Test: Retrieve original mesh information from the editmesh

release/scripts/startup/bl_ui/properties_data_mesh.py

@@ -411,6 +411,8 @@ class DATA_PT_shape_keys(MeshButtonsPanel, Panel):
                 row.active = enable_edit_value
                 row.prop(key, "eval_time")
 
+        layout.prop(ob, "add_rest_position_attribute")
+
 
 class DATA_PT_uv_texture(MeshButtonsPanel, Panel):
     bl_label = "UV Maps"

release/scripts/startup/nodeitems_builtins.py

@@ -73,6 +73,7 @@ def curve_node_items(context):
     yield NodeItem("GeometryNodeCurveLength")
     yield NodeItem("GeometryNodeCurveToMesh")
     yield NodeItem("GeometryNodeCurveToPoints")
+    yield NodeItem("GeometryNodeDeformCurvesWithSurface")
     yield NodeItem("GeometryNodeFillCurve")
     yield NodeItem("GeometryNodeFilletCurve")
     yield NodeItem("GeometryNodeResampleCurve")

source/blender/blenkernel/BKE_mesh.h

@@ -710,7 +710,8 @@ void BKE_mesh_calc_normals_split(struct Mesh *mesh);
  * to split geometry along sharp edges.
  */
 void BKE_mesh_calc_normals_split_ex(struct Mesh *mesh,
-                                    struct MLoopNorSpaceArray *r_lnors_spacearr);
+                                    struct MLoopNorSpaceArray *r_lnors_spacearr,
+                                    float (*r_corner_normals)[3]);
 
 /**
  * Higher level functions hiding most of the code needed around call to

source/blender/blenkernel/BKE_node.h

@@ -1501,6 +1501,7 @@ struct TexResult;
 #define GEO_NODE_MESH_TO_VOLUME 1164
 #define GEO_NODE_UV_UNWRAP 1165
 #define GEO_NODE_UV_PACK_ISLANDS 1166
+#define GEO_NODE_DEFORM_CURVES_ON_SURFACE 1167
 
 /** \} */
 

source/blender/blenkernel/intern/DerivedMesh.cc

@@ -66,6 +66,9 @@
 #  include "DNA_userdef_types.h"
 #endif
 
+using blender::float3;
+using blender::IndexRange;
+
 /* very slow! enable for testing only! */
 //#define USE_MODIFIER_VALIDATE
 
@@ -814,6 +817,25 @@ static void mesh_calc_modifiers(struct Depsgraph *depsgraph,
   /* Clear errors before evaluation. */
   BKE_modifiers_clear_errors(ob);
 
+  if (ob->modifier_flag & OB_MODIFIER_FLAG_ADD_REST_POSITION) {
+    if (mesh_final == nullptr) {
+      mesh_final = BKE_mesh_copy_for_eval(mesh_input, true);
+      ASSERT_IS_VALID_MESH(mesh_final);
+    }
+    float3 *rest_positions = static_cast<float3 *>(CustomData_add_layer_named(&mesh_final->vdata,
+                                                                              CD_PROP_FLOAT3,
+                                                                              CD_DEFAULT,
+                                                                              nullptr,
+                                                                              mesh_final->totvert,
+                                                                              "rest_position"));
+    blender::threading::parallel_for(
+        IndexRange(mesh_final->totvert), 1024, [&](const IndexRange range) {
+          for (const int i : range) {
+            rest_positions[i] = mesh_final->mvert[i].co;
+          }
+        });
+  }
+
   /* Apply all leading deform modifiers. */
   if (use_deform) {
     for (; md; md = md->next, md_datamask = md_datamask->next) {

source/blender/blenkernel/intern/mesh.cc

@@ -1922,9 +1922,25 @@ void BKE_mesh_vert_coords_apply_with_mat4(Mesh *mesh,
   BKE_mesh_tag_coords_changed(mesh);
 }
 
-void BKE_mesh_calc_normals_split_ex(Mesh *mesh, MLoopNorSpaceArray *r_lnors_spacearr)
+static float (*ensure_corner_normal_layer(Mesh &mesh))[3]
 {
   float(*r_loopnors)[3];
+  if (CustomData_has_layer(&mesh.ldata, CD_NORMAL)) {
+    r_loopnors = (float(*)[3])CustomData_get_layer(&mesh.ldata, CD_NORMAL);
+    memset(r_loopnors, 0, sizeof(float[3]) * mesh.totloop);
+  }
+  else {
+    r_loopnors = (float(*)[3])CustomData_add_layer(
+        &mesh.ldata, CD_NORMAL, CD_CALLOC, nullptr, mesh.totloop);
+    CustomData_set_layer_flag(&mesh.ldata, CD_NORMAL, CD_FLAG_TEMPORARY);
+  }
+  return r_loopnors;
+}
+
+void BKE_mesh_calc_normals_split_ex(Mesh *mesh,
+                                    MLoopNorSpaceArray *r_lnors_spacearr,
+                                    float (*r_corner_normals)[3])
+{
   short(*clnors)[2] = nullptr;
 
   /* Note that we enforce computing clnors when the clnor space array is requested by caller here.
@@ -1934,16 +1950,6 @@ void BKE_mesh_calc_normals_split_ex(Mesh *mesh, MLoopNorSpaceArray *r_lnors_spac
                                  ((mesh->flag & ME_AUTOSMOOTH) != 0);
   const float split_angle = (mesh->flag & ME_AUTOSMOOTH) != 0 ? mesh->smoothresh : (float)M_PI;
 
-  if (CustomData_has_layer(&mesh->ldata, CD_NORMAL)) {
-    r_loopnors = (float(*)[3])CustomData_get_layer(&mesh->ldata, CD_NORMAL);
-    memset(r_loopnors, 0, sizeof(float[3]) * mesh->totloop);
-  }
-  else {
-    r_loopnors = (float(*)[3])CustomData_add_layer(
-        &mesh->ldata, CD_NORMAL, CD_CALLOC, nullptr, mesh->totloop);
-    CustomData_set_layer_flag(&mesh->ldata, CD_NORMAL, CD_FLAG_TEMPORARY);
-  }
-
   /* may be nullptr */
   clnors = (short(*)[2])CustomData_get_layer(&mesh->ldata, CD_CUSTOMLOOPNORMAL);
 
@@ -1953,7 +1959,7 @@ void BKE_mesh_calc_normals_split_ex(Mesh *mesh, MLoopNorSpaceArray *r_lnors_spac
                               mesh->medge,
                               mesh->totedge,
                               mesh->mloop,
-                              r_loopnors,
+                              r_corner_normals,
                               mesh->totloop,
                               mesh->mpoly,
                               BKE_mesh_poly_normals_ensure(mesh),
@@ -1969,7 +1975,7 @@ void BKE_mesh_calc_normals_split_ex(Mesh *mesh, MLoopNorSpaceArray *r_lnors_spac
 
 void BKE_mesh_calc_normals_split(Mesh *mesh)
 {
-  BKE_mesh_calc_normals_split_ex(mesh, nullptr);
+  BKE_mesh_calc_normals_split_ex(mesh, nullptr, ensure_corner_normal_layer(*mesh));
 }
 
 /* Split faces helper functions. */
@@ -2188,7 +2194,8 @@ void BKE_mesh_split_faces(Mesh *mesh, bool free_loop_normals)
 
   MLoopNorSpaceArray lnors_spacearr = {nullptr};
   /* Compute loop normals and loop normal spaces (a.k.a. smooth fans of faces around vertices). */
-  BKE_mesh_calc_normals_split_ex(mesh, &lnors_spacearr);
+
+  BKE_mesh_calc_normals_split_ex(mesh, &lnors_spacearr, ensure_corner_normal_layer(*mesh));
   /* Stealing memarena from loop normals space array. */
   MemArena *memarena = lnors_spacearr.mem;
 

source/blender/blenkernel/intern/node.cc

@@ -4749,6 +4749,7 @@ static void registerGeometryNodes()
   register_node_type_geo_curve_to_mesh();
   register_node_type_geo_curve_to_points();
   register_node_type_geo_curve_trim();
+  register_node_type_geo_deform_curves_on_surface();
   register_node_type_geo_delete_geometry();
   register_node_type_geo_duplicate_elements();
   register_node_type_geo_distribute_points_on_faces();

source/blender/editors/curves/intern/curves_add.cc

@@ -6,12 +6,96 @@
 
 #include "BLI_rand.hh"
 
+#include "BKE_context.h"
 #include "BKE_curves.hh"
+#include "BKE_node.h"
+#include "BKE_node_runtime.hh"
 
 #include "ED_curves.h"
+#include "ED_node.h"
+#include "ED_object.h"
+
+#include "DNA_modifier_types.h"
+#include "DNA_node_types.h"
+#include "DNA_object_types.h"
 
 namespace blender::ed::curves {
 
+static bool has_surface_deformation_node(const bNodeTree &ntree)
+{
+  LISTBASE_FOREACH (const bNode *, node, &ntree.nodes) {
+    if (node->type == GEO_NODE_DEFORM_CURVES_ON_SURFACE) {
+      return true;
+    }
+    if (node->type == NODE_GROUP) {
+      if (node->id != nullptr) {
+        if (has_surface_deformation_node(*reinterpret_cast<const bNodeTree *>(node->id))) {
+          return true;
+        }
+      }
+    }
+  }
+  return false;
+}
+
+static bool has_surface_deformation_node(const Object &curves_ob)
+{
+  LISTBASE_FOREACH (const ModifierData *, md, &curves_ob.modifiers) {
+    if (md->type != eModifierType_Nodes) {
+      continue;
+    }
+    const NodesModifierData *nmd = reinterpret_cast<const NodesModifierData *>(md);
+    if (nmd->node_group == nullptr) {
+      continue;
+    }
+    if (has_surface_deformation_node(*nmd->node_group)) {
+      return true;
+    }
+  }
+  return false;
+}
+
+void ensure_surface_deformation_node_exists(bContext &C, Object &curves_ob)
+{
+  if (has_surface_deformation_node(curves_ob)) {
+    return;
+  }
+
+  Main *bmain = CTX_data_main(&C);
+  Scene *scene = CTX_data_scene(&C);
+
+  ModifierData *md = ED_object_modifier_add(
+      nullptr, bmain, scene, &curves_ob, "Surface Deform", eModifierType_Nodes);
+  NodesModifierData &nmd = *reinterpret_cast<NodesModifierData *>(md);
+  nmd.node_group = ntreeAddTree(bmain, "Surface Deform", "GeometryNodeTree");
+
+  bNodeTree *ntree = nmd.node_group;
+  ntreeAddSocketInterface(ntree, SOCK_IN, "NodeSocketGeometry", "Geometry");
+  ntreeAddSocketInterface(ntree, SOCK_OUT, "NodeSocketGeometry", "Geometry");
+  bNode *group_input = nodeAddStaticNode(&C, ntree, NODE_GROUP_INPUT);
+  bNode *group_output = nodeAddStaticNode(&C, ntree, NODE_GROUP_OUTPUT);
+  bNode *deform_node = nodeAddStaticNode(&C, ntree, GEO_NODE_DEFORM_CURVES_ON_SURFACE);
+
+  ED_node_tree_propagate_change(&C, bmain, nmd.node_group);
+
+  nodeAddLink(ntree,
+              group_input,
+              static_cast<bNodeSocket *>(group_input->outputs.first),
+              deform_node,
+              nodeFindSocket(deform_node, SOCK_IN, "Curves"));
+  nodeAddLink(ntree,
+              deform_node,
+              nodeFindSocket(deform_node, SOCK_OUT, "Curves"),
+              group_output,
+              static_cast<bNodeSocket *>(group_output->inputs.first));
+
+  group_input->locx = -200;
+  group_output->locx = 200;
+  deform_node->locx = 0;
+
+  ED_node_tree_propagate_change(&C, bmain, nmd.node_group);
+}
+
 bke::CurvesGeometry primitive_random_sphere(const int curves_size, const int points_per_curve)
 {
   bke::CurvesGeometry curves(points_per_curve * curves_size, curves_size);

source/blender/editors/curves/intern/curves_ops.cc

@@ -944,6 +944,88 @@ static void SCULPT_CURVES_OT_select_all(wmOperatorType *ot)
   WM_operator_properties_select_all(ot);
 }
 
+namespace surface_set {
+
+static bool surface_set_poll(bContext *C)
+{
+  const Object *object = CTX_data_active_object(C);
+  if (object == nullptr) {
+    return false;
+  }
+  if (object->type != OB_MESH) {
+    return false;
+  }
+  return true;
+}
+
+static int surface_set_exec(bContext *C, wmOperator *op)
+{
+  Main *bmain = CTX_data_main(C);
+  Scene *scene = CTX_data_scene(C);
+
+  Object &new_surface_ob = *CTX_data_active_object(C);
+
+  Mesh &new_surface_mesh = *static_cast<Mesh *>(new_surface_ob.data);
+  const char *new_uv_map_name = CustomData_get_active_layer_name(&new_surface_mesh.ldata,
+                                                                 CD_MLOOPUV);
+
+  CTX_DATA_BEGIN (C, Object *, selected_ob, selected_objects) {
+    if (selected_ob->type != OB_CURVES) {
+      continue;
+    }
+    Object &curves_ob = *selected_ob;
+    Curves &curves_id = *static_cast<Curves *>(curves_ob.data);
+
+    MEM_SAFE_FREE(curves_id.surface_uv_map);
+    if (new_uv_map_name != nullptr) {
+      curves_id.surface_uv_map = BLI_strdup(new_uv_map_name);
+    }
+
+    bool missing_uvs;
+    bool invalid_uvs;
+    snap_curves_to_surface::snap_curves_to_surface_exec_object(
+        curves_ob,
+        new_surface_ob,
+        snap_curves_to_surface::AttachMode::Nearest,
+        &invalid_uvs,
+        &missing_uvs);
+
+    /* Add deformation modifier if necessary. */
+    blender::ed::curves::ensure_surface_deformation_node_exists(*C, curves_ob);
+
+    /* TODO: Not sure if I have to do id reference counting here. */
+    curves_id.surface = &new_surface_ob;
+    ED_object_parent_set(
+        op->reports, C, scene, &curves_ob, &new_surface_ob, PAR_OBJECT, false, true, nullptr);
+
+    DEG_id_tag_update(&curves_ob.id, ID_RECALC_TRANSFORM);
+    WM_event_add_notifier(C, NC_GEOM | ND_DATA, &curves_id);
+
+    /* Required for deformation. */
+    new_surface_ob.modifier_flag |= OB_MODIFIER_FLAG_ADD_REST_POSITION;
+    DEG_id_tag_update(&new_surface_ob.id, ID_RECALC_GEOMETRY);
+  }
+  CTX_DATA_END;
+
+  DEG_relations_tag_update(bmain);
+
+  return OPERATOR_FINISHED;
+}
+
+}  // namespace surface_set
+
+static void CURVES_OT_surface_set(wmOperatorType *ot)
+{
+  ot->name = "Set Curves Surface Object";
+  ot->idname = __func__;
+  ot->description = "Use the active object as surface for selected curves objects";
+
+  ot->exec = surface_set::surface_set_exec;
+  ot->poll = surface_set::surface_set_poll;
+
+  ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
+}
+
 }  // namespace blender::ed::curves
 
 void ED_operatortypes_curves()
@@ -955,4 +1037,5 @@ void ED_operatortypes_curves()
   WM_operatortype_append(CURVES_OT_set_selection_domain);
   WM_operatortype_append(SCULPT_CURVES_OT_select_all);
   WM_operatortype_append(CURVES_OT_disable_selection);
+  WM_operatortype_append(CURVES_OT_surface_set);
 }

source/blender/editors/include/ED_curves.h

@@ -29,6 +29,7 @@ bke::CurvesGeometry primitive_random_sphere(int curves_size, int points_per_curv
 bool selection_operator_poll(bContext *C);
 bool has_anything_selected(const Curves &curves_id);
 VectorSet<Curves *> get_unique_editable_curves(const bContext &C);
+void ensure_surface_deformation_node_exists(bContext &C, Object &curves_ob);
 
 }  // namespace blender::ed::curves
 #endif

source/blender/editors/object/object_add.cc

@@ -24,6 +24,7 @@
 #include "DNA_material_types.h"
 #include "DNA_mesh_types.h"
 #include "DNA_meta_types.h"
+#include "DNA_modifier_types.h"
 #include "DNA_object_fluidsim_types.h"
 #include "DNA_object_force_types.h"
 #include "DNA_object_types.h"
@@ -72,6 +73,7 @@
 #include "BKE_mesh.h"
 #include "BKE_mesh_runtime.h"
 #include "BKE_nla.h"
+#include "BKE_node.h"
 #include "BKE_object.h"
 #include "BKE_particle.h"
 #include "BKE_pointcloud.h"
@@ -114,6 +116,10 @@
 
 #include "object_intern.h"
 
+using blender::float3;
+using blender::float4x4;
+using blender::Vector;
+
 /* -------------------------------------------------------------------- */
 /** \name Local Enum Declarations
  * \{ */
@@ -2071,30 +2077,44 @@ void OBJECT_OT_curves_random_add(wmOperatorType *ot)
 
 static int object_curves_empty_hair_add_exec(bContext *C, wmOperator *op)
 {
+  Scene *scene = CTX_data_scene(C);
+
   ushort local_view_bits;
-  float loc[3], rot[3];
+  blender::float3 loc, rot;
   if (!ED_object_add_generic_get_opts(
           C, op, 'Z', loc, rot, nullptr, nullptr, &local_view_bits, nullptr)) {
     return OPERATOR_CANCELLED;
   }
 
   Object *surface_ob = CTX_data_active_object(C);
+  BLI_assert(surface_ob != nullptr);
 
-  Object *object = ED_object_add_type(C, OB_CURVES, nullptr, loc, rot, false, local_view_bits);
-  object->dtx |= OB_DRAWBOUNDOX; /* TODO: remove once there is actual drawing. */
+  Object *curves_ob = ED_object_add_type(C, OB_CURVES, nullptr, loc, rot, false, local_view_bits);
+  curves_ob->dtx |= OB_DRAWBOUNDOX; /* TODO: remove once there is actual drawing. */
 
-  if (surface_ob != nullptr && surface_ob->type == OB_MESH) {
-    Curves *curves_id = static_cast<Curves *>(object->data);
-    curves_id->surface = surface_ob;
-    id_us_plus(&surface_ob->id);
+  /* Set surface object. */
+  Curves *curves_id = static_cast<Curves *>(curves_ob->data);
+  curves_id->surface = surface_ob;
+  id_us_plus(&surface_ob->id);
 
-    Mesh *surface_mesh = static_cast<Mesh *>(surface_ob->data);
-    const char *uv_name = CustomData_get_active_layer_name(&surface_mesh->ldata, CD_MLOOPUV);
-    if (uv_name != nullptr) {
-      curves_id->surface_uv_map = BLI_strdup(uv_name);
-    }
+  /* Parent to surface object. */
+  ED_object_parent_set(
+      op->reports, C, scene, curves_ob, surface_ob, PAR_OBJECT, false, true, nullptr);
+
+  /* Decide which UV map to use for attachment. */
+  Mesh *surface_mesh = static_cast<Mesh *>(surface_ob->data);
+  const char *uv_name = CustomData_get_active_layer_name(&surface_mesh->ldata, CD_MLOOPUV);
+  if (uv_name != nullptr) {
+    curves_id->surface_uv_map = BLI_strdup(uv_name);
   }
 
+  /* Add deformation modifier. */
+  blender::ed::curves::ensure_surface_deformation_node_exists(*C, *curves_ob);
+
+  /* Make sure the surface object has a rest position attribute which is necessary for
+   * deformations. */
+  surface_ob->modifier_flag |= OB_MODIFIER_FLAG_ADD_REST_POSITION;
+
   return OPERATOR_FINISHED;
 }
 

source/blender/editors/object/object_relations.c

@@ -951,7 +951,7 @@ static int parent_set_invoke_menu(bContext *C, wmOperatorType *ot)
                  1);
 
   struct {
-    bool mesh, gpencil;
+    bool mesh, gpencil, curves;
   } has_children_of_type = {0};
 
   CTX_DATA_BEGIN (C, Object *, child, selected_editable_objects) {
@@ -964,6 +964,9 @@ static int parent_set_invoke_menu(bContext *C, wmOperatorType *ot)
     if (child->type == OB_GPENCIL) {
       has_children_of_type.gpencil = true;
     }
+    if (child->type == OB_CURVES) {
+      has_children_of_type.curves = true;
+    }
   }
   CTX_DATA_END;
 
@@ -987,6 +990,11 @@ static int parent_set_invoke_menu(bContext *C, wmOperatorType *ot)
   else if (parent->type == OB_LATTICE) {
     uiItemEnumO_ptr(layout, ot, NULL, 0, "type", PAR_LATTICE);
   }
+  else if (parent->type == OB_MESH) {
+    if (has_children_of_type.curves) {
+      uiItemO(layout, "Object (Attach Curves to Surface)", ICON_NONE, "CURVES_OT_surface_set");
+    }
+  }
 
   /* vertex parenting */
   if (OB_TYPE_SUPPORT_PARVERT(parent->type)) {

source/blender/makesdna/DNA_object_types.h

@@ -434,7 +434,10 @@ typedef struct Object {
   char empty_image_visibility_flag;
   char empty_image_depth;
   char empty_image_flag;
-  char _pad8[5];
+
+  /** ObjectModifierFlag */
+  uint8_t modifier_flag;
+  char _pad8[4];
 
   struct PreviewImage *preview;
 
@@ -788,6 +791,10 @@ enum {
   OB_EMPTY_IMAGE_USE_ALPHA_BLEND = 1 << 0,
 };
 
+typedef enum ObjectModifierFlag {
+  OB_MODIFIER_FLAG_ADD_REST_POSITION = 1 << 0,
+} ObjectModifierFlag;
+
 #define MAX_DUPLI_RECUR 8
 
 #ifdef __cplusplus

source/blender/makesrna/intern/rna_object.c

@@ -3579,6 +3579,14 @@ static void rna_def_object(BlenderRNA *brna)
   RNA_def_property_ui_text(prop, "Empty Image Side", "Show front/back side");
   RNA_def_property_update(prop, NC_OBJECT | ND_DRAW, NULL);
 
+  prop = RNA_def_property(srna, "add_rest_position_attribute", PROP_BOOLEAN, PROP_NONE);
+  RNA_def_property_boolean_sdna(prop, NULL, "modifier_flag", OB_MODIFIER_FLAG_ADD_REST_POSITION);
+  RNA_def_property_ui_text(prop,
+                           "Add Rest Position",
+                           "Add a \"rest_position\" attribute that is a copy of the position "
+                           "attribute before shape keys and modifiers are evaluated");
+  RNA_def_property_update(prop, NC_OBJECT | ND_DRAW, "rna_Object_internal_update_data");
+
   /* render */
   prop = RNA_def_property(srna, "pass_index", PROP_INT, PROP_UNSIGNED);
   RNA_def_property_int_sdna(prop, NULL, "index");

source/blender/modifiers/intern/MOD_nodes.cc

@@ -21,6 +21,7 @@
 #include "BLI_utildefines.h"
 
 #include "DNA_collection_types.h"
+#include "DNA_curves_types.h"
 #include "DNA_defaults.h"
 #include "DNA_material_types.h"
 #include "DNA_mesh_types.h"
@@ -190,6 +191,10 @@ static bool node_needs_own_transform_relation(const bNode &node)
     return storage.transform_space == GEO_NODE_TRANSFORM_SPACE_RELATIVE;
   }
 
+  if (node.type == GEO_NODE_DEFORM_CURVES_ON_SURFACE) {
+    return true;
+  }
+
   return false;
 }
 
@@ -269,6 +274,14 @@ static void updateDepsgraph(ModifierData *md, const ModifierUpdateDepsgraphConte
   Set<ID *> used_ids;
   find_used_ids_from_settings(nmd->settings, used_ids);
   process_nodes_for_depsgraph(*nmd->node_group, used_ids, needs_own_transform_relation);
+
+  if (ctx->object->type == OB_CURVES) {
+    Curves *curves_id = static_cast<Curves *>(ctx->object->data);
+    if (curves_id->surface != nullptr) {
+      used_ids.add(&curves_id->surface->id);
+    }
+  }
+
   for (ID *id : used_ids) {
     switch ((ID_Type)GS(id->name)) {
       case ID_OB: {

source/blender/nodes/NOD_geometry.h

@@ -47,6 +47,7 @@ void register_node_type_geo_curve_subdivide(void);
 void register_node_type_geo_curve_to_mesh(void);
 void register_node_type_geo_curve_to_points(void);
 void register_node_type_geo_curve_trim(void);
+void register_node_type_geo_deform_curves_on_surface(void);
 void register_node_type_geo_delete_geometry(void);
 void register_node_type_geo_duplicate_elements(void);
 void register_node_type_geo_distribute_points_on_faces(void);

source/blender/nodes/NOD_static_types.h

@@ -301,6 +301,7 @@ DefNode(GeometryNode, GEO_NODE_CURVE_SPLINE_PARAMETER, 0, "SPLINE_PARAMETER", Sp
 DefNode(GeometryNode, GEO_NODE_CURVE_SPLINE_TYPE, def_geo_curve_spline_type, "CURVE_SPLINE_TYPE", CurveSplineType, "Set Spline Type", "")
 DefNode(GeometryNode, GEO_NODE_CURVE_TO_MESH, 0, "CURVE_TO_MESH", CurveToMesh, "Curve to Mesh", "")
 DefNode(GeometryNode, GEO_NODE_CURVE_TO_POINTS, def_geo_curve_to_points, "CURVE_TO_POINTS", CurveToPoints, "Curve to Points", "")
+DefNode(GeometryNode, GEO_NODE_DEFORM_CURVES_ON_SURFACE, 0, "DEFORM_CURVES_ON_SURFACE", DeformCurvesOnSurface, "Deform Curves on Surface", "")
 DefNode(GeometryNode, GEO_NODE_DELETE_GEOMETRY, def_geo_delete_geometry, "DELETE_GEOMETRY", DeleteGeometry, "Delete Geometry", "")
 DefNode(GeometryNode, GEO_NODE_DUPLICATE_ELEMENTS, def_geo_duplicate_elements, "DUPLICATE_ELEMENTS", DuplicateElements, "Duplicate Elements", "")
 DefNode(GeometryNode, GEO_NODE_DISTRIBUTE_POINTS_ON_FACES, def_geo_distribute_points_on_faces, "DISTRIBUTE_POINTS_ON_FACES", DistributePointsOnFaces, "Distribute Points on Faces", "")

source/blender/nodes/geometry/CMakeLists.txt

@@ -57,6 +57,7 @@ set(SRC
   nodes/node_geo_curve_to_mesh.cc
   nodes/node_geo_curve_to_points.cc
   nodes/node_geo_curve_trim.cc
+  nodes/node_geo_deform_curves_with_surface.cc
   nodes/node_geo_delete_geometry.cc
   nodes/node_geo_distribute_points_on_faces.cc
   nodes/node_geo_dual_mesh.cc

source/blender/nodes/geometry/nodes/node_geo_deform_curves_with_surface.cc

@@ -0,0 +1,345 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#include "BKE_attribute_math.hh"
+#include "BKE_curves.hh"
+#include "BKE_editmesh.h"
+#include "BKE_lib_id.h"
+#include "BKE_mesh.h"
+#include "BKE_mesh_runtime.h"
+#include "BKE_mesh_wrapper.h"
+#include "BKE_modifier.h"
+#include "BKE_type_conversions.hh"
+
+#include "BLI_float3x3.hh"
+#include "BLI_task.hh"
+
+#include "UI_interface.h"
+#include "UI_resources.h"
+
+#include "DNA_mesh_types.h"
+#include "DNA_meshdata_types.h"
+
+#include "NOD_socket_search_link.hh"
+
+#include "GEO_reverse_uv_sampler.hh"
+
+#include "DEG_depsgraph_query.h"
+
+#include "node_geometry_util.hh"
+
+namespace blender::nodes::node_geo_deform_curves_with_surface_cc {
+
+using attribute_math::mix3;
+using bke::CurvesGeometry;
+using geometry::ReverseUVSampler;
+
+NODE_STORAGE_FUNCS(NodeGeometryCurveTrim)
+
+static void node_declare(NodeDeclarationBuilder &b)
+{
+  b.add_input<decl::Geometry>(N_("Curves")).supported_type(GEO_COMPONENT_TYPE_CURVE);
+  b.add_output<decl::Geometry>(N_("Curves"));
+}
+
+static void deform_curves(CurvesGeometry &curves,
+                          const Mesh &surface_mesh_old,
+                          const Mesh &surface_mesh_new,
+                          const Span<float2> curve_attachment_uvs,
+                          const ReverseUVSampler &reverse_uv_sampler_old,
+                          const ReverseUVSampler &reverse_uv_sampler_new,
+                          const Span<float3> corner_normals_old,
+                          const Span<float3> corner_normals_new,
+                          const Span<float3> rest_positions,
+                          const float4x4 &surface_to_curves,
+                          std::atomic<int> &r_invalid_uv_count)
+{
+  /* Find attachment points on old and new mesh. */
+  const int curves_num = curves.curves_num();
+  Array<ReverseUVSampler::Result> surface_samples_old(curves_num);
+  Array<ReverseUVSampler::Result> surface_samples_new(curves_num);
+  threading::parallel_invoke(
+      [&]() { reverse_uv_sampler_old.sample_many(curve_attachment_uvs, surface_samples_old); },
+      [&]() { reverse_uv_sampler_new.sample_many(curve_attachment_uvs, surface_samples_new); });
+
+  MutableSpan<float3> positions = curves.positions_for_write();
+
+  const float4x4 curves_to_surface = surface_to_curves.inverted();
+
+  threading::parallel_for(curves.curves_range(), 256, [&](const IndexRange range) {
+    for (const int curve_i : range) {
+      const ReverseUVSampler::Result &surface_sample_old = surface_samples_old[curve_i];
+      if (surface_sample_old.type != ReverseUVSampler::ResultType::Ok) {
+        r_invalid_uv_count++;
+        continue;
+      }
+      const ReverseUVSampler::Result &surface_sample_new = surface_samples_new[curve_i];
+      if (surface_sample_new.type != ReverseUVSampler::ResultType::Ok) {
+        r_invalid_uv_count++;
+        continue;
+      }
+
+      const MLoopTri &looptri_old = *surface_sample_old.looptri;
+      const MLoopTri &looptri_new = *surface_sample_new.looptri;
+      const float3 &bary_weights_old = surface_sample_old.bary_weights;
+      const float3 &bary_weights_new = surface_sample_new.bary_weights;
+
+      const int corner_0_old = looptri_old.tri[0];
+      const int corner_1_old = looptri_old.tri[1];
+      const int corner_2_old = looptri_old.tri[2];
+
+      const int corner_0_new = looptri_new.tri[0];
+      const int corner_1_new = looptri_new.tri[1];
+      const int corner_2_new = looptri_new.tri[2];
+
+      const int vert_0_old = surface_mesh_old.mloop[corner_0_old].v;
+      const int vert_1_old = surface_mesh_old.mloop[corner_1_old].v;
+      const int vert_2_old = surface_mesh_old.mloop[corner_2_old].v;
+
+      const int vert_0_new = surface_mesh_new.mloop[corner_0_new].v;
+      const int vert_1_new = surface_mesh_new.mloop[corner_1_new].v;
+      const int vert_2_new = surface_mesh_new.mloop[corner_2_new].v;
+
+      const float3 &normal_0_old = corner_normals_old[corner_0_old];
+      const float3 &normal_1_old = corner_normals_old[corner_1_old];
+      const float3 &normal_2_old = corner_normals_old[corner_2_old];
+      const float3 normal_old = math::normalize(
+          mix3(bary_weights_old, normal_0_old, normal_1_old, normal_2_old));
+
+      const float3 &normal_0_new = corner_normals_new[corner_0_new];
+      const float3 &normal_1_new = corner_normals_new[corner_1_new];
+      const float3 &normal_2_new = corner_normals_new[corner_2_new];
+      const float3 normal_new = math::normalize(
+          mix3(bary_weights_new, normal_0_new, normal_1_new, normal_2_new));
+
+      const float3 &pos_0_old = surface_mesh_old.mvert[vert_0_old].co;
+      const float3 &pos_1_old = surface_mesh_old.mvert[vert_1_old].co;
+      const float3 &pos_2_old = surface_mesh_old.mvert[vert_2_old].co;
+      const float3 pos_old = mix3(bary_weights_old, pos_0_old, pos_1_old, pos_2_old);
+
+      const float3 &pos_0_new = surface_mesh_new.mvert[vert_0_new].co;
+      const float3 &pos_1_new = surface_mesh_new.mvert[vert_1_new].co;
+      const float3 &pos_2_new = surface_mesh_new.mvert[vert_2_new].co;
+      const float3 pos_new = mix3(bary_weights_new, pos_0_new, pos_1_new, pos_2_new);
+
+      /* The translation is just the difference between the old and new position on the surface. */
+      const float3 translation = pos_new - pos_old;
+
+      const float3 &rest_pos_0 = rest_positions[vert_0_new];
+      const float3 &rest_pos_1 = rest_positions[vert_1_new];
+
+      /* The tangent reference direction is used to determine the rotation of the surface point
+       * around its normal axis. It's important that the old and new tangent reference are computed
+       * in a consistent way. If the surface has not been rotated, the old and new tangent
+       * reference have to have the same direction. For that reason, the old tangent reference is
+       * computed based on the rest position attribute instead of positions on the old mesh. This
+       * way the old and new tangent reference use the same topology.
+       *
+       * TODO: Figure out if this can be smoothly interpolated across the surface as well.
+       * Currently, this is a source of discontinuity in the deformation, because the vector
+       * changes intantly from one triangle to the next. */
+      const float3 tangent_reference_dir_old = rest_pos_1 - rest_pos_0;
+      const float3 tangent_reference_dir_new = pos_1_new - pos_0_new;
+
+      /* Compute first local tangent based on the (potentially smoothed) normal and the tangent
+       * reference. */
+      const float3 tangent_x_old = math::normalize(
+          math::cross(normal_old, tangent_reference_dir_old));
+      const float3 tangent_x_new = math::normalize(
+          math::cross(normal_new, tangent_reference_dir_new));
+
+      /* The second tangent defined by the normal and first tangent. */
+      const float3 tangent_y_old = math::normalize(math::cross(normal_old, tangent_x_old));
+      const float3 tangent_y_new = math::normalize(math::cross(normal_new, tangent_x_new));
+
+      /* Construct rotation matrix that encodes the orientation of the old surface position. */
+      float3x3 rotation_old;
+      copy_v3_v3(rotation_old.values[0], tangent_x_old);
+      copy_v3_v3(rotation_old.values[1], tangent_y_old);
+      copy_v3_v3(rotation_old.values[2], normal_old);
+
+      /* Construct rotation matrix that encodes the orientation of the new surface position. */
+      float3x3 rotation_new;
+      copy_v3_v3(rotation_new.values[0], tangent_x_new);
+      copy_v3_v3(rotation_new.values[1], tangent_y_new);
+      copy_v3_v3(rotation_new.values[2], normal_new);
+
+      /* Can use transpose instead of inverse because the matrix is orthonormal. */
+      const float3x3 rotation_old_inv = rotation_old.transposed();
+
+      /* Compute a rotation matrix that rotates points from the old to the new surface
+       * orientation. */
+      const float3x3 rotation = rotation_new * rotation_old_inv;
+      float4x4 rotation_4x4;
+      copy_m4_m3(rotation_4x4.values, rotation.values);
+
+      /* Construction transformation matrix for this surface position that includes rotation and
+       * translation. */
+      float4x4 surface_transform = float4x4::identity();
+      sub_v3_v3(surface_transform.values[3], pos_old);
+      mul_m4_m4_pre(surface_transform.values, rotation_4x4.values);
+      add_v3_v3(surface_transform.values[3], translation);
+      add_v3_v3(surface_transform.values[3], pos_old);
+
+      /* Change the basis of the transformation so to that it can be applied in the local space of
+       * the curves. */
+      const float4x4 curve_transform = surface_to_curves * surface_transform * curves_to_surface;
+
+      /* Actually transform all points. */
+      const IndexRange points = curves.points_for_curve(curve_i);
+      for (const int point_i : points) {
+        const float3 old_point_pos = positions[point_i];
+        const float3 new_point_pos = curve_transform * old_point_pos;
+        positions[point_i] = new_point_pos;
+      }
+    }
+  });
+}
+
+static void node_geo_exec(GeoNodeExecParams params)
+{
+  GeometrySet curves_geometry = params.extract_input<GeometrySet>("Curves");
+
+  Mesh *surface_mesh_orig = nullptr;
+  bool free_suface_mesh_orig = false;
+
+  auto pass_through_input = [&]() {
+    params.set_output("Curves", std::move(curves_geometry));
+    if (free_suface_mesh_orig) {
+      BKE_id_free(nullptr, surface_mesh_orig);
+    }
+  };
+
+  const Object *self_ob_eval = params.self_object();
+  if (self_ob_eval == nullptr || self_ob_eval->type != OB_CURVES) {
+    pass_through_input();
+    return;
+  }
+  const Curves *self_curves_eval = static_cast<const Curves *>(self_ob_eval->data);
+  Object *surface_ob_eval = self_curves_eval->surface;
+  const StringRef uv_map_name = self_curves_eval->surface_uv_map;
+  const StringRef rest_position_name = "rest_position";
+
+  if (!curves_geometry.has_curves()) {
+    pass_through_input();
+    return;
+  }
+  if (surface_ob_eval == nullptr || surface_ob_eval->type != OB_MESH) {
+    pass_through_input();
+    return;
+  }
+  Object *surface_ob_orig = DEG_get_original_object(surface_ob_eval);
+  Mesh &surface_object_data = *static_cast<Mesh *>(surface_ob_orig->data);
+
+  if (BMEditMesh *em = surface_object_data.edit_mesh) {
+    surface_mesh_orig = BKE_mesh_from_bmesh_for_eval_nomain(em->bm, NULL, &surface_object_data);
+    free_suface_mesh_orig = true;
+  }
+  else {
+    surface_mesh_orig = &surface_object_data;
+  }
+  Mesh *surface_mesh_eval = BKE_modifier_get_evaluated_mesh_from_evaluated_object(surface_ob_eval,
+                                                                                  false);
+  if (surface_mesh_eval == nullptr) {
+    pass_through_input();
+    return;
+  }
+
+  BKE_mesh_wrapper_ensure_mdata(surface_mesh_eval);
+
+  MeshComponent mesh_eval;
+  mesh_eval.replace(surface_mesh_eval, GeometryOwnershipType::ReadOnly);
+  MeshComponent mesh_orig;
+  mesh_orig.replace(surface_mesh_orig, GeometryOwnershipType::ReadOnly);
+
+  Curves &curves_id = *curves_geometry.get_curves_for_write();
+  CurvesGeometry &curves = CurvesGeometry::wrap(curves_id.geometry);
+
+  if (!mesh_orig.attribute_exists(uv_map_name)) {
+    pass_through_input();
+    return;
+  }
+  if (!mesh_eval.attribute_exists(uv_map_name)) {
+    pass_through_input();
+    return;
+  }
+  if (!mesh_eval.attribute_exists(rest_position_name)) {
+    pass_through_input();
+    return;
+  }
+  if (curves.surface_uv_coords().is_empty()) {
+    pass_through_input();
+    return;
+  }
+  const VArraySpan<float2> uv_map_orig = mesh_orig.attribute_get_for_read<float2>(
+      uv_map_name, ATTR_DOMAIN_CORNER, {0.0f, 0.0f});
+  const VArraySpan<float2> uv_map_eval = mesh_eval.attribute_get_for_read<float2>(
+      uv_map_name, ATTR_DOMAIN_CORNER, {0.0f, 0.0f});
+  const VArraySpan<float3> rest_positions = mesh_eval.attribute_get_for_read<float3>(
+      rest_position_name, ATTR_DOMAIN_POINT, {0.0f, 0.0f, 0.0f});
+  const Span<float2> surface_uv_coords = curves.surface_uv_coords();
+
+  const Span<MLoopTri> looptris_orig{BKE_mesh_runtime_looptri_ensure(surface_mesh_orig),
+                                     BKE_mesh_runtime_looptri_len(surface_mesh_orig)};
+  const Span<MLoopTri> looptris_eval{BKE_mesh_runtime_looptri_ensure(surface_mesh_eval),
+                                     BKE_mesh_runtime_looptri_len(surface_mesh_eval)};
+  const ReverseUVSampler reverse_uv_sampler_orig{uv_map_orig, looptris_orig};
+  const ReverseUVSampler reverse_uv_sampler_eval{uv_map_eval, looptris_eval};
+
+  /* Retrieve face corner normals from each mesh. It's necessary to use face corner normals
+   * because face normals or vertex normals may lose information (custom normals, auto smooth) in
+   * some cases. It isn't yet possible to retrieve lazily calculated face corner normals from a
+   * const mesh, so they are calculated here every time. */
+  Array<float3> corner_normals_orig(surface_mesh_orig->totloop);
+  Array<float3> corner_normals_eval(surface_mesh_eval->totloop);
+  BKE_mesh_calc_normals_split_ex(
+      surface_mesh_orig, nullptr, reinterpret_cast<float(*)[3]>(corner_normals_orig.data()));
+  BKE_mesh_calc_normals_split_ex(
+      surface_mesh_eval, nullptr, reinterpret_cast<float(*)[3]>(corner_normals_eval.data()));
+
+  std::atomic<int> invalid_uv_count = 0;
+
+  const bke::CurvesSurfaceTransforms transforms{*self_ob_eval, surface_ob_eval};
+
+  deform_curves(curves,
+                *surface_mesh_orig,
+                *surface_mesh_eval,
+                surface_uv_coords,
+                reverse_uv_sampler_orig,
+                reverse_uv_sampler_eval,
+                corner_normals_orig,
+                corner_normals_eval,
+                rest_positions,
+                transforms.surface_to_curves,
+                invalid_uv_count);
+
+  curves.tag_positions_changed();
+
+  if (invalid_uv_count) {
+    char *error = BLI_sprintfN(
+        TIP_("Invalid surface attachment UV coordinates found on %d curves"),
+        invalid_uv_count.load());
+    params.error_message_add(NodeWarningType::Warning, error);
+    MEM_freeN(error);
+  }
+
+  if (free_suface_mesh_orig) {
+    BKE_id_free(nullptr, surface_mesh_orig);
+  }
+
+  params.set_output("Curves", curves_geometry);
+}
+
+}  // namespace blender::nodes::node_geo_deform_curves_with_surface_cc
+
+void register_node_type_geo_deform_curves_on_surface()
+{
+  namespace file_ns = blender::nodes::node_geo_deform_curves_with_surface_cc;
+
+  static bNodeType ntype;
+  geo_node_type_base(
+      &ntype, GEO_NODE_DEFORM_CURVES_ON_SURFACE, "Deform Curves on Surface", NODE_CLASS_GEOMETRY);
+  ntype.geometry_node_execute = file_ns::node_geo_exec;
+  ntype.declare = file_ns::node_declare;
+  node_type_size(&ntype, 170, 120, 700);
+  nodeRegisterType(&ntype);
+}