key->vec[1][0];
+  const float right_y = right_key->vec[1][1];
+
+  const BezTriple *segment_first_key = fcurve_segment_start_get(fcu, segment->start_index + 1);
+  const float segment_first_key_y = segment_first_key->vec[1][1];
+
+  const BezTriple *segment_last_key = fcurve_segment_end_get(fcu, segment->start_index + segment->length - 1);
+  const float segment_last_key_y = segment_last_key->vec[1][1];
+
+  const float key_x_range = right_x - left_x;
+
+  /* Happens if there is only 1 key on the FCurve. Needs to be skipped because it
+   * would be a divide by 0. */
+  if (IS_EQF(key_x_range, 0.0f)) {
+    return;
+  }
+
+  /* The calculation needs diferent values for each side of the slider. */
+  const bool slider_right_side = factor > 0.5;
+
+  /* For this tool the calculations are made easier if each side of the slider goes from 0 to porisive 1. */
+  const float ping_pong_factor = fabs(factor * 2 - 1);
+  
+  float y_delta = 0;
+
+  if (slider_right_side) {
+      y_delta = right_y - segment_last_key_y;
+    }
+    else {
+      y_delta = left_y - segment_first_key_y;
+    }
+
+  for (int i = segment->start_index; i < segment->start_index + segment->length; i++) {
+    const float key_y_value = fcu->bezt[i].vec[1][1] + y_delta * ping_pong_factor;
+    move_key(&fcu->bezt[i], key_y_value);
+  }
+}
+
+/* ---------------- */
+
 void breakdown_fcurve_segment(FCurve *fcu, FCurveSegment *segment, const float factor)
 {
   const BezTriple *left_bezt = fcurve_segment_start_get(fcu, segment->start_index);
diff --git a/source/blender/editors/include/ED_keyframes_edit.h b/source/blender/editors/include/ED_keyframes_edit.h
index 69f103c6cba..dd89d8e7691 100644
--- a/source/blender/editors/include/ED_keyframes_edit.h
+++ b/source/blender/editors/include/ED_keyframes_edit.h
@@ -437,6 +437,7 @@ void smooth_fcurve_segment(struct FCurve *fcu,
                            int kernel_size,
                            double *kernel);
 void ease_fcurve_segment(struct FCurve *fcu, struct FCurveSegment *segment, float factor);
+void blend_to_offset_fcurve_segment(struct FCurve *fcu, struct FCurveSegment *segment, float factor);
 bool decimate_fcurve(struct bAnimListElem *ale, float remove_ratio, float error_sq_max);
 void blend_to_default_fcurve(struct PointerRNA *id_ptr, struct FCurve *fcu, float factor);
 /**
diff --git a/source/blender/editors/space_graph/graph_intern.h b/source/blender/editors/space_graph/graph_intern.h
index 7128f805a23..19e880298cd 100644
--- a/source/blender/editors/space_graph/graph_intern.h
+++ b/source/blender/editors/space_graph/graph_intern.h
@@ -114,6 +114,7 @@ void GRAPH_OT_clean(struct wmOperatorType *ot);
 void GRAPH_OT_blend_to_neighbor(struct wmOperatorType *ot);
 void GRAPH_OT_breakdown(struct wmOperatorType *ot);
 void GRAPH_OT_ease(struct wmOperatorType *ot);
+void GRAPH_OT_blend_to_offset(struct wmOperatorType *ot);
 void GRAPH_OT_decimate(struct wmOperatorType *ot);
 void GRAPH_OT_blend_to_default(struct wmOperatorType *ot);
 void GRAPH_OT_gaussian_smooth(struct wmOperatorType *ot);
diff --git a/source/blender/editors/space_graph/graph_ops.c b/source/blender/editors/space_graph/graph_ops.c
index b64884da06c..a287fa1768e 100644
--- a/source/blender/editors/space_graph/graph_ops.c
+++ b/source/blender/editors/space_graph/graph_ops.c
@@ -463,6 +463,7 @@ void graphedit_operatortypes(void)
   WM_operatortype_append(GRAPH_OT_blend_to_neighbor);
   WM_operatortype_append(GRAPH_OT_breakdown);
   WM_operatortype_append(GRAPH_OT_ease);
+  WM_operatortype_append(GRAPH_OT_blend_to_offset);
   WM_operatortype_append(GRAPH_OT_blend_to_default);
   WM_operatortype_append(GRAPH_OT_gaussian_smooth);
   WM_operatortype_append(GRAPH_OT_euler_filter);
diff --git a/source/blender/editors/space_graph/graph_slider_ops.c b/source/blender/editors/space_graph/graph_slider_ops.c
index 184bd8329e8..4dbd2c02f85 100644
--- a/source/blender/editors/space_graph/graph_slider_ops.c
+++ b/source/blender/editors/space_graph/graph_slider_ops.c
@@ -1060,6 +1060,130 @@ void GRAPH_OT_ease(wmOperatorType *ot)
                        1.0f);
 }
 
+/* -------------------------------------------------------------------- */
+/** \name Blend to Offset Operator
+ * \{ */
+
+static void blend_to_offset_graph_keys(bAnimContext *ac, const float factor)
+{
+  ListBase anim_data = {NULL, NULL};
+
+  ANIM_animdata_filter(ac, &anim_data, OPERATOR_DATA_FILTER, ac->data, ac->datatype);
+  LISTBASE_FOREACH (bAnimListElem *, ale, &anim_data) {
+    FCurve *fcu = (FCurve *)ale->key_data;
+    ListBase segments = find_fcurve_segments(fcu);
+
+    LISTBASE_FOREACH (FCurveSegment *, segment, &segments) {
+      blend_to_offset_fcurve_segment(fcu, segment, factor);
+    }
+
+    ale->update |= ANIM_UPDATE_DEFAULT;
+    BLI_freelistN(&segments);
+  }
+
+  ANIM_animdata_update(ac, &anim_data);
+  ANIM_animdata_freelist(&anim_data);
+}
+
+static void blend_to_offset_draw_status_header(bContext *C, tGraphSliderOp *gso)
+{
+  char status_str[UI_MAX_DRAW_STR];
+  char mode_str[32];
+  char slider_string[UI_MAX_DRAW_STR];
+
+  ED_slider_status_string_get(gso->slider, slider_string, UI_MAX_DRAW_STR);
+
+  strcpy(mode_str, TIP_("Blend to Offset Keys"));
+
+  if (hasNumInput(&gso->num)) {
+    char str_ofs[NUM_STR_REP_LEN];
+
+    outputNumInput(&gso->num, str_ofs, &gso->scene->unit);
+
+    BLI_snprintf(status_str, sizeof(status_str), "%s: %s", mode_str, str_ofs);
+  }
+  else {
+    BLI_snprintf(status_str, sizeof(status_str), "%s: %s", mode_str, slider_string);
+  }
+
+  ED_workspace_status_text(C, status_str);
+}
+
+static void blend_to_offset_modal_update(bContext *C, wmOperator *op)
+{
+  tGraphSliderOp *gso = op->customdata;
+
+  blend_to_offset_draw_status_header(C, gso);
+
+  /* Reset keyframes to the state at invoke. */
+  reset_bezts(gso);
+  const float factor = slider_factor_get_and_remember(op);
+  blend_to_offset_graph_keys(&gso->ac, factor);
+  WM_event_add_notifier(C, NC_ANIMATION | ND_KEYFRAME | NA_EDITED, NULL);
+}
+
+static int blend_to_offset_invoke(bContext *C, wmOperator *op, const wmEvent *event)
+{
+  const int invoke_result = graph_slider_invoke(C, op, event);
+
+  if (invoke_result == OPERATOR_CANCELLED) {
+    return invoke_result;
+  }
+
+  tGraphSliderOp *gso = op->customdata;
+  gso->modal_update = blend_to_offset_modal_update;
+  gso->factor_prop = RNA_struct_find_property(op->ptr, "factor");
+  blend_to_offset_draw_status_header(C, gso);
+
+  return invoke_result;
+}
+
+static int blend_to_offset_exec(bContext *C, wmOperator *op)
+{
+  bAnimContext ac;
+
+  /* Get editor data. */
+  if (ANIM_animdata_get_context(C, &ac) == 0) {
+    return OPERATOR_CANCELLED;
+  }
+
+  const float factor = RNA_float_get(op->ptr, "factor");
+
+  blend_to_offset_graph_keys(&ac, factor);
+
+  /* Set notifier that keyframes have changed. */
+  WM_event_add_notifier(C, NC_ANIMATION | ND_KEYFRAME | NA_EDITED, NULL);
+
+  return OPERATOR_FINISHED;
+}
+
+void GRAPH_OT_blend_to_offset(wmOperatorType *ot)
+{
+  /* Identifiers. */
+  ot->name = "Blend to Offset Keyframes";
+  ot->idname = "GRAPH_OT_blend_to_offset";
+  ot->description = "Shift selected keys to the value of the neighboring keys as a block";
+
+  /* API callbacks. */
+  ot->invoke = blend_to_offset_invoke;
+  ot->modal = graph_slider_modal;
+  ot->exec = blend_to_offset_exec;
+  ot->poll = graphop_editable_keyframes_poll;
+
+  /* Flags. */
+  ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
+
+  RNA_def_float_factor(ot->srna,
+                       "factor",
+                       0.5f,
+                       -FLT_MAX,
+                       FLT_MAX,
+                       "Curve Bend",
+                       "Control the bend of the curve",
+                       0.0f,
+                       1.0f);
+}
+
 /** \} */
 /* -------------------------------------------------------------------- */
 /** \name Gauss Smooth Operator
-- 
2.30.2


From 6c90f32d7e2e69c453ca9abcba376f831f0b1dcb Mon Sep 17 00:00:00 2001
From: Ares Deveaux <aresdevo@gmail.com>
Date: Sun, 2 Apr 2023 22:00:20 -0700
Subject: [PATCH 02/10] took away the "to" in the name

---
 scripts/startup/bl_ui/space_graph.py          |  2 +-
 .../editors/animation/keyframes_general.c     |  2 +-
 .../editors/include/ED_keyframes_edit.h       |  2 +-
 .../editors/space_graph/graph_intern.h        |  2 +-
 .../blender/editors/space_graph/graph_ops.c   |  2 +-
 .../editors/space_graph/graph_slider_ops.c    | 36 +++++++++----------
 6 files changed, 23 insertions(+), 23 deletions(-)

diff --git a/scripts/startup/bl_ui/space_graph.py b/scripts/startup/bl_ui/space_graph.py
index f1109693d66..f61db21dc88 100644
--- a/scripts/startup/bl_ui/space_graph.py
+++ b/scripts/startup/bl_ui/space_graph.py
@@ -329,7 +329,7 @@ class GRAPH_MT_slider(Menu):
         layout.operator("graph.breakdown", text="Breakdown")
         layout.operator("graph.blend_to_neighbor", text="Blend to Neighbor")
         layout.operator("graph.blend_to_default", text="Blend to Default Value")
-        layout.operator("graph.blend_to_offset", text="Blend to Offset")
+        layout.operator("graph.blend_offset", text="Blend Offset")
         layout.operator("graph.ease", text="Ease")
         layout.operator("graph.gaussian_smooth", text="Smooth")
 
diff --git a/source/blender/editors/animation/keyframes_general.c b/source/blender/editors/animation/keyframes_general.c
index ff52120234d..d6d1bbf9933 100644
--- a/source/blender/editors/animation/keyframes_general.c
+++ b/source/blender/editors/animation/keyframes_general.c
@@ -491,7 +491,7 @@ void ease_fcurve_segment(FCurve *fcu, FCurveSegment *segment, const float factor
 
 /* ---------------- */
 
-void blend_to_offset_fcurve_segment(FCurve *fcu, FCurveSegment *segment, const float factor)
+void blend_offset_fcurve_segment(FCurve *fcu, FCurveSegment *segment, const float factor)
 {
   const BezTriple *left_key = fcurve_segment_start_get(fcu, segment->start_index);
   const float left_x = left_key->vec[1][0];
diff --git a/source/blender/editors/include/ED_keyframes_edit.h b/source/blender/editors/include/ED_keyframes_edit.h
index dd89d8e7691..4bcd5b8486d 100644
--- a/source/blender/editors/include/ED_keyframes_edit.h
+++ b/source/blender/editors/include/ED_keyframes_edit.h
@@ -437,7 +437,7 @@ void smooth_fcurve_segment(struct FCurve *fcu,
                            int kernel_size,
                            double *kernel);
 void ease_fcurve_segment(struct FCurve *fcu, struct FCurveSegment *segment, float factor);
-void blend_to_offset_fcurve_segment(struct FCurve *fcu, struct FCurveSegment *segment, float factor);
+void blend_offset_fcurve_segment(struct FCurve *fcu, struct FCurveSegment *segment, float factor);
 bool decimate_fcurve(struct bAnimListElem *ale, float remove_ratio, float error_sq_max);
 void blend_to_default_fcurve(struct PointerRNA *id_ptr, struct FCurve *fcu, float factor);
 /**
diff --git a/source/blender/editors/space_graph/graph_intern.h b/source/blender/editors/space_graph/graph_intern.h
index 19e880298cd..6604004a7d4 100644
--- a/source/blender/editors/space_graph/graph_intern.h
+++ b/source/blender/editors/space_graph/graph_intern.h
@@ -114,7 +114,7 @@ void GRAPH_OT_clean(struct wmOperatorType *ot);
 void GRAPH_OT_blend_to_neighbor(struct wmOperatorType *ot);
 void GRAPH_OT_breakdown(struct wmOperatorType *ot);
 void GRAPH_OT_ease(struct wmOperatorType *ot);
-void GRAPH_OT_blend_to_offset(struct wmOperatorType *ot);
+void GRAPH_OT_blend_offset(struct wmOperatorType *ot);
 void GRAPH_OT_decimate(struct wmOperatorType *ot);
 void GRAPH_OT_blend_to_default(struct wmOperatorType *ot);
 void GRAPH_OT_gaussian_smooth(struct wmOperatorType *ot);
diff --git a/source/blender/editors/space_graph/graph_ops.c b/source/blender/editors/space_graph/graph_ops.c
index a287fa1768e..954277f2c67 100644
--- a/source/blender/editors/space_graph/graph_ops.c
+++ b/source/blender/editors/space_graph/graph_ops.c
@@ -463,7 +463,7 @@ void graphedit_operatortypes(void)
   WM_operatortype_append(GRAPH_OT_blend_to_neighbor);
   WM_operatortype_append(GRAPH_OT_breakdown);
   WM_operatortype_append(GRAPH_OT_ease);
-  WM_operatortype_append(GRAPH_OT_blend_to_offset);
+  WM_operatortype_append(GRAPH_OT_blend_offset);
   WM_operatortype_append(GRAPH_OT_blend_to_default);
   WM_operatortype_append(GRAPH_OT_gaussian_smooth);
   WM_operatortype_append(GRAPH_OT_euler_filter);
diff --git a/source/blender/editors/space_graph/graph_slider_ops.c b/source/blender/editors/space_graph/graph_slider_ops.c
index 4dbd2c02f85..ce4afa960c6 100644
--- a/source/blender/editors/space_graph/graph_slider_ops.c
+++ b/source/blender/editors/space_graph/graph_slider_ops.c
@@ -1061,10 +1061,10 @@ void GRAPH_OT_ease(wmOperatorType *ot)
 }
 
 /* -------------------------------------------------------------------- */
-/** \name Blend to Offset Operator
+/** \name Blend Offset Operator
  * \{ */
 
-static void blend_to_offset_graph_keys(bAnimContext *ac, const float factor)
+static void blend_offset_graph_keys(bAnimContext *ac, const float factor)
 {
   ListBase anim_data = {NULL, NULL};
 
@@ -1074,7 +1074,7 @@ static void blend_to_offset_graph_keys(bAnimContext *ac, const float factor)
     ListBase segments = find_fcurve_segments(fcu);
 
     LISTBASE_FOREACH (FCurveSegment *, segment, &segments) {
-      blend_to_offset_fcurve_segment(fcu, segment, factor);
+      blend_offset_fcurve_segment(fcu, segment, factor);
     }
 
     ale->update |= ANIM_UPDATE_DEFAULT;
@@ -1085,7 +1085,7 @@ static void blend_to_offset_graph_keys(bAnimContext *ac, const float factor)
   ANIM_animdata_freelist(&anim_data);
 }
 
-static void blend_to_offset_draw_status_header(bContext *C, tGraphSliderOp *gso)
+static void blend_offset_draw_status_header(bContext *C, tGraphSliderOp *gso)
 {
   char status_str[UI_MAX_DRAW_STR];
   char mode_str[32];
@@ -1093,7 +1093,7 @@ static void blend_to_offset_draw_status_header(bContext *C, tGraphSliderOp *gso)
 
   ED_slider_status_string_get(gso->slider, slider_string, UI_MAX_DRAW_STR);
 
-  strcpy(mode_str, TIP_("Blend to Offset Keys"));
+  strcpy(mode_str, TIP_("Blend Offset Keys"));
 
   if (hasNumInput(&gso->num)) {
     char str_ofs[NUM_STR_REP_LEN];
@@ -1109,20 +1109,20 @@ static void blend_to_offset_draw_status_header(bContext *C, tGraphSliderOp *gso)
   ED_workspace_status_text(C, status_str);
 }
 
-static void blend_to_offset_modal_update(bContext *C, wmOperator *op)
+static void blend_offset_modal_update(bContext *C, wmOperator *op)
 {
   tGraphSliderOp *gso = op->customdata;
 
-  blend_to_offset_draw_status_header(C, gso);
+  blend_offset_draw_status_header(C, gso);
 
   /* Reset keyframes to the state at invoke. */
   reset_bezts(gso);
   const float factor = slider_factor_get_and_remember(op);
-  blend_to_offset_graph_keys(&gso->ac, factor);
+  blend_offset_graph_keys(&gso->ac, factor);
   WM_event_add_notifier(C, NC_ANIMATION | ND_KEYFRAME | NA_EDITED, NULL);
 }
 
-static int blend_to_offset_invoke(bContext *C, wmOperator *op, const wmEvent *event)
+static int blend_offset_invoke(bContext *C, wmOperator *op, const wmEvent *event)
 {
   const int invoke_result = graph_slider_invoke(C, op, event);
 
@@ -1131,14 +1131,14 @@ static int blend_to_offset_invoke(bContext *C, wmOperator *op, const wmEvent *ev
   }
 
   tGraphSliderOp *gso = op->customdata;
-  gso->modal_update = blend_to_offset_modal_update;
+  gso->modal_update = blend_offset_modal_update;
   gso->factor_prop = RNA_struct_find_property(op->ptr, "factor");
-  blend_to_offset_draw_status_header(C, gso);
+  blend_offset_draw_status_header(C, gso);
 
   return invoke_result;
 }
 
-static int blend_to_offset_exec(bContext *C, wmOperator *op)
+static int blend_offset_exec(bContext *C, wmOperator *op)
 {
   bAnimContext ac;
 
@@ -1149,7 +1149,7 @@ static int blend_to_offset_exec(bContext *C, wmOperator *op)
 
   const float factor = RNA_float_get(op->ptr, "factor");
 
-  blend_to_offset_graph_keys(&ac, factor);
+  blend_offset_graph_keys(&ac, factor);
 
   /* Set notifier that keyframes have changed. */
   WM_event_add_notifier(C, NC_ANIMATION | ND_KEYFRAME | NA_EDITED, NULL);
@@ -1157,17 +1157,17 @@ static int blend_to_offset_exec(bContext *C, wmOperator *op)
   return OPERATOR_FINISHED;
 }
 
-void GRAPH_OT_blend_to_offset(wmOperatorType *ot)
+void GRAPH_OT_blend_offset(wmOperatorType *ot)
 {
   /* Identifiers. */
-  ot->name = "Blend to Offset Keyframes";
-  ot->idname = "GRAPH_OT_blend_to_offset";
+  ot->name = "Blend Offset Keyframes";
+  ot->idname = "GRAPH_OT_blend_offset";
   ot->description = "Shift selected keys to the value of the neighboring keys as a block";
 
   /* API callbacks. */
-  ot->invoke = blend_to_offset_invoke;
+  ot->invoke = blend_offset_invoke;
   ot->modal = graph_slider_modal;
-  ot->exec = blend_to_offset_exec;
+  ot->exec = blend_offset_exec;
   ot->poll = graphop_editable_keyframes_poll;
 
   /* Flags. */
-- 
2.30.2


From cf7810c00acd190dc0d99684b9ea8d0ce25dce26 Mon Sep 17 00:00:00 2001
From: Ares Deveaux <aresdevo@gmail.com>
Date: Sun, 2 Apr 2023 23:09:08 -0700
Subject: [PATCH 03/10] changed declarations of y_delta

---
 source/blender/editors/animation/keyframes_general.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/source/blender/editors/animation/keyframes_general.c b/source/blender/editors/animation/keyframes_general.c
index d6d1bbf9933..f3363bcf648 100644
--- a/source/blender/editors/animation/keyframes_general.c
+++ b/source/blender/editors/animation/keyframes_general.c
@@ -521,7 +521,7 @@ void blend_offset_fcurve_segment(FCurve *fcu, FCurveSegment *segment, const floa
   /* For this tool the calculations are made easier if each side of the slider goes from 0 to porisive 1. */
   const float ping_pong_factor = fabs(factor * 2 - 1);
   
-  float y_delta = 0;
+  float y_delta;
 
   if (slider_right_side) {
       y_delta = right_y - segment_last_key_y;
-- 
2.30.2


From 6cdaa215578d402e535e27b3866fa7e300d3950c Mon Sep 17 00:00:00 2001
From: Ares Deveaux <aresdevo@gmail.com>
Date: Mon, 3 Apr 2023 11:00:24 -0700
Subject: [PATCH 04/10] Fixed some formating

---
 .../editors/animation/keyframes_general.c      | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/source/blender/editors/animation/keyframes_general.c b/source/blender/editors/animation/keyframes_general.c
index f3363bcf648..551216ca0be 100644
--- a/source/blender/editors/animation/keyframes_general.c
+++ b/source/blender/editors/animation/keyframes_general.c
@@ -504,7 +504,8 @@ void blend_offset_fcurve_segment(FCurve *fcu, FCurveSegment *segment, const floa
   const BezTriple *segment_first_key = fcurve_segment_start_get(fcu, segment->start_index + 1);
   const float segment_first_key_y = segment_first_key->vec[1][1];
 
-  const BezTriple *segment_last_key = fcurve_segment_end_get(fcu, segment->start_index + segment->length - 1);
+  const BezTriple *segment_last_key = fcurve_segment_end_get(
+      fcu, segment->start_index + segment->length - 1);
   const float segment_last_key_y = segment_last_key->vec[1][1];
 
   const float key_x_range = right_x - left_x;
@@ -518,17 +519,18 @@ void blend_offset_fcurve_segment(FCurve *fcu, FCurveSegment *segment, const floa
   /* The calculation needs diferent values for each side of the slider. */
   const bool slider_right_side = factor > 0.5;
 
-  /* For this tool the calculations are made easier if each side of the slider goes from 0 to porisive 1. */
+  /* For this tool the calculations are made easier if each side of the slider goes from 0 to
+   * porisive 1. */
   const float ping_pong_factor = fabs(factor * 2 - 1);
-  
+
   float y_delta;
 
   if (slider_right_side) {
-      y_delta = right_y - segment_last_key_y;
-    }
-    else {
-      y_delta = left_y - segment_first_key_y;
-    }
+    y_delta = right_y - segment_last_key_y;
+  }
+  else {
+    y_delta = left_y - segment_first_key_y;
+  }
 
   for (int i = segment->start_index; i < segment->start_index + segment->length; i++) {
     const float key_y_value = fcu->bezt[i].vec[1][1] + y_delta * ping_pong_factor;
-- 
2.30.2


From 4fefa0dda6b3c17854435938fcd61f77033c2a50 Mon Sep 17 00:00:00 2001
From: Ares Deveaux <aresdevo@gmail.com>
Date: Mon, 10 Apr 2023 15:44:28 -0700
Subject: [PATCH 05/10] deleted the split on the vectors

---
 .../editors/animation/keyframes_general.c     | 20 ++-----------------
 1 file changed, 2 insertions(+), 18 deletions(-)

diff --git a/source/blender/editors/animation/keyframes_general.c b/source/blender/editors/animation/keyframes_general.c
index 551216ca0be..1b92d90e620 100644
--- a/source/blender/editors/animation/keyframes_general.c
+++ b/source/blender/editors/animation/keyframes_general.c
@@ -494,27 +494,11 @@ void ease_fcurve_segment(FCurve *fcu, FCurveSegment *segment, const float factor
 void blend_offset_fcurve_segment(FCurve *fcu, FCurveSegment *segment, const float factor)
 {
   const BezTriple *left_key = fcurve_segment_start_get(fcu, segment->start_index);
-  const float left_x = left_key->vec[1][0];
-  const float left_y = left_key->vec[1][1];
-
   const BezTriple *right_key = fcurve_segment_end_get(fcu, segment->start_index + segment->length);
-  const float right_x = right_key->vec[1][0];
-  const float right_y = right_key->vec[1][1];
 
   const BezTriple *segment_first_key = fcurve_segment_start_get(fcu, segment->start_index + 1);
-  const float segment_first_key_y = segment_first_key->vec[1][1];
-
   const BezTriple *segment_last_key = fcurve_segment_end_get(
       fcu, segment->start_index + segment->length - 1);
-  const float segment_last_key_y = segment_last_key->vec[1][1];
-
-  const float key_x_range = right_x - left_x;
-
-  /* Happens if there is only 1 key on the FCurve. Needs to be skipped because it
-   * would be a divide by 0. */
-  if (IS_EQF(key_x_range, 0.0f)) {
-    return;
-  }
 
   /* The calculation needs diferent values for each side of the slider. */
   const bool slider_right_side = factor > 0.5;
@@ -526,10 +510,10 @@ void blend_offset_fcurve_segment(FCurve *fcu, FCurveSegment *segment, const floa
   float y_delta;
 
   if (slider_right_side) {
-    y_delta = right_y - segment_last_key_y;
+    y_delta = right_key->vec[1][1] - segment_last_key->vec[1][1];
   }
   else {
-    y_delta = left_y - segment_first_key_y;
+    y_delta = left_key->vec[1][1] - segment_first_key->vec[1][1];
   }
 
   for (int i = segment->start_index; i < segment->start_index + segment->length; i++) {
-- 
2.30.2


From 960b6c41e206fd87e01262860888ebcc17b7be42 Mon Sep 17 00:00:00 2001
From: Ares Deveaux <aresdevo@gmail.com>
Date: Fri, 14 Apr 2023 02:18:05 -0700
Subject: [PATCH 06/10] another round of simplification

---
 .../editors/animation/keyframes_general.c     | 20 ++++++++-----------
 .../editors/space_graph/graph_slider_ops.c    |  3 +++
 2 files changed, 11 insertions(+), 12 deletions(-)

diff --git a/source/blender/editors/animation/keyframes_general.c b/source/blender/editors/animation/keyframes_general.c
index 1b92d90e620..49c4949ecf9 100644
--- a/source/blender/editors/animation/keyframes_general.c
+++ b/source/blender/editors/animation/keyframes_general.c
@@ -496,28 +496,24 @@ void blend_offset_fcurve_segment(FCurve *fcu, FCurveSegment *segment, const floa
   const BezTriple *left_key = fcurve_segment_start_get(fcu, segment->start_index);
   const BezTriple *right_key = fcurve_segment_end_get(fcu, segment->start_index + segment->length);
 
-  const BezTriple *segment_first_key = fcurve_segment_start_get(fcu, segment->start_index + 1);
-  const BezTriple *segment_last_key = fcurve_segment_end_get(
-      fcu, segment->start_index + segment->length - 1);
-
-  /* The calculation needs diferent values for each side of the slider. */
-  const bool slider_right_side = factor > 0.5;
+  const BezTriple segment_first_key = fcu->bezt[segment->start_index];
+  const BezTriple segment_last_key = fcu->bezt[segment->start_index + segment->length - 1];
 
   /* For this tool the calculations are made easier if each side of the slider goes from 0 to
-   * porisive 1. */
-  const float ping_pong_factor = fabs(factor * 2 - 1);
+   * positive 1. */
+  const float bidirectional_factor = fabs(factor * 2 - 1);
 
   float y_delta;
 
-  if (slider_right_side) {
-    y_delta = right_key->vec[1][1] - segment_last_key->vec[1][1];
+  if (factor > 0.5) {
+    y_delta = right_key->vec[1][1] - segment_last_key.vec[1][1];
   }
   else {
-    y_delta = left_key->vec[1][1] - segment_first_key->vec[1][1];
+    y_delta = left_key->vec[1][1] - segment_first_key.vec[1][1];
   }
 
   for (int i = segment->start_index; i < segment->start_index + segment->length; i++) {
-    const float key_y_value = fcu->bezt[i].vec[1][1] + y_delta * ping_pong_factor;
+    const float key_y_value = fcu->bezt[i].vec[1][1] + y_delta * bidirectional_factor;
     move_key(&fcu->bezt[i], key_y_value);
   }
 }
diff --git a/source/blender/editors/space_graph/graph_slider_ops.c b/source/blender/editors/space_graph/graph_slider_ops.c
index ce4afa960c6..9b2e6b6c36c 100644
--- a/source/blender/editors/space_graph/graph_slider_ops.c
+++ b/source/blender/editors/space_graph/graph_slider_ops.c
@@ -1135,6 +1135,9 @@ static int blend_offset_invoke(bContext *C, wmOperator *op, const wmEvent *event
   gso->factor_prop = RNA_struct_find_property(op->ptr, "factor");
   blend_offset_draw_status_header(C, gso);
 
+  // ED_slider_is_bidirectional_set(gso->slider, true);
+  // ED_slider_factor_set(gso->slider, 0.0f);
+
   return invoke_result;
 }
 
-- 
2.30.2


From fab764a6cf2843d1daf1a1be798ec6d6396d0720 Mon Sep 17 00:00:00 2001
From: Ares Deveaux <aresdevo@gmail.com>
Date: Fri, 14 Apr 2023 02:20:12 -0700
Subject: [PATCH 07/10] deleted 2 likes that I added to test the bidirectional
 slider

---
 source/blender/editors/space_graph/graph_slider_ops.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/source/blender/editors/space_graph/graph_slider_ops.c b/source/blender/editors/space_graph/graph_slider_ops.c
index 9b2e6b6c36c..ce4afa960c6 100644
--- a/source/blender/editors/space_graph/graph_slider_ops.c
+++ b/source/blender/editors/space_graph/graph_slider_ops.c
@@ -1135,9 +1135,6 @@ static int blend_offset_invoke(bContext *C, wmOperator *op, const wmEvent *event
   gso->factor_prop = RNA_struct_find_property(op->ptr, "factor");
   blend_offset_draw_status_header(C, gso);
 
-  // ED_slider_is_bidirectional_set(gso->slider, true);
-  // ED_slider_factor_set(gso->slider, 0.0f);
-
   return invoke_result;
 }
 
-- 
2.30.2


From c038ce005ff4af77e5dd8a9af475dcc6f22aca23 Mon Sep 17 00:00:00 2001
From: Ares Deveaux <aresdevo@gmail.com>
Date: Mon, 17 Apr 2023 21:04:26 -0700
Subject: [PATCH 08/10] added bidirectional sliders

---
 source/blender/editors/animation/keyframes_general.c  | 9 ++-------
 source/blender/editors/space_graph/graph_slider_ops.c | 2 ++
 2 files changed, 4 insertions(+), 7 deletions(-)

diff --git a/source/blender/editors/animation/keyframes_general.c b/source/blender/editors/animation/keyframes_general.c
index 49c4949ecf9..4f9e76ebf24 100644
--- a/source/blender/editors/animation/keyframes_general.c
+++ b/source/blender/editors/animation/keyframes_general.c
@@ -498,14 +498,9 @@ void blend_offset_fcurve_segment(FCurve *fcu, FCurveSegment *segment, const floa
 
   const BezTriple segment_first_key = fcu->bezt[segment->start_index];
   const BezTriple segment_last_key = fcu->bezt[segment->start_index + segment->length - 1];
-
-  /* For this tool the calculations are made easier if each side of the slider goes from 0 to
-   * positive 1. */
-  const float bidirectional_factor = fabs(factor * 2 - 1);
-
   float y_delta;
 
-  if (factor > 0.5) {
+  if (factor > 0) {
     y_delta = right_key->vec[1][1] - segment_last_key.vec[1][1];
   }
   else {
@@ -513,7 +508,7 @@ void blend_offset_fcurve_segment(FCurve *fcu, FCurveSegment *segment, const floa
   }
 
   for (int i = segment->start_index; i < segment->start_index + segment->length; i++) {
-    const float key_y_value = fcu->bezt[i].vec[1][1] + y_delta * bidirectional_factor;
+    const float key_y_value = fcu->bezt[i].vec[1][1] + y_delta * fabs(factor);
     move_key(&fcu->bezt[i], key_y_value);
   }
 }
diff --git a/source/blender/editors/space_graph/graph_slider_ops.c b/source/blender/editors/space_graph/graph_slider_ops.c
index ce4afa960c6..e464a3930d8 100644
--- a/source/blender/editors/space_graph/graph_slider_ops.c
+++ b/source/blender/editors/space_graph/graph_slider_ops.c
@@ -1134,6 +1134,8 @@ static int blend_offset_invoke(bContext *C, wmOperator *op, const wmEvent *event
   gso->modal_update = blend_offset_modal_update;
   gso->factor_prop = RNA_struct_find_property(op->ptr, "factor");
   blend_offset_draw_status_header(C, gso);
+  ED_slider_is_bidirectional_set(gso->slider, true);
+  ED_slider_factor_set(gso->slider, 0.0f);
 
   return invoke_result;
 }
-- 
2.30.2


From 45de734e6ba48b7d946f9bc0df21dec6bee65ed6 Mon Sep 17 00:00:00 2001
From: Ares Deveaux <aresdevo@gmail.com>
Date: Thu, 20 Apr 2023 12:46:52 -0700
Subject: [PATCH 09/10] corrected a small error in the operator

---
 source/blender/editors/space_graph/graph_slider_ops.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/source/blender/editors/space_graph/graph_slider_ops.c b/source/blender/editors/space_graph/graph_slider_ops.c
index e464a3930d8..2cb532fd904 100644
--- a/source/blender/editors/space_graph/graph_slider_ops.c
+++ b/source/blender/editors/space_graph/graph_slider_ops.c
@@ -1177,12 +1177,12 @@ void GRAPH_OT_blend_offset(wmOperatorType *ot)
 
   RNA_def_float_factor(ot->srna,
                        "factor",
-                       0.5f,
+                       0.0f,
                        -FLT_MAX,
                        FLT_MAX,
                        "Curve Bend",
                        "Control the bend of the curve",
-                       0.0f,
+                       -1.0f,
                        1.0f);
 }
 
-- 
2.30.2


From 5c93d1f2cffad40cfd8895a1ed6ccf8fbdfff782 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Sybren=20A=2E=20St=C3=BCvel?= <sybren@blender.org>
Date: Tue, 9 May 2023 15:55:26 +0200
Subject: [PATCH 10/10] Fixes for recent graph slider updates

---
 source/blender/editors/animation/keyframes_general.c  | 2 +-
 source/blender/editors/space_graph/graph_slider_ops.c | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/source/blender/editors/animation/keyframes_general.c b/source/blender/editors/animation/keyframes_general.c
index 539cbfc5092..5279636ba04 100644
--- a/source/blender/editors/animation/keyframes_general.c
+++ b/source/blender/editors/animation/keyframes_general.c
@@ -497,7 +497,7 @@ void blend_offset_fcurve_segment(FCurve *fcu, FCurveSegment *segment, const floa
 
   for (int i = segment->start_index; i < segment->start_index + segment->length; i++) {
     const float key_y_value = fcu->bezt[i].vec[1][1] + y_delta * fabs(factor);
-    move_key(&fcu->bezt[i], key_y_value);
+    BKE_fcurve_keyframe_move_value_with_handles(&fcu->bezt[i], key_y_value);
   }
 }
 
diff --git a/source/blender/editors/space_graph/graph_slider_ops.c b/source/blender/editors/space_graph/graph_slider_ops.c
index 272f8f2d42b..999e496cade 100644
--- a/source/blender/editors/space_graph/graph_slider_ops.c
+++ b/source/blender/editors/space_graph/graph_slider_ops.c
@@ -1041,7 +1041,7 @@ static int blend_offset_invoke(bContext *C, wmOperator *op, const wmEvent *event
   gso->modal_update = blend_offset_modal_update;
   gso->factor_prop = RNA_struct_find_property(op->ptr, "factor");
   blend_offset_draw_status_header(C, gso);
-  ED_slider_is_bidirectional_set(gso->slider, true);
+  ED_slider_factor_bounds_set(gso->slider, -1, 1);
   ED_slider_factor_set(gso->slider, 0.0f);
 
   return invoke_result;
-- 
2.30.2