Try to generate a GP3 stroke using modifier.

@@ -721,6 +721,8 @@ class GreasePencilRuntime {
   /* The frame on which the object was evaluated (only valid for evaluated object). */
   int eval_frame = 0;
 
+  struct ::LineartCache *lineart_cache;

@@ -891,0 +938,4 @@
+  if (md->type != eModifierType_GreasePencilLineart) {
+    return false;
+  }
+  LISTBASE_FOREACH (ModifierData *, gmd, &ob->modifiers) {

@@ -891,0 +947,4 @@
+    }
+  }
+  /* If we reach here it means md is not in ob's modifier stack. */
+  BLI_assert(false);

@@ -5423,0 +5681,4 @@
+  curves[writer.index_range().last() + 1] = up_to_point;
+
+  blender::float4x4 mat(gp_obmat_inverse);
+  drawing.strokes_for_write() = blender::ed::greasepencil::create_drawing_data(

@@ -5491,2 +5761,4 @@
                            modifier_calculation_flags);
 }
+
+void MOD_lineart_gpencil_generate_v3(LineartCache *cache,

@@ -5492,1 +5762,4 @@
 }
+
+void MOD_lineart_gpencil_generate_v3(LineartCache *cache,
+                                     Object *ob,

@@ -5493,0 +5763,4 @@
+
+void MOD_lineart_gpencil_generate_v3(LineartCache *cache,
+                                     Object *ob,
+                                     struct GreasePencilDrawing &drawing,

@@ -5493,0 +5773,4 @@
+                                     uchar mask_switches,
+                                     uchar material_mask_bits,
+                                     uchar intersection_mask,
+                                     int16_t thickness,

@@ -5493,0 +5803,4 @@
+
+  float gp_obmat_inverse[4][4];
+  invert_m4_m4(gp_obmat_inverse, ob->object_to_world);
+  lineart_gpencil_generate_v3(cache,

@@ -0,0 +706,4 @@
+  modifier_subpanel_register(region_type, "bake", "Bake", nullptr, bake_panel_draw, panel_type);
+}
+
+static void generate_strokes_actual(const ModifierData &md,

@@ -0,0 +738,4 @@
+      lmd.calculation_flags);
+}
+
+static void generate_strokes(ModifierData &md, Depsgraph *depsgraph, Object &ob, GreasePencil &gpd)

@@ -0,0 +740,4 @@
+
+static void generate_strokes(ModifierData &md, Depsgraph *depsgraph, Object &ob, GreasePencil &gpd)
+{
+  GreasePencilLineartModifierData &lmd = (GreasePencilLineartModifierData &)md;

@@ -0,0 +743,4 @@
+  GreasePencilLineartModifierData &lmd = (GreasePencilLineartModifierData &)md;
+
+  /* This will check whether layer/materials are non-null. */
+  if (is_disabled(nullptr, &md, false)) {

@@ -0,0 +759,4 @@
+    MOD_lineart_destroy_render_data_v3(&lmd);
+  }
+  else {
+    if (!(lmd.flags & LRT_GPENCIL_USE_CACHE)) {

@@ -0,0 +769,4 @@
+  }
+
+  /* Ensure we have a frame in the selected layer to put line art result in. */
+  bke::greasepencil::Layer &got_layer = node->as_layer();

@@ -0,0 +770,4 @@
+
+  /* Ensure we have a frame in the selected layer to put line art result in. */
+  bke::greasepencil::Layer &got_layer = node->as_layer();
+  got_layer.add_frame(0, 0, 0);

@@ -0,0 +826,4 @@
+    /*struct_name*/ "GreasePencilLineartModifierData",
+    /*struct_size*/ sizeof(GreasePencilLineartModifierData),
+    /*srna*/ &RNA_GreasePencilLineartModifier,
+    /*type*/ ModifierTypeType::Nonconstructive,

@@ -162,1 +162,4 @@
   ModifierApplyFlag flag;
+
+  /* Line Art modifier cache will exist until the end of modifier stack evaluation. */
+  struct ::LineartCache *lineart_cache;

@@ -1264,6 +1268,17 @@ GreasePencil *BKE_grease_pencil_copy_for_eval(const GreasePencil *grease_pencil_
   return grease_pencil;
 }
 
+static struct ::LineartCache *init_lineart_cache()

@@ -1267,0 +1273,4 @@
+  return MOD_lineart_init_cache();
+}
+
+static void clear_lineart_cache(struct ::LineartCache *lc)

@@ -1277,3 +1292,3 @@
   }
   ModifierApplyFlag apply_flag = use_render ? MOD_APPLY_RENDER : MOD_APPLY_USECACHE;
-  const ModifierEvalContext mectx = {depsgraph, object, apply_flag};
+  LineartCache *lineart_cache = init_lineart_cache();

@@ -1278,2 +1293,3 @@
   ModifierApplyFlag apply_flag = use_render ? MOD_APPLY_RENDER : MOD_APPLY_USECACHE;
-  const ModifierEvalContext mectx = {depsgraph, object, apply_flag};
+  LineartCache *lineart_cache = init_lineart_cache();
+  const ModifierEvalContext mectx = {depsgraph, object, apply_flag, lineart_cache};

@@ -1298,2 +1322,4 @@
     }
   }
+
+  clear_lineart_cache(lineart_cache);

@@ -911,6 +924,8 @@ LineartBoundingArea *MOD_lineart_get_parent_bounding_area(LineartData *ld, doubl
  */
 LineartBoundingArea *MOD_lineart_get_bounding_area(LineartData *ld, double x, double y);
 
+struct GreasePencilDrawing;

@@ -7962,0 +8328,4 @@
+      "Match the beginning of vertex group names from mesh objects, match all when left empty");
+  RNA_def_property_update(prop, 0, "rna_Modifier_update");
+
+  // prop = RNA_def_property(srna, "vertex_group", PROP_STRING, PROP_NONE);

@@ -17,6 +17,9 @@ set(INC
   ../render
   ../windowmanager
   ../../../intern/eigen
+  ../gpencil_modifiers_legacy

@@ -554,1 +557,4 @@
 
+/* Stores the maximum calculation range in the whole modifier stack for line art so the cache can
+ * cover everything that will be visible. */
+typedef struct GreasePencilLineartLimitInfo {

@@ -555,0 +558,4 @@
+/* Stores the maximum calculation range in the whole modifier stack for line art so the cache can
+ * cover everything that will be visible. */
+typedef struct GreasePencilLineartLimitInfo {
+  short edge_types;

@@ -555,0 +568,4 @@
+bool BKE_grease_pencil_has_lineart_modifier(const Object *ob);
+
+GreasePencilLineartLimitInfo BKE_grease_pencil_get_lineart_modifier_limits(
+    const struct Object *ob);

@@ -891,0 +905,4 @@
+  bool is_first = true;
+  LISTBASE_FOREACH (ModifierData *, md, &ob->modifiers) {
+    if (md->type == eModifierType_GreasePencilLineart) {
+      auto *lmd = reinterpret_cast<GreasePencilLineartModifierData *>(md);

@@ -891,0 +948,4 @@
+  if (md->type != eModifierType_GreasePencilLineart) {
+    return false;
+  }
+  LISTBASE_FOREACH (ModifierData *, i_md, &ob->modifiers) {

@@ -3547,0 +3554,4 @@
+void MOD_lineart_wrap_modifier_v3(LineartGpencilModifierData *lmd_legacy,
+                                  GreasePencilLineartModifierData *lmd)
+{
+  memcpy((reinterpret_cast<char *>(lmd)) + sizeof(ModifierData) +

@@ -5015,3 +5051,1 @@
-  if (lmd->calculation_flags & LRT_USE_CUSTOM_CAMERA) {
-    if (!lmd->source_camera ||
-        (lineart_camera = DEG_get_evaluated_object(depsgraph, lmd->source_camera))->type !=
+  if (lmd.calculation_flags & LRT_USE_CUSTOM_CAMERA) {

@@ -5493,0 +5786,4 @@
+    return;
+  }
+
+  blender::Array<blender::float3> positions(total_point_count);

@@ -162,1 +162,4 @@
   ModifierApplyFlag flag;
+
+  /* Line Art modifier cache will exist until the end of modifier stack evaluation. */
+  struct ::LineartCache *lineart_cache = nullptr;

@@ -1371,0 +1378,4 @@
+  GreasePencilLineartModifierData *first_lineart = BKE_grease_pencil_get_first_lineart_modifier(
+      object);
+  if (first_lineart) {
+    first_lineart->shared_cache = MOD_lineart_init_cache();

@@ -35,6 +35,7 @@
 
 #include "BLI_linklist.h"
 #include "BLI_listbase.h"
+#include "BLI_math_base.hh"

@@ -13,6 +13,8 @@
 #include "BLI_math_vector.h"
 #include "BLI_threads.h"
 
+#include "BKE_grease_pencil.hh"

@@ -3540,0 +3558,4 @@
+  LMD_WRAP(source_object);
+  LMD_WRAP(source_collection);
+  LMD_WRAP(target_material);
+  strcpy(lmd->source_vertex_group, lmd_legacy->source_vertex_group);

@@ -5486,0 +5674,4 @@
+
+  bool inverse_silhouette = modifier_flags & LRT_GPENCIL_INVERT_SILHOUETTE_FILTER;
+
+  blender::Vector<LineartChainWriteInfo> writer = {};

@@ -5486,0 +5803,4 @@
+  }
+
+  bke::CurvesGeometry new_curves;
+  new_curves.resize(total_point_count, stroke_count);

@@ -5486,0 +5876,4 @@
+  point_opacities.finish();
+  stroke_materials.finish();
+
+  drawing.strokes_for_write() = new_curves;

@@ -0,0 +157,4 @@
+ * 2) Shadow render buffer if 3rd stage reprojection is need for silhouette/lit/shaded region
+ * selection. Otherwise the shadow render buffer is deleted before this function returns.
+ */
+bool lineart_main_try_generate_shadow(struct Depsgraph *depsgraph,

@@ -10,9 +10,12 @@
 #include <climits>
 #include <cstdlib>
 
+#include "BLI_math_base.hh"

@@ -871,6 +871,76 @@ void BKE_modifier_path_init(char *path, int path_maxncpy, const char *name)
   BLI_path_join(path, path_maxncpy, blendfile_path[0] ? "//" : BKE_tempdir_session(), name);
 }
 
+GreasePencilLineartLimitInfo BKE_grease_pencil_get_lineart_modifier_limits(const Object *ob)

@@ -874,0 +893,4 @@
+  return info;
+}
+
+void BKE_grease_pencil_set_lineart_modifier_limits(ModifierData *md,

@@ -874,0 +894,4 @@
+}
+
+void BKE_grease_pencil_set_lineart_modifier_limits(ModifierData *md,
+                                                   const GreasePencilLineartLimitInfo *info,

@@ -874,0 +931,4 @@
+  return false;
+}
+
+GreasePencilLineartModifierData *BKE_grease_pencil_get_first_lineart_modifier(const Object *ob)

@@ -5486,0 +5796,4 @@
+
+    stroke_count++;
+
+    /* TODO: Debug random color feature not implemented for v3 yet. */

@@ -0,0 +733,4 @@
+
+  /* Ensure we have a frame in the selected layer to put line art result in. */
+  bke::greasepencil::Layer &layer = node->as_layer();
+  layer.add_frame(0, 0, 0);

@@ -0,0 +759,4 @@
+      lmd.mask_switches,
+      lmd.material_mask_bits,
+      lmd.intersection_mask,
+      (float)lmd.thickness / 1000,

@@ -11,6 +11,7 @@ set(INC
   ../draw
   ../functions
   ../gpencil_modifiers_legacy
+  ../gpencil_modifiers_legacy/intern/lineart

@@ -869,1 +870,3 @@
-void MOD_lineart_destroy_render_data(struct LineartGpencilModifierData *lmd);
+void MOD_lineart_wrap_modifier_v3(const LineartGpencilModifierData *lmd_legacy,
+                                  GreasePencilLineartModifierData *lmd);
+void MOD_lineart_unwrap_modifier_v3(LineartGpencilModifierData *lmd_legacy,

@@ -2990,0 +3057,4 @@
+
+typedef struct GreasePencilLineartModifierData {
+  ModifierData modifier;
+  GreasePencilModifierInfluenceData influence;

@@ -0,0 +793,4 @@
+  if (is_first_lineart) {
+    mmd->shared_cache = MOD_lineart_init_cache();
+    info = BKE_grease_pencil_get_lineart_modifier_limits(ctx->object);
+    LISTBASE_FOREACH (ModifierData *, imd, &ctx->object->modifiers) {

@@ -58,6 +58,10 @@
 
 #include "MEM_guardedalloc.h"
 
+/* For Line Art modifier cache calls. */

@@ -874,0 +879,4 @@
+    if (md->type == eModifierType_GreasePencilLineart) {
+      const auto *lmd = reinterpret_cast<const GreasePencilLineartModifierData *>(md);
+      if (is_first || (lmd->flags & MOD_LINEART_USE_CACHE)) {
+        info.min_level = std::min(int(info.min_level), int(lmd->level_start));

@@ -0,0 +398,4 @@
+  const int level_start = RNA_int_get(ptr, "level_start");
+  const int level_end = RNA_int_get(ptr, "level_end");
+  if (use_multiple_levels) {
+    return (std::max(level_start, level_end) > 0);

@@ -56,3 +65,4 @@
 #include <algorithm> /* For `min/max`. */
 
 using blender::int3;
+using namespace blender;

@@ -8184,0 +8270,4 @@
+  RNA_define_lib_overridable(true);
+
+  prop = RNA_def_property(srna, "use_custom_camera", PROP_BOOLEAN, PROP_NONE);
+  RNA_def_property_boolean_sdna(prop, nullptr, "calculation_flags", LRT_USE_CUSTOM_CAMERA);

@@ -0,0 +85,4 @@
+    return false;
+  }
+  ModifierData *imd = md.modifier.prev;
+  while (imd) {

@@ -0,0 +100,4 @@
+    return false;
+  }
+  ModifierData *imd = md.modifier.next;
+  while (imd) {

@@ -0,0 +158,4 @@
+                                const ModifierUpdateDepsgraphContext *ctx,
+                                const int mode)
+{
+  if (!c) {

@@ -1811,0 +1819,4 @@
+{
+  GreasePencilLineartModifierData *lmd = (GreasePencilLineartModifierData *)ptr->data;
+
+  CLAMP(value, 0, 128);

@@ -1811,0 +1828,4 @@
+{
+  GreasePencilLineartModifierData *lmd = (GreasePencilLineartModifierData *)ptr->data;
+
+  CLAMP(value, 0, 128);

@@ -5486,0 +5854,4 @@
+      int point_i = i + up_to_point;
+      float *point = (float *)&point_positions[point_i];
+      copy_v3_v3(point, eci->gpos);
+      point_radii.span[point_i] = thickness;

@@ -940,0 +968,4 @@
+                                     const int8_t source_type,
+                                     Object *source_object,
+                                     struct Collection *source_collection,
+                                     const int level_start,