GPv3: Cutter tool, initial commit

@@ -1793,0 +1804,4 @@
+            label="Cutter",
+            icon="ops.gpencil.stroke_cutter",
+            cursor='KNIFE',
+            widget=None,

@@ -254,0 +262,4 @@
+
+  Vector<MutableDrawingInfo> editable_drawings;
+  if (!grease_pencil.has_active_layer()) {
+    return editable_drawings.as_span();

@@ -254,0 +267,4 @@
+  const Layer &layer = *grease_pencil.get_active_layer();
+  const std::optional<int> layer_index = grease_pencil.get_layer_index(layer);
+  if (!layer.is_editable() || !layer_index.has_value()) {
+    return editable_drawings.as_span();

@@ -305,0 +313,4 @@
+  ot->invoke = WM_gesture_lasso_invoke;
+  ot->modal = WM_gesture_lasso_modal;
+  ot->exec = greasepencil::grease_pencil_stroke_cutter_exec;
+  ot->poll = ed::greasepencil::editable_grease_pencil_poll;

@@ -0,0 +549,4 @@
+
+  /* Lambda function for executing the cutter on each drawing. */
+  const auto execute_cutter_on_drawing =
+      [&](const int layer_index, const int frame_number, Drawing &drawing) {

@@ -0,0 +570,4 @@
+
+        /* Compute bounding boxes of curves in screen space. The bounding boxes are used to speed
+         * up the search for intersecting curves. */
+        Array<rcti> screen_space_bbox(src.curves_num());

@@ -0,0 +589,4 @@
+
+        /* Apply cutter. */
+        bke::CurvesGeometry dst;
+        const bool cutted = stroke_cutter_find_and_remove_segments(

@@ -0,0 +592,4 @@
+        const bool cutted = stroke_cutter_find_and_remove_segments(
+            src, dst, mcoords, mcoords_len, screen_space_positions, screen_space_bbox, keep_caps);
+
+        if (cutted) {

@@ -0,0 +596,4 @@
+          /* Set the new geometry. */
+          drawing.geometry.wrap() = std::move(dst);
+          drawing.tag_topology_changed();
+          changed = true;

@@ -327,6 +352,7 @@ void ED_operatortypes_grease_pencil_draw()
   using namespace blender::ed::sculpt_paint;
   WM_operatortype_append(GREASE_PENCIL_OT_brush_stroke);
   WM_operatortype_append(GREASE_PENCIL_OT_draw_mode_toggle);
+  WM_operatortype_append(GREASE_PENCIL_OT_stroke_cutter);

@@ -34,6 +36,8 @@
 
 namespace blender::ed::sculpt_paint::greasepencil {
 
+using namespace blender::ed::greasepencil;

@@ -0,0 +34,4 @@
+ */
+enum class SegmentRangeIndex : uint8_t { Start, End };
+
+template<typename T> struct SegmentRange {

@@ -0,0 +230,4 @@
+  BLI_rcti_pad(&bbox_ab, BBOX_PADDING, BBOX_PADDING);
+
+  /* Loop all curves, looking for intersecting segments. */
+  threading::parallel_for(src.curves_range(), 512, [&](const IndexRange curves) {

@@ -0,0 +245,4 @@
+
+      /* Find intersecting curve segments. */
+      for (const int point_c : points) {
+        if (!is_cyclic[curve] && point_c == points.last()) {

@@ -0,0 +352,4 @@
+                                                             &distance_min,
+                                                             &distance_max);
+
+      /* Avoid orphant points at the end of a curve. */

@@ -0,0 +389,4 @@
+
+  /* When a curve end is reached and the curve is cyclic, we add an extra cutter segment for the
+   * cyclic second part. */
+  if (check_cyclic && is_cyclic[curve] &&

@@ -0,0 +442,4 @@
+    const IndexRange src_points = src_points_by_curve[src_curve];
+    for (const int src_point : src_points) {
+      /* Skip point when it is already part of a cutter segment. */
+      if (cutter_segments.point_is_in_segment(src_curve, src_point)) {

@@ -0,0 +595,4 @@
+  });
+
+  /* Apply cutter. */
+  std::optional<bke::CurvesGeometry> cutted_strokes = stroke_cutter_find_and_remove_segments(

@@ -0,0 +444,4 @@
+        }
+
+        /* Create new cutter segment. */
+        mutex.lock();

@@ -0,0 +156,4 @@
+  const float c2 = a2 * co_c[0] + b2 * co_c[1];
+
+  const float det = float(a1 * b2 - a2 * b1);
+  BLI_assert(det != 0.0f);

@@ -0,0 +158,4 @@
+  const float det = float(a1 * b2 - a2 * b1);
+  BLI_assert(det != 0.0f);
+
+  float2 isect;

@@ -0,0 +291,4 @@
+  const int8_t directions[2] = {-1, 1};
+
+  /* Walk along the curve in both directions. */
+  for (const int8_t direction : directions) {

@@ -0,0 +555,4 @@
+  }
+
+  /* Create the new curves geometry. */
+  bke::CurvesGeometry dst;

@@ -0,0 +693,4 @@
+    WM_event_add_notifier(C, NC_GEOM | ND_DATA, &grease_pencil);
+  }
+
+  return (changed ? OPERATOR_FINISHED : OPERATOR_CANCELLED);

@@ -0,0 +704,4 @@
+    return OPERATOR_PASS_THROUGH;
+  }
+
+  const int result = stroke_cutter_execute(op, C, mcoords);