scripts/startup/bl_ui/space_graph.py

@@ -338,6 +338,7 @@ class GRAPH_MT_key_blending(Menu):
         layout.operator("graph.blend_to_neighbor", text="Blend to Neighbor")
         layout.operator("graph.blend_to_default", text="Blend to Default Value")
         layout.operator("graph.ease", text="Ease")
+        layout.operator("graph.ease_to_ease", text="Ease to Ease")
         layout.operator("graph.blend_offset", text="Blend Offset")
         layout.operator("graph.blend_to_ease", text="Blend to Ease")
         layout.operator("graph.match_slope", text="Match Slope")

source/blender/editors/animation/keyframes_general.cc

@@ -702,6 +702,58 @@ void ease_fcurve_segment(FCurve *fcu, FCurveSegment *segment, const float factor
   }
 }
 
+static float s_curve(
+    const float x, const float slope, const float width, const float height, const float shift)
+{
+  /* Formula for 'S' curve we use for the "ease" sliders. The shift values move the curve verticaly
+   * or horizontaly. The range of the curve used is from 0 to 1 on "x" and "y" so we can scale it
+   * (width and height) and move it (xshift and y yshift) to crop the part of the curve we need.
+   * Slope determins how curvy the shape is */
+  float y = height * pow((x - shift), slope) /
+            (pow((x - shift), slope) + pow((width - (x - shift)), slope));
+
+  /* The curve has some noise beyond our margins so we clamp the values */
+  if (x > shift + width) {
+    y = height;
+  }
+  else if (x < shift) {
+    y = 0.0f;
+  }
+  return y;
+}
+
+void ease_to_ease_fcurve_segment(
+    FCurve *fcu, FCurveSegment *segment, const float factor, const float slope, const float width)
+{
+  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 float key_x_range = right_key->vec[1][0] - left_key->vec[1][0];
+  const float key_y_range = right_key->vec[1][1] - left_key->vec[1][1];
+
+  /* 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;
+  }
+
+  /* These ease values use the entire curve to get the "S" shape. The value 2.0 on the slope
+   * makes it a bit sharper. */
+  const float height = 1.0;
+  /* Using the factor on the xshift we are basicaly moving the curve horizontaly. */
+  const float shift = -factor;
+
+  for (int i = segment->start_index; i < segment->start_index + segment->length; i++) {
+
+    const float x = (fcu->bezt[i].vec[1][0] - left_key->vec[1][0]) / key_x_range;
+    const float ease = s_curve(x, slope, width, height, shift);
+
+    /* The ease variable basicaly act as a mask to molde the shape of the curve. */
+    const float key_y_value = left_key->vec[1][1] + key_y_range * ease;
+    BKE_fcurve_keyframe_move_value_with_handles(&fcu->bezt[i], key_y_value);
+  }
+}
+
 /* ---------------- */
 
 void blend_offset_fcurve_segment(FCurve *fcu, FCurveSegment *segment, const float factor)

source/blender/editors/include/ED_keyframes_edit.hh

@@ -470,6 +470,10 @@ void smooth_fcurve_segment(FCurve *fcu,
                            int kernel_size,
                            double *kernel);
 void ease_fcurve_segment(FCurve *fcu, FCurveSegment *segment, float factor);
+/** Snap the keys on the given FCurve segment to an S-Curve. By modifying the `factor` the part of
+ * the S-Curve that the keys are snapped to is moved on the x-axis.*/
+void ease_to_ease_fcurve_segment(
+    struct FCurve *fcu, struct FCurveSegment *segment, float factor, float slope, float width);
 enum tShearDirection {
   SHEAR_FROM_LEFT = 1,
   SHEAR_FROM_RIGHT,

source/blender/editors/space_graph/graph_intern.h

@@ -128,6 +128,7 @@ 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_ease_to_ease(struct wmOperatorType *ot);
 void GRAPH_OT_blend_offset(struct wmOperatorType *ot);
 void GRAPH_OT_blend_to_ease(struct wmOperatorType *ot);
 void GRAPH_OT_match_slope(struct wmOperatorType *ot);

source/blender/editors/space_graph/graph_ops.cc

@@ -470,6 +470,7 @@ void graphedit_operatortypes()
   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_ease_to_ease);
   WM_operatortype_append(GRAPH_OT_shear);
   WM_operatortype_append(GRAPH_OT_scale_average);
   WM_operatortype_append(GRAPH_OT_scale_from_neighbor);

source/blender/editors/space_graph/graph_slider_ops.cc

@@ -2469,3 +2469,123 @@ void GRAPH_OT_scale_from_neighbor(wmOperatorType *ot)
                "Reference Key",
                "Which end of the segment to use as a reference to scale from");
 }
+
+/* -------------------------------------------------------------------- */
+/** \name Ease Ease Operator
+ * \{ */
+
+static void ease_ease_graph_keys(bAnimContext *ac,
+                                 const float factor,
+                                 const float slope,
+                                 const float width)
+{
+  ListBase anim_data = {NULL, NULL};
+
+  ANIM_animdata_filter(
+      ac, &anim_data, OPERATOR_DATA_FILTER, ac->data, eAnimCont_Types(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) {
+      ease_to_ease_fcurve_segment(fcu, segment, factor, slope, width);
+    }
+
+    ale->update |= ANIM_UPDATE_DEFAULT;
+    BLI_freelistN(&segments);
+  }
+
+  ANIM_animdata_update(ac, &anim_data);
+  ANIM_animdata_freelist(&anim_data);
+}
+
+static void ease_ease_draw_status_header(bContext *C, tGraphSliderOp *gso)
+{
+  common_draw_status_header(C, gso, "Ease to Ease");
+}
+
+static void ease_ease_modal_update(bContext *C, wmOperator *op)
+{
+  tGraphSliderOp *gso = static_cast<tGraphSliderOp *>(op->customdata);
+
+  ease_ease_draw_status_header(C, gso);
+
+  /* Reset keyframes to the state at invoke. */
+  reset_bezts(gso);
+  const float factor = slider_factor_get_and_remember(op);
+  const float slope = RNA_float_get(op->ptr, "slope");
+  const float width = RNA_float_get(op->ptr, "width");
+
+  ease_ease_graph_keys(&gso->ac, factor, slope, width);
+  WM_event_add_notifier(C, NC_ANIMATION | ND_KEYFRAME | NA_EDITED, NULL);
+}
+
+static int ease_ease_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 = static_cast<tGraphSliderOp *>(op->customdata);
+  gso->modal_update = ease_ease_modal_update;
+  gso->factor_prop = RNA_struct_find_property(op->ptr, "factor");
+  ease_ease_draw_status_header(C, gso);
+  ED_slider_allow_overshoot_set(gso->slider, false, false);
+  ED_slider_factor_bounds_set(gso->slider, -1, 1);
+  ED_slider_factor_set(gso->slider, 0.0f);
+
+  return invoke_result;
+}
+
+static int ease_ease_exec(bContext *C, wmOperator *op)
+{
+  bAnimContext ac;
+
+  if (ANIM_animdata_get_context(C, &ac) == 0) {
+    return OPERATOR_CANCELLED;
+  }
+
+  const float factor = RNA_float_get(op->ptr, "factor");
+  const float slope = RNA_float_get(op->ptr, "slope");
+  const float width = RNA_float_get(op->ptr, "width");
+
+  ease_ease_graph_keys(&ac, factor, slope, width);
+
+  WM_event_add_notifier(C, NC_ANIMATION | ND_KEYFRAME | NA_EDITED, NULL);
+
+  return OPERATOR_FINISHED;
+}
+
+void GRAPH_OT_ease_to_ease(wmOperatorType *ot)
+{
+  /* Identifiers. */
+  ot->name = "Ease To Ease";
+  ot->idname = "GRAPH_OT_ease_to_ease";
+  ot->description = "Align keyframes on a ease-in or ease-out curve";
+
+  /* API callbacks. */
+  ot->invoke = ease_ease_invoke;
+  ot->modal = graph_slider_modal;
+  ot->exec = ease_ease_exec;
+  ot->poll = graphop_editable_keyframes_poll;
+
+  /* Flags. */
+  ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
+
+  RNA_def_float_factor(ot->srna,
+                       "factor",
+                       0.0f,
+                       -FLT_MAX,
+                       FLT_MAX,
+                       "Curve Bend",
+                       "Defines if the keys should be aligned on an ease-in or ease-out curve",
+                       -1.0f,
+                       1.0f);
+
+  RNA_def_float(ot->srna, "slope", 2.0f, 0.0f, FLT_MAX, "Slope", "Foo", 0.0f, 16.0f);
+  RNA_def_float(ot->srna, "width", 1.0f, -FLT_MAX, FLT_MAX, "Width", "Foo", -16.0f, 16.0f);
+}
+
+/** \} */