Try to generate a GP3 stroke using modifier.

@@ -2486,6 +2487,7 @@ typedef enum VolumeToMeshFlag {
   VOLUME_TO_MESH_USE_SMOOTH_SHADE = 1 << 0,
 } VolumeToMeshFlag;
 
+/* Enum in old dna file. */

@@ -7615,3 +7621,3 @@
   PropertyRNA *prop;
 
-  static const EnumPropertyItem color_mode_items[] = {
+    static const EnumPropertyItem color_mode_items[] = {

@@ -0,0 +58,4 @@
+#include "DEG_depsgraph.hh"
+#include "DEG_depsgraph_query.hh"
+
+using namespace blender;

@@ -0,0 +106,4 @@
+  return (mmd->flag & GP_NOISE_USE_RANDOM) != 0;
+}
+
+static float *noise_table(int len, int offset, int seed)

@@ -0,0 +126,4 @@
+static void deform_stroke(ModifierData *md,
+                          Depsgraph *depsgraph,
+                          Object *ob,
+                          bke::greasepencil::Drawing *drawing)

@@ -0,0 +136,4 @@
+  GreasePencilNoiseModifierData *mmd = (GreasePencilNoiseModifierData *)md;
+  /* Noise value in range [-1..1] */
+  float3 vec1, vec2;
+  const bool use_curve = (mmd->influence.flag & GREASE_PENCIL_INFLUENCE_USE_CUSTOM_CURVE);

@@ -0,0 +141,4 @@
+  const bool is_keyframe = (mmd->noise_mode == GP_NOISE_RANDOM_KEYFRAME);
+
+  /* Sanitize as it can create out of bound reads. */
+  float noise_scale = clamp_f(mmd->noise_scale, 0.0f, 1.0f);

@@ -0,0 +148,4 @@
+  MutableSpan<float3> positions = strokes.positions_for_write();
+  MutableSpan<float> radiis = drawing->radii_for_write();
+  MutableSpan<float> opacities = drawing->opacities_for_write();
+  OffsetIndices<int> curves = strokes.points_by_curve();

@@ -0,0 +221,4 @@
+        }
+
+        /* Vector orthogonal to normal. */
+        vec2 = math::cross(vec1, normals[point]);

@@ -0,0 +232,4 @@
+      if (mmd->factor_thickness > 0.0f) {
+        float noise = table_sample(noise_table_thickness,
+                                  local_point * noise_scale + fractf(mmd->noise_offset));
+        radiis[point] *= max_ff(1.0f + (noise * 2.0f - 1.0f) * weight * mmd->factor_thickness, 0.0f);

@@ -0,0 +233,4 @@
+        float noise = table_sample(noise_table_thickness,
+                                  local_point * noise_scale + fractf(mmd->noise_offset));
+        radiis[point] *= max_ff(1.0f + (noise * 2.0f - 1.0f) * weight * mmd->factor_thickness, 0.0f);
+        CLAMP_MIN(radiis[point], GPENCIL_STRENGTH_MIN);

@@ -0,0 +240,4 @@
+        float noise = table_sample(noise_table_strength,
+                                  local_point * noise_scale + fractf(mmd->noise_offset));
+        opacities[point] *= max_ff(1.0f - noise * weight * mmd->factor_strength, 0.0f);
+        CLAMP(radiis[point], GPENCIL_STRENGTH_MIN, 1.0f);

@@ -0,0 +147,4 @@
+  /* Calculate or get stroke normals. */
+  Span<float3> normals = strokes.evaluated_normals();
+  MutableSpan<float3> positions = strokes.positions_for_write();
+  MutableSpan<float> radiis = drawing->radii_for_write();

@@ -0,0 +243,4 @@
+                                blender::bke::GeometrySet *geometry_set)
+{
+  GreasePencilNoiseModifierData *mmd = (GreasePencilNoiseModifierData *)md;
+  GreasePencil *gp = geometry_set->get_grease_pencil_for_write();

@@ -1135,3 +1132,1 @@
-                                               const Span<int> offsets,
-                                               const Span<int> materials,
-                                               const float4x4 &matrix)
+bke::CurvesGeometry create_drawing_data(const Span<float3> positions,

@@ -200,6 +200,13 @@ IndexMask retrieve_editable_and_selected_elements(Object &object,
                                                   bke::AttrDomain selection_domain,
                                                   IndexMaskMemory &memory);
 
+bke::CurvesGeometry create_drawing_data(const Span<float3> positions,

@@ -17,6 +17,7 @@ set(INC
   ../render
   ../windowmanager
   ../../../intern/eigen
+  ../gpencil_modifiers_legacy

@@ -0,0 +63,4 @@
+
+static void init_data(ModifierData *md)
+{
+  GreasePencilNoiseModifierData *gpmd = (GreasePencilNoiseModifierData *)md;

@@ -0,0 +136,4 @@
+      &ob, strokes, mmd.influence, memory);
+
+  /* Noise value in range [-1..1] */
+  float3 up_vector;

@@ -0,0 +148,4 @@
+    return;
+  }
+
+  OffsetIndices<int> points_by_curve = strokes.points_by_curve();

@@ -0,0 +166,4 @@
+  }
+  int noise_len = ceilf(strokes.points_num() * noise_scale) + 2;
+
+  if (mmd.factor) {

@@ -0,0 +174,4 @@
+        noise_len, int(floor(mmd.noise_offset)), seed + 2);
+
+    filtered_strokes.foreach_index([&](const int stroke_i) {
+      int point_count = points_by_curve[stroke_i].size();

@@ -0,0 +177,4 @@
+      int point_count = points_by_curve[stroke_i].size();
+      for (const int local_point : points_by_curve[stroke_i].index_range()) {
+        int point = local_point + points_by_curve[stroke_i].start();
+        float weight = 1.0f;

@@ -0,0 +183,4 @@
+          weight *= BKE_curvemapping_evaluateF(mmd.influence.custom_curve, 0, value);
+        }
+        /* Vector orthogonal to normal. */
+        up_vector = math::normalize(math::cross(tangents[point], normals[point]));

@@ -0,0 +184,4 @@
+        }
+        /* Vector orthogonal to normal. */
+        up_vector = math::normalize(math::cross(tangents[point], normals[point]));
+        float noise = table_sample(noise_table_position,

@@ -0,0 +188,4 @@
+                                   point * noise_scale + fractf(mmd.noise_offset));
+        positions[point] += up_vector * (noise * 2.0f - 1.0f) * weight * mmd.factor * 0.1f;
+      }
+    });

@@ -0,0 +181,4 @@
+
+    filtered_strokes.foreach_index([&](const int stroke_i) {
+      const IndexRange points = points_by_curve[stroke_i];
+      for (const int point : points) {

@@ -0,0 +187,4 @@
+        const float3 bi_normal = math::normalize(math::cross(tangents[point], normals[point]));
+        const float noise = table_sample(noise_table_position,
+                                   point * noise_scale + fractf(mmd.noise_offset));
+        positions[point] += up_vector * (noise * 2.0f - 1.0f) * weight * mmd.factor * 0.1f;

@@ -0,0 +248,4 @@
+  int current_frame = DEG_get_evaluated_scene(ctx->depsgraph)->r.cfra;
+
+  IndexMaskMemory mask_memory;
+  IndexMask layer_mask = modifier::greasepencil::get_filtered_layer_mask(

@@ -0,0 +199,4 @@
+        noise_len, int(floor(mmd.noise_offset)), seed);
+
+    filtered_strokes.foreach_index([&](const int stroke_i) {
+      int point_count = points_by_curve[stroke_i].size();

@@ -0,0 +111,4 @@
+  return table;
+}
+
+BLI_INLINE float table_sample(Array<float> &table, float x)

@@ -0,0 +158,4 @@
+    }
+    else {
+      /* If change every keyframe, use the last keyframe. */
+      /* TODO: not correct. */

@@ -0,0 +122,4 @@
+static void deform_drawing(ModifierData &md,
+                           Depsgraph *depsgraph,
+                           Object &ob,
+                           bke::greasepencil::Drawing &drawing)

@@ -0,0 +250,4 @@
+  const IndexMask layer_mask = modifier::greasepencil::get_filtered_layer_mask(
+      grease_pencil, mmd->influence, mask_memory);
+  const Vector<bke::greasepencil::Drawing *> drawings =
+      modifier::greasepencil::get_drawings_for_write(grease_pencil, layer_mask, current_frame);

@@ -0,0 +252,4 @@
+  const Vector<bke::greasepencil::Drawing *> drawings =
+      modifier::greasepencil::get_drawings_for_write(grease_pencil, layer_mask, current_frame);
+
+  threading::parallel_for_each(drawings, [&](bke::greasepencil::Drawing *drawing) {

@@ -7789,6 +7890,7 @@ static void rna_def_modifier_grease_pencil_subdiv(BlenderRNA *brna)
   RNA_def_property_range(prop, 0, 65536);
   RNA_def_property_ui_range(prop, 0, 32, 1, 0);
   RNA_def_property_ui_text(prop, "Level", "Number of subdivisions");
+

@@ -0,0 +215,4 @@
+    Array<float> noise_table_strength = noise_table(
+        noise_len, int(floor(mmd.noise_offset)), seed + 3);
+
+    filtered_strokes.foreach_index([&](const int stroke_i) {

@@ -0,0 +111,4 @@
+  return table;
+}
+
+static float table_sample(Array<float> &table, float x)

@@ -0,0 +113,4 @@
+
+static float table_sample(Array<float> &table, float x)
+{
+  return math::interpolate(table[int(ceilf(x))], table[int(floor(x))], fractf(x));

@@ -0,0 +155,4 @@
+  seed += BLI_hash_string(md.name);
+  if (mmd.flag & GP_NOISE_USE_RANDOM) {
+    if (!is_keyframe) {
+      seed += cfra / mmd.step;

@@ -0,0 +162,4 @@
+      seed += start_frame_number;
+    }
+  }
+  int noise_len = ceilf(strokes.points_num() * noise_scale) + 2;

@@ -0,0 +186,4 @@
+        /* Vector orthogonal to normal. */
+        const float3 bi_normal = math::normalize(math::cross(tangents[point], normals[point]));
+        const float noise = table_sample(noise_table_position,
+                                         point * noise_scale + fractf(mmd.noise_offset));

@@ -0,0 +203,4 @@
+      for (const int point : points) {
+        const float weight = get_weight(points, point);
+        const float noise = table_sample(noise_table_thickness,
+                                         point * noise_scale + fractf(mmd.noise_offset));

@@ -0,0 +220,4 @@
+      for (const int point : points) {
+        const float weight = get_weight(points, point);
+        const float noise = table_sample(noise_table_strength,
+                                         point * noise_scale + fractf(mmd.noise_offset));

@@ -0,0 +6,4 @@
+ * \ingroup modifiers
+ */
+
+#include "BLI_hash.h"

@@ -0,0 +120,4 @@
+ * Apply noise effect based on stroke direction.
+ */
+static void deform_drawing(ModifierData &md,
+                           Depsgraph *depsgraph,

@@ -0,0 +122,4 @@
+static void deform_drawing(ModifierData &md,
+                           Depsgraph *depsgraph,
+                           const int start_frame_number,
+                           Object &ob,

@@ -0,0 +164,4 @@
+  }
+  int noise_len = ceilf(strokes.points_num() * noise_scale) + 2;
+
+  auto get_weight = [&](const IndexRange points, const int point_i) {

@@ -0,0 +173,4 @@
+  };
+
+  if (mmd.factor > 0.0f) {
+    Span<float3> normals = strokes.evaluated_normals();

@@ -0,0 +179,4 @@
+    Array<float> noise_table_position = noise_table(
+        noise_len, int(floor(mmd.noise_offset)), seed + 2);
+
+    filtered_strokes.foreach_index([&](const int stroke_i) {

@@ -0,0 +182,4 @@
+    filtered_strokes.foreach_index([&](const int stroke_i) {
+      const IndexRange points = points_by_curve[stroke_i];
+      for (const int point : points) {
+        float weight = get_weight(points, point);

@@ -0,0 +231,4 @@
+
+static void modify_geometry_set(ModifierData *md,
+                                const ModifierEvalContext *ctx,
+                                blender::bke::GeometrySet *geometry_set)

@@ -298,1 +298,4 @@
      "Deform volume based on noise or other vector fields"}, /* TODO: Use correct icon. */
+    {eModifierType_GreasePencilNoise,
+     "GREASEPENCIL_NOISE",
+     ICON_GREASEPENCIL,

@@ -0,0 +128,4 @@
+
+  const OffsetIndices<int> points_by_curve = strokes.points_by_curve();
+
+  int seed = mmd.seed + strokes.points_num();

@@ -0,0 +233,4 @@
+  const IndexMask layer_mask = modifier::greasepencil::get_filtered_layer_mask(
+      grease_pencil, mmd->influence, mask_memory);
+  const Vector<modifier::greasepencil::FrameDrawingInfo> drawing_infos =
+      modifier::greasepencil::get_drawing_infos_by_frame(

@@ -125,6 +125,7 @@ typedef enum eNoiseGpencil_Flag {
   GP_NOISE_MOD_UV = (1 << 9), /* Deprecated (only for versioning). */
   GP_NOISE_INVERT_LAYERPASS = (1 << 10),
   GP_NOISE_INVERT_MATERIAL = (1 << 11),
+  MOD_GREASE_PENCIL_NOISE_OPEN_INFLUENCE_PANEL = (1 << 12),

@@ -0,0 +159,4 @@
+    filtered_strokes.foreach_index(GrainSize(512), [&](const int stroke_i) {
+      const IndexRange points = points_by_curve[stroke_i];
+      const int noise_len = math::ceil(points.size() * noise_scale) + 2;
+      const Array<float> noise_table_positions = noise_table(

@@ -0,0 +219,4 @@
+                                const ModifierEvalContext *ctx,
+                                bke::GeometrySet *geometry_set)
+{
+  GreasePencilNoiseModifierData *mmd = reinterpret_cast<GreasePencilNoiseModifierData *>(md);