Merge remote-tracking branch 'origin/blender-v2.83-release'

source/blender/io/alembic/intern/abc_customdata.cc

@@ -144,7 +144,7 @@ const char *get_uv_sample(UVSample &sample, const CDStreamConfig &config, Custom
  * - (optional due to its behavior) tag as UV using Alembic::AbcGeom::SetIsUV
  */
 static void write_uv(const OCompoundProperty &prop,
-                     const CDStreamConfig &config,
+                     CDStreamConfig &config,
                      void *data,
                      const char *name)
 {
@@ -157,13 +157,18 @@ static void write_uv(const OCompoundProperty &prop,
     return;
   }
 
-  OV2fGeomParam param(prop, name, true, kFacevaryingScope, 1);
+  std::string uv_map_name(name);
+  OV2fGeomParam param = config.abc_uv_maps[uv_map_name];
 
+  if (!param.valid()) {
+    param = OV2fGeomParam(prop, name, true, kFacevaryingScope, 1);
+  }
   OV2fGeomParam::Sample sample(V2fArraySample(&uvs.front(), uvs.size()),
                                UInt32ArraySample(&indices.front(), indices.size()),
                                kFacevaryingScope);
-
   param.set(sample);
+
+  config.abc_uv_maps[uv_map_name] = param;
 }
 
 /* Convention to write Vertex Colors:
@@ -217,7 +222,7 @@ static void write_mcol(const OCompoundProperty &prop,
 }
 
 void write_custom_data(const OCompoundProperty &prop,
-                       const CDStreamConfig &config,
+                       CDStreamConfig &config,
                        CustomData *data,
                        int data_type)
 {

source/blender/io/alembic/intern/abc_customdata.h

@@ -27,6 +27,8 @@
 #include <Alembic/Abc/All.h>
 #include <Alembic/AbcGeom/All.h>
 
+#include <map>
+
 struct CustomData;
 struct MLoop;
 struct MLoopUV;
@@ -70,6 +72,12 @@ struct CDStreamConfig {
 
   const char **modifier_error_message;
 
+  /* Alembic needs Blender to keep references to C++ objects (the destructors
+   * finalise the writing to ABC). This map stores OV2fGeomParam objects for the
+   * 2nd and subsequent UV maps; the primary UV map is kept alive by the Alembic
+   * mesh sample itself. */
+  std::map<std::string, Alembic::AbcGeom::OV2fGeomParam> abc_uv_maps;
+
   CDStreamConfig()
       : mloop(NULL),
         totloop(0),
@@ -95,7 +103,7 @@ struct CDStreamConfig {
 const char *get_uv_sample(UVSample &sample, const CDStreamConfig &config, CustomData *data);
 
 void write_custom_data(const OCompoundProperty &prop,
-                       const CDStreamConfig &config,
+                       CDStreamConfig &config,
                        CustomData *data,
                        int data_type);
 

tests/python/alembic_tests.py

@@ -84,6 +84,7 @@ class AbstractAlembicTest(AbstractBlenderRunnerTest):
             'uint8_t': int,
             'int16_t': int,
             'int32_t': int,
+            'uint32_t': int,
             'uint64_t': int,
             'float64_t': float,
             'float32_t': float,
@@ -325,6 +326,60 @@ class HairParticlesExportTest(AbstractAlembicTest):
         self.assertIn('.faceIndices', abcprop)
 
 
+class UVMapExportTest(AbstractAlembicTest):
+    @with_tempdir
+    def test_uvmap_export(self, tempdir: pathlib.Path):
+        """Minimal test for exporting multiple UV maps on an animated mesh.
+
+        This covers the issue reported in T77021.
+        """
+        basename = 'T77021-multiple-uvmaps-animated-mesh'
+        abc = tempdir / f'{basename}.abc'
+        script = f"import bpy; bpy.ops.wm.alembic_export(filepath='{abc.as_posix()}', start=1, end=1, " \
+                 f"renderable_only=True, visible_objects_only=True, flatten=False)"
+        self.run_blender(f'{basename}.blend', script)
+
+        self.maxDiff = 1000
+
+        # The main UV map should be written to .geom
+        abcprop = self.abcprop(abc, '/Cube/CubeShape/.geom/uv')
+        self.assertEqual(abcprop['.vals'], [
+            [0.625, 0.75],
+            [0.875, 0.75],
+            [0.875, 0.5],
+            [0.625, 0.5],
+            [0.375, 1.0],
+            [0.625, 1.0],
+            [0.375, 0.75],
+            [0.375, 0.25],
+            [0.625, 0.25],
+            [0.625, 0.0],
+            [0.375, 0.0],
+            [0.125, 0.75],
+            [0.375, 0.5],
+            [0.125, 0.5],
+        ])
+
+        # The second UV map should be written to .arbGeomParams
+        abcprop = self.abcprop(abc, '/Cube/CubeShape/.geom/.arbGeomParams/Secondary')
+        self.assertEqual(abcprop['.vals'], [
+            [0.75, 0.375],
+            [0.75, 0.125],
+            [0.5, 0.125],
+            [0.5, 0.375],
+            [1.0, 0.625],
+            [1.0, 0.375],
+            [0.75, 0.625],
+            [0.25, 0.625],
+            [0.25, 0.375],
+            [0.0, 0.375],
+            [0.0, 0.625],
+            [0.75, 0.875],
+            [0.5, 0.625],
+            [0.5, 0.875],
+        ])
+
+
 class LongNamesExportTest(AbstractAlembicTest):
     @with_tempdir
     def test_export_long_names(self, tempdir: pathlib.Path):