USD: Add support for Text objects during export

Similar to the existing meta-ball export, and the other exporters,
convert Text objects to meshes for export.

Ref #138883

Pull Request: https://projects.blender.org/blender/blender/pulls/138903

source/blender/io/common/intern/abstract_hierarchy_iterator.cc

@@ -811,8 +811,8 @@ bool AbstractHierarchyIterator::mark_as_weak_export(const Object * /*object*/) c
 bool AbstractHierarchyIterator::should_visit_dupli_object(const DupliObject *dupli_object) const
 {
   /* Do not visit dupli objects if their `no_draw` flag is set (things like custom bone shapes) or
-   * if they are meta-balls. */
-  if (dupli_object->no_draw || dupli_object->ob->type == OB_MBALL) {
+   * if they are meta-balls / text objects. */
+  if (dupli_object->no_draw || ELEM(dupli_object->ob->type, OB_MBALL, OB_FONT)) {
     return false;
   }
 

source/blender/io/usd/CMakeLists.txt

@@ -84,6 +84,7 @@ set(SRC
   intern/usd_writer_mesh.cc
   intern/usd_writer_metaball.cc
   intern/usd_writer_points.cc
+  intern/usd_writer_text.cc
   intern/usd_writer_transform.cc
   intern/usd_writer_volume.cc
 
@@ -133,6 +134,7 @@ set(SRC
   intern/usd_writer_mesh.hh
   intern/usd_writer_metaball.hh
   intern/usd_writer_points.hh
+  intern/usd_writer_text.hh
   intern/usd_writer_transform.hh
   intern/usd_writer_volume.hh
 

source/blender/io/usd/intern/usd_hierarchy_iterator.cc

@@ -18,6 +18,7 @@
 #include "usd_writer_mesh.hh"
 #include "usd_writer_metaball.hh"
 #include "usd_writer_points.hh"
+#include "usd_writer_text.hh"
 #include "usd_writer_transform.hh"
 #include "usd_writer_volume.hh"
 
@@ -52,6 +53,7 @@ bool USDHierarchyIterator::mark_as_weak_export(const Object *object) const
       return false;
     case OB_MESH:
     case OB_MBALL:
+    case OB_FONT:
       return !params_.export_meshes;
     case OB_CAMERA:
       return !params_.export_cameras;
@@ -174,6 +176,9 @@ AbstractHierarchyWriter *USDHierarchyIterator::create_data_writer(const Hierarch
     case OB_MBALL:
       data_writer = new USDMetaballWriter(usd_export_context);
       break;
+    case OB_FONT:
+      data_writer = new USDTextWriter(usd_export_context);
+      break;
     case OB_CURVES_LEGACY:
     case OB_CURVES:
       if (usd_export_context.export_params.export_curves) {
@@ -210,7 +215,6 @@ AbstractHierarchyWriter *USDHierarchyIterator::create_data_writer(const Hierarch
 
     case OB_EMPTY:
     case OB_SURF:
-    case OB_FONT:
     case OB_SPEAKER:
     case OB_LIGHTPROBE:
     case OB_LATTICE:

source/blender/io/usd/intern/usd_writer_text.cc

@@ -0,0 +1,34 @@
+/* SPDX-FileCopyrightText: 2025 Blender Authors
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later */
+#include "usd_writer_text.hh"
+#include "usd_exporter_context.hh"
+
+#include "BKE_lib_id.hh"
+#include "BKE_mesh.hh"
+#include "BKE_object.hh"
+
+#include "DNA_mesh_types.h"
+
+namespace blender::io::usd {
+
+USDTextWriter::USDTextWriter(const USDExporterContext &ctx) : USDGenericMeshWriter(ctx) {}
+
+Mesh *USDTextWriter::get_export_mesh(Object *object_eval, bool &r_needsfree)
+{
+  Mesh *mesh_eval = BKE_object_get_evaluated_mesh(object_eval);
+  if (mesh_eval != nullptr) {
+    /* Mesh_eval only exists when generative modifiers are in use. */
+    r_needsfree = false;
+    return mesh_eval;
+  }
+  r_needsfree = true;
+  return BKE_mesh_new_from_object(usd_export_context_.depsgraph, object_eval, false, false, true);
+}
+
+void USDTextWriter::free_export_mesh(Mesh *mesh)
+{
+  BKE_id_free(nullptr, mesh);
+}
+
+}  // namespace blender::io::usd

source/blender/io/usd/intern/usd_writer_text.hh

@@ -0,0 +1,22 @@
+/* SPDX-FileCopyrightText: 2025 Blender Authors
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later */
+#pragma once
+
+#include "usd_writer_mesh.hh"
+
+struct Mesh;
+struct Object;
+
+namespace blender::io::usd {
+
+class USDTextWriter : public USDGenericMeshWriter {
+ public:
+  USDTextWriter(const USDExporterContext &ctx);
+
+ protected:
+  Mesh *get_export_mesh(Object *object_eval, bool &r_needsfree) override;
+  void free_export_mesh(Mesh *mesh) override;
+};
+
+}  // namespace blender::io::usd

tests/python/bl_usd_export_test.py

@@ -975,6 +975,66 @@ class USDExportTest(AbstractUSDTest):
         weight_samples = anim.GetBlendShapeWeightsAttr().GetTimeSamples()
         self.assertEqual(weight_samples, [1.0, 2.0, 3.0, 4.0, 5.0])
 
+    def test_export_text(self):
+        """Test various forms of Text/Font export."""
+
+        bpy.ops.wm.open_mainfile(filepath=str(self.testdir / "usd_text_test.blend"))
+
+        export_path = str(self.tempdir / "usd_text_test.usda")
+        self.export_and_validate(filepath=export_path, export_animation=True, evaluation_mode="RENDER")
+
+        stats = UsdUtils.ComputeUsdStageStats(export_path)
+        stage = Usd.Stage.Open(export_path)
+
+        # There should be 4 meshes in the output
+        self.assertEqual(stats['primary']['primCountsByType']['Mesh'], 4)
+
+        bboxcache_frame1 = UsdGeom.BBoxCache(1.0, [UsdGeom.Tokens.default_])
+        bboxcache_frame5 = UsdGeom.BBoxCache(5.0, [UsdGeom.Tokens.default_])
+
+        # Static, flat, text
+        mesh = UsdGeom.Mesh(stage.GetPrimAtPath("/root/static/static"))
+        bounds1 = bboxcache_frame1.ComputeWorldBound(mesh.GetPrim())
+        bbox1 = bounds1.GetRange().GetMax() - bounds1.GetRange().GetMin()
+        self.assertEqual(mesh.GetPointsAttr().GetTimeSamples(), [])
+        self.assertEqual(mesh.GetExtentAttr().GetTimeSamples(), [])
+        self.assertTrue(bbox1[0] > 0.0)
+        self.assertTrue(bbox1[1] > 0.0)
+        self.assertAlmostEqual(bbox1[2], 0.0, 5)
+
+        # Dynamic, flat, text
+        mesh = UsdGeom.Mesh(stage.GetPrimAtPath("/root/dynamic/dynamic"))
+        bounds1 = bboxcache_frame1.ComputeWorldBound(mesh.GetPrim())
+        bounds5 = bboxcache_frame5.ComputeWorldBound(mesh.GetPrim())
+        bbox1 = bounds1.GetRange().GetMax() - bounds1.GetRange().GetMin()
+        bbox5 = bounds5.GetRange().GetMax() - bounds5.GetRange().GetMin()
+        self.assertEqual(mesh.GetPointsAttr().GetTimeSamples(), [1.0, 2.0, 3.0, 4.0, 5.0])
+        self.assertEqual(mesh.GetExtentAttr().GetTimeSamples(), [1.0, 2.0, 3.0, 4.0, 5.0])
+        self.assertEqual(bbox1[2], 0.0)
+        self.assertTrue(bbox1[0] < bbox5[0])    # Text grows on x-axis
+        self.assertAlmostEqual(bbox1[1], bbox5[1], 5)
+        self.assertAlmostEqual(bbox1[2], bbox5[2], 5)
+
+        # Static, extruded on Z, text
+        mesh = UsdGeom.Mesh(stage.GetPrimAtPath("/root/extruded/extruded"))
+        bounds1 = bboxcache_frame1.ComputeWorldBound(mesh.GetPrim())
+        bbox1 = bounds1.GetRange().GetMax() - bounds1.GetRange().GetMin()
+        self.assertEqual(mesh.GetPointsAttr().GetTimeSamples(), [])
+        self.assertEqual(mesh.GetExtentAttr().GetTimeSamples(), [])
+        self.assertTrue(bbox1[0] > 0.0)
+        self.assertTrue(bbox1[1] > 0.0)
+        self.assertAlmostEqual(bbox1[2], 0.1, 5)
+
+        # Static, uses depth, text
+        mesh = UsdGeom.Mesh(stage.GetPrimAtPath("/root/has_depth/has_depth"))
+        bounds1 = bboxcache_frame1.ComputeWorldBound(mesh.GetPrim())
+        bbox1 = bounds1.GetRange().GetMax() - bounds1.GetRange().GetMin()
+        self.assertEqual(mesh.GetPointsAttr().GetTimeSamples(), [])
+        self.assertEqual(mesh.GetExtentAttr().GetTimeSamples(), [])
+        self.assertTrue(bbox1[0] > 0.0)
+        self.assertTrue(bbox1[1] > 0.0)
+        self.assertAlmostEqual(bbox1[2], 0.1, 5)
+
     def test_export_volumes(self):
         """Test various combinations of volume export including with all supported volume modifiers."""