Simplify modifier skeleton

@@ -0,0 +1,430 @@
+/* SPDX-FileCopyrightText: 2005 Blender Authors

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+  if (src_point_size == 0) {
+    return {};
+  }
+  OffsetIndices<int> points_by_curve = src_curves.points_by_curve();

@@ -0,0 +169,4 @@
+    }
+  });
+
+  bke::CurvesGeometry dst_curves = bke::curves::copy_only_curve_domain(src_curves);

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+  offset_indices::accumulate_counts_to_offsets(dst_curves.offsets_for_write());
+
+  int merged_points = 0;
+  Array<int> src_to_dst_indices(src_point_size);

@@ -0,0 +274,4 @@
+  const bke::CurvesGeometry &curves = drawing.strokes();
+  const IndexMask strokes = modifier::greasepencil::get_filtered_stroke_mask(
+      &ob, curves, mmd.influence, memory);
+

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+  switch (mmd.mode) {
+    case MOD_GREASE_PENCIL_SIMPLIFY_FIXED: {
+      const IndexMask points_to_delete = simplify_fixed(curves, mmd.step, memory);
+      drawing.strokes_for_write().remove_points(points_to_delete, {});

@@ -0,0 +298,4 @@
+      break;
+    }
+    case MOD_GREASE_PENCIL_SIMPLIFY_SAMPLE: {
+      drawing.strokes_for_write() = std::move(geometry::resample_to_length(

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+            }
+            return false;
+          });
+      drawing.strokes_for_write() = std::move(

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+          curves_merge_by_distance(curves, mmd.distance, points, {}));
+      break;
+    }
+    default:

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+                                const ModifierEvalContext *ctx,
+                                bke::GeometrySet *geometry_set)
+{
+  auto *mmd = reinterpret_cast<GreasePencilSimplifyModifierData *>(md);

@@ -0,0 +243,4 @@
+          for (const int dst_point_i : range) {
+            /* Create a separate mixer for every point to avoid allocating temporary buffers
+             * in the mixer the size of the result curves and to improve memory locality. */
+            bke::attribute_math::DefaultMixer<T> mixer{dst_attribute.span.slice(dst_point_i, 1)};