Overlap point position with rays inside of Raycast manager

Fix unstability of text origin position when start use surface

src/slic3r/GUI/Gizmos/GLGizmoEmboss.cpp

@@ -2980,11 +2980,6 @@ std::optional<Vec3d> priv::calc_surface_offset(const ModelVolume &volume, Raycas
 
     // ray in direction of text projection(from volume zero to z-dir)
     std::optional<RaycastManager::Hit> hit_opt = raycast_manager.unproject(point, direction, &cond);
-    // start point lay on surface could appear slightly behind surface
-    std::optional<RaycastManager::Hit> hit_opt_opposit = raycast_manager.unproject(point, -direction, &cond);
-    if (!hit_opt.has_value() || 
-        (hit_opt_opposit.has_value() && hit_opt->squared_distance > hit_opt_opposit->squared_distance))
-        hit_opt = hit_opt_opposit;
 
     // Try to find closest point when no hit object in emboss direction
     if (!hit_opt.has_value())

src/slic3r/Utils/RaycastManager.cpp

@@ -124,7 +124,15 @@ std::optional<RaycastManager::Hit> RaycastManager::unproject(const Vec3d &point,
         Transform3d tr_inv = transformation.inverse();
         Vec3d mesh_point = tr_inv * point;
         Vec3d mesh_direction = tr_inv.linear() * direction;
-        std::vector<AABBMesh::hit_result> hits = mesh.query_ray_hits(mesh_point, mesh_direction);
+
+        // Need for detect that actual point position is on correct place
+        Vec3d point_positive = mesh_point - mesh_direction;
+        Vec3d point_negative = mesh_point + mesh_direction;
+
+        // Throw ray to both directions of ray
+        std::vector<AABBMesh::hit_result> hits = mesh.query_ray_hits(point_positive, mesh_direction);
+        std::vector<AABBMesh::hit_result> hits_neg = mesh.query_ray_hits(point_negative, -mesh_direction);
+        hits.insert(hits.end(), std::make_move_iterator(hits_neg.begin()), std::make_move_iterator(hits_neg.end()));
         for (const AABBMesh::hit_result &hit : hits) { 
             double squared_distance = (mesh_point - hit.position()).squaredNorm();
             if (closest.has_value() &&

src/slic3r/Utils/RaycastManager.hpp

@@ -106,6 +106,7 @@ public:
 
     /// <summary>
     /// Unproject Ray(point direction) on mesh by MeshRaycasters
+    /// NOTE: It inspect also oposit direction of ray !!
     /// </summary>
     /// <param name="point">Start point for ray</param>
     /// <param name="direction">Direction of ray</param>