Curves: add warning when invalid uv map is used when adding curves

UV maps that are used for surface attachment must not have overlapping
uv islands, because then the same uv coordinate would correspond to
multiple surface positions.

Ref T99936.

6 files changed, 33 insertions, 4 deletions

diff --git a/source/blender/editors/sculpt_paint/curves_sculpt_add.cc b/source/blender/editors/sculpt_paint/curves_sculpt_add.cc
index 2757701675b..6c693376ad3 100644
--- a/source/blender/editors/sculpt_paint/curves_sculpt_add.cc
+++ b/source/blender/editors/sculpt_paint/curves_sculpt_add.cc
@@ -231,7 +231,12 @@ struct AddOperationExecutor {
       add_inputs.old_roots_kdtree = self_->curve_roots_kdtree_;
     }
 
-    geometry::add_curves_on_mesh(*curves_orig_, add_inputs);
+    const geometry::AddCurvesOnMeshOutputs add_outputs = geometry::add_curves_on_mesh(
+        *curves_orig_, add_inputs);
+
+    if (add_outputs.uv_error) {
+      report_invalid_uv_map(stroke_extension.reports);
+    }
 
     DEG_id_tag_update(&curves_id_orig_->id, ID_RECALC_GEOMETRY);
     WM_main_add_notifier(NC_GEOM | ND_DATA, &curves_id_orig_->id);
diff --git a/source/blender/editors/sculpt_paint/curves_sculpt_brush.cc b/source/blender/editors/sculpt_paint/curves_sculpt_brush.cc
index 9803c6fdcc6..a180a232189 100644
--- a/source/blender/editors/sculpt_paint/curves_sculpt_brush.cc
+++ b/source/blender/editors/sculpt_paint/curves_sculpt_brush.cc
@@ -408,4 +408,9 @@ void report_missing_uv_map_on_evaluated_surface(ReportList *reports)
       reports, RPT_WARNING, TIP_("Missing UV map for attaching curves on evaluated surface"));
 }
 
+void report_invalid_uv_map(ReportList *reports)
+{
+  BKE_report(reports, RPT_WARNING, TIP_("Invalid UV map: UV islands must not overlap"));
+}
+
 }  // namespace blender::ed::sculpt_paint
diff --git a/source/blender/editors/sculpt_paint/curves_sculpt_density.cc b/source/blender/editors/sculpt_paint/curves_sculpt_density.cc
index b07f5c74055..6ad3d0e4aad 100644
--- a/source/blender/editors/sculpt_paint/curves_sculpt_density.cc
+++ b/source/blender/editors/sculpt_paint/curves_sculpt_density.cc
@@ -277,7 +277,12 @@ struct DensityAddOperationExecutor {
     add_inputs.reverse_uv_sampler = &reverse_uv_sampler;
     add_inputs.old_roots_kdtree = self_->original_curve_roots_kdtree_;
 
-    geometry::add_curves_on_mesh(*curves_orig_, add_inputs);
+    const geometry::AddCurvesOnMeshOutputs add_outputs = geometry::add_curves_on_mesh(
+        *curves_orig_, add_inputs);
+
+    if (add_outputs.uv_error) {
+      report_invalid_uv_map(stroke_extension.reports);
+    }
 
     DEG_id_tag_update(&curves_id_orig_->id, ID_RECALC_GEOMETRY);
     WM_main_add_notifier(NC_GEOM | ND_DATA, &curves_id_orig_->id);
diff --git a/source/blender/editors/sculpt_paint/curves_sculpt_intern.hh b/source/blender/editors/sculpt_paint/curves_sculpt_intern.hh
index 4bb00a7d621..7d40ed80a65 100644
--- a/source/blender/editors/sculpt_paint/curves_sculpt_intern.hh
+++ b/source/blender/editors/sculpt_paint/curves_sculpt_intern.hh
@@ -131,5 +131,6 @@ float transform_brush_radius(const float4x4 &transform,
 void report_missing_surface(ReportList *reports);
 void report_missing_uv_map_on_original_surface(ReportList *reports);
 void report_missing_uv_map_on_evaluated_surface(ReportList *reports);
+void report_invalid_uv_map(ReportList *reports);
 
 }  // namespace blender::ed::sculpt_paint
diff --git a/source/blender/geometry/GEO_add_curves_on_mesh.hh b/source/blender/geometry/GEO_add_curves_on_mesh.hh
index 68c8dc5b76b..2d2ba89a18f 100644
--- a/source/blender/geometry/GEO_add_curves_on_mesh.hh
+++ b/source/blender/geometry/GEO_add_curves_on_mesh.hh
@@ -40,12 +40,19 @@ struct AddCurvesOnMeshInputs {
    * interpolation is used.
    */
   KDTree_3d *old_roots_kdtree = nullptr;
+
+  bool r_uv_error = false;
+};
+
+struct AddCurvesOnMeshOutputs {
+  bool uv_error = false;
 };
 
 /**
  * Generate new curves on a mesh surface with the given inputs. Existing curves stay intact.
  */
-void add_curves_on_mesh(bke::CurvesGeometry &curves, const AddCurvesOnMeshInputs &inputs);
+AddCurvesOnMeshOutputs add_curves_on_mesh(bke::CurvesGeometry &curves,
+                                          const AddCurvesOnMeshInputs &inputs);
 
 float3 compute_surface_point_normal(const MLoopTri &looptri,
                                     const float3 &bary_coord,
diff --git a/source/blender/geometry/intern/add_curves_on_mesh.cc b/source/blender/geometry/intern/add_curves_on_mesh.cc
index aa04cedb5c5..7184d774a22 100644
--- a/source/blender/geometry/intern/add_curves_on_mesh.cc
+++ b/source/blender/geometry/intern/add_curves_on_mesh.cc
@@ -229,8 +229,11 @@ static void interpolate_position_with_interpolation(CurvesGeometry &curves,
   });
 }
 
-void add_curves_on_mesh(CurvesGeometry &curves, const AddCurvesOnMeshInputs &inputs)
+AddCurvesOnMeshOutputs add_curves_on_mesh(CurvesGeometry &curves,
+                                          const AddCurvesOnMeshInputs &inputs)
 {
+  AddCurvesOnMeshOutputs outputs;
+
   const bool use_interpolation = inputs.interpolate_length || inputs.interpolate_point_count ||
                                  inputs.interpolate_shape;
 
@@ -244,6 +247,7 @@ void add_curves_on_mesh(CurvesGeometry &curves, const AddCurvesOnMeshInputs &inp
     const float2 &uv = inputs.uvs[i];
     const ReverseUVSampler::Result result = inputs.reverse_uv_sampler->sample(uv);
     if (result.type != ReverseUVSampler::ResultType::Ok) {
+      outputs.uv_error = true;
       continue;
     }
     const MLoopTri &looptri = *result.looptri;
@@ -365,6 +369,8 @@ void add_curves_on_mesh(CurvesGeometry &curves, const AddCurvesOnMeshInputs &inp
   MutableSpan<int8_t> types_span = curves.curve_types_for_write();
   types_span.drop_front(old_curves_num).fill(CURVE_TYPE_CATMULL_ROM);
   curves.update_curve_types();
+
+  return outputs;
 }
 
 }  // namespace blender::geometry