First pass: primvar attribute writing works, but needs more varying types and more testing.

- Changed behavior as per Hans' suggestion-- now if UVs or Colors are chosen for import / export, Generic Attributes will follow.
- One more early out check.
- Added other TexCoord2x and TexCoord3x formats.

@@ -186,6 +181,55 @@ USDMeshReader::USDMeshReader(const pxr::UsdPrim &prim,
 {
 }
 
+static const int convert_usd_type_to_blender(const std::string usd_type)

@@ -188,1 +183,4 @@
 
+static const int convert_usd_type_to_blender(const std::string usd_type)
+{
+  static std::unordered_map<std::string, int> type_map{

@@ -189,0 +212,4 @@
+  return value->second;
+}
+
+static const int convert_usd_varying_to_blender(const std::string usd_domain)

@@ -189,0 +213,4 @@
+}
+
+static const int convert_usd_varying_to_blender(const std::string usd_domain)
+{

@@ -469,3 +344,2 @@
-
 void USDMeshReader::read_color_data_primvar(Mesh *mesh,
-                                            const pxr::UsdGeomPrimvar &color_primvar,
+                                            const pxr::UsdGeomPrimvar &primvar,

@@ -609,0 +486,4 @@
+  const StringRef primvar_name(primvar.StripPrimvarsName(primvar.GetName()).GetString());
+
+  pxr::VtArray<pxr::GfVec2d> usd_uvs;
+  if (!primvar.ComputeFlattened(&usd_uvs, motionSampleTime)) {

@@ -609,0 +495,4 @@
+
+  bke::MutableAttributeAccessor attributes = mesh->attributes_for_write();
+  bke::SpanAttributeWriter<float2> uv_data;
+  uv_data = attributes.lookup_or_add_for_write_only_span<float2>(primvar_name, ATTR_DOMAIN_CORNER);

@@ -609,0 +506,4 @@
+
+  for (int i = 0; i < usd_uvs.size(); i++) {
+    uv_data.span[i] = float2(usd_uvs[i][0], usd_uvs[i][1]);
+    ;

@@ -609,0 +525,4 @@
+
+template<typename T, typename U>
+void copy_prim_array_to_blender_buffer(const pxr::UsdGeomPrimvar &primvar,
+                                       bke::SpanAttributeWriter<U> &buffer,

@@ -609,0 +619,4 @@
+
+  switch (type) {
+    case CD_PROP_FLOAT: {
+      pxr::VtArray<float> primvar_array;

@@ -609,0 +625,4 @@
+      copy_prim_array_to_blender_buffer<float, float>(primvar, buffer, motionSampleTime);
+      break;
+    }
+    case CD_PROP_INT32: {

@@ -791,0 +867,4 @@
+    }
+
+    WM_reportf(RPT_WARNING,
+               "+++ Reading primvar %s, mesh %s (%s > %s)",

@@ -20,14 +18,10 @@
 #include "BKE_material.h"
 #include "BKE_mesh.hh"
 #include "BKE_mesh_wrapper.h"
-#include "BKE_modifier.h"

@@ -84,0 +88,4 @@
+          return true;
+        }
+
+        /* Splitting out the if clauses here so that we're only switching

@@ -95,0 +157,4 @@
+}
+
+template<typename T>
+const VArray<T> get_attribute_buffer(const Mesh *mesh,

@@ -95,0 +252,4 @@
+
+  if (prim_varying == empty_token || prim_attr_type == pxr::SdfValueTypeNames->Opaque) {
+    WM_reportf(RPT_WARNING,
+               "Mesh %s, Attribute %s cannot be converted to USD.",

@@ -95,0 +261,4 @@
+  pxr::UsdGeomPrimvar attribute_pv = pvApi.CreatePrimvar(
+      primvar_name, prim_attr_type, prim_varying);
+
+  switch (meta_data.data_type) {

@@ -95,0 +294,4 @@
+      break;
+    }
+    /*
+     * // This seems to be unsupported so far?

@@ -95,0 +314,4 @@
+                                         const bke::AttributeMetaData &meta_data,
+                                         const char *active_set_name)
+{
+  static blender::StringRef default_active_name = "st";

@@ -402,6 +410,7 @@ static int wm_usd_import_exec(bContext *C, wmOperator *op)
 
   const bool read_mesh_uvs = RNA_boolean_get(op->ptr, "read_mesh_uvs");
   const bool read_mesh_colors = RNA_boolean_get(op->ptr, "read_mesh_colors");
+  const bool read_mesh_attributes = RNA_boolean_get(op->ptr, "read_mesh_attributes");

@@ -0,0 +1,23 @@
+#ifndef BLENDER_USD_HASH_TYPES_H

@@ -0,0 +1,23 @@
+#ifndef BLENDER_USD_HASH_TYPES_H
+#define BLENDER_USD_HASH_TYPES_H

@@ -0,0 +3,4 @@
+
+#include <pxr/base/tf/token.h>
+#include <pxr/usd/sdf/valueTypeName.h>
+

@@ -90,0 +253,4 @@
+      meta_data.data_type);
+
+  if (!prim_varying.has_value() || !prim_attr_type.has_value()) {
+    WM_reportf(

@@ -312,0 +316,4 @@
+                  "export_mesh_colors",
+                  true,
+                  "Color Attributes",
+                  "Include Mesh Color Attributes in the export");

@@ -609,0 +514,4 @@
+  }
+
+  bke::MutableAttributeAccessor attributes = mesh->attributes_for_write();
+  bke::SpanAttributeWriter<float2> uv_data;

@@ -791,0 +925,4 @@
+                  pxr::UsdGeomTokens->faceVarying,
+                  pxr::UsdGeomTokens->varying) &&
+             ELEM(type,
+                  pxr::SdfValueTypeNames->TexCoord2dArray,

@@ -39,2 +34,4 @@
 namespace blender::io::usd {
 
+const pxr::TfToken empty_token;
+const pxr::UsdTimeCode defaultTime = pxr::UsdTimeCode::Default();

@@ -83,1 +87,4 @@
       [&](const bke::AttributeIDRef &attribute_id, const bke::AttributeMetaData &meta_data) {
+        /* Skipping "internal" Blender properties. Skipping
+         * material_index as it's dealt with elsewhere. Skipping
+         * edge sharp and crease because USD doesn't have a

@@ -84,0 +89,4 @@
+         * material_index as it's dealt with elsewhere. Skipping
+         * edge sharp and crease because USD doesn't have a
+         * conversion for them. */
+        if (attribute_id.name()[0] == '.' ||

@@ -95,0 +212,4 @@
+  usd_value_writer_.SetAttribute(prim_attr, pxr::VtValue(data), timecode);
+}
+
+#pragma optimize("", off)

@@ -95,0 +234,4 @@
+    return;
+  }
+
+  if (!prim_varying || !prim_varying.has_value() || !prim_attr_type || !prim_attr_type.has_value())

@@ -95,0 +247,4 @@
+      primvar_name, *prim_attr_type, *prim_varying);
+
+  switch (meta_data.data_type) {
+    case CD_PROP_FLOAT: {

@@ -95,0 +280,4 @@
+      break;
+    }
+    default:
+      BLI_assert_msg(0, "Unsupported domain for mesh data.");

@@ -95,0 +144,4 @@
+    case CD_PROP_QUATERNION:
+      return pxr::SdfValueTypeNames->QuatfArray;
+    default:
+      WM_reportf(RPT_WARNING, "Unsupported domain for mesh data.");

@@ -791,0 +906,4 @@
+
+    /* Read Color primvars. */
+    if (ELEM(type,
+             pxr::SdfValueTypeNames->Color3hArray,

@@ -791,0 +924,4 @@
+
+    /* Read UV primvars. */
+    else if (ELEM(varying_type,
+                  pxr::UsdGeomTokens->vertex,

@@ -95,0 +268,4 @@
+      copy_blender_buffer_to_prim<float2, pxr::GfVec2f>(
+          attribute.typed<float2>(), timecode, attribute_pv);
+      break;
+

@@ -609,0 +518,4 @@
+  }
+
+  bke::MutableAttributeAccessor attributes = mesh->attributes_for_write();
+  bke::SpanAttributeWriter<float2> uv_data = attributes.lookup_or_add_for_write_only_span<float2>(primvar_name, ATTR_DOMAIN_CORNER);

@@ -609,0 +535,4 @@
+      for (const int i : faces.index_range()) {
+        const IndexRange face = faces[i];
+        for (int j = 0; j < face.size(); j++) {
+          const int rev_index = face.start() + face.size() - 1 - j;

@@ -609,0 +550,4 @@
+    /* Handle vertex interpolation. */
+    const Span<int> corner_verts = mesh->corner_verts();
+    BLI_assert(mesh->totvert == usd_uvs.size());
+    for (int i = 0; i < uv_data.span.size(); ++i) {

@@ -609,0 +597,4 @@
+
+  if (ELEM(interp, pxr::UsdGeomTokens->constant, pxr::UsdGeomTokens->uniform)) {
+    /* For situations where there's only a single item, flood fill the object. */
+    attribute.fill(convert_value<USDT, BlenderT>(primvar_array[0]));

@@ -609,0 +607,4 @@
+      for (const int i : faces.index_range()) {
+        const IndexRange face = faces[i];
+        for (int j = 0; j < face.size(); j++) {
+          const int rev_index = face.start() + face.size() - 1 - j;

@@ -609,0 +663,4 @@
+      copy_prim_array_to_blender_attribute<int32_t>(
+          mesh, primvar, motionSampleTime, attribute.span.typed<int>());
+      break;
+

@@ -134,3 +344,2 @@
     default:
-      BLI_assert_msg(0, "Invalid domain for mesh color data.");
-      return;
+      BLI_assert_msg(0, "Invalid type for mesh color data.");

@@ -0,0 +1,26 @@
+/* SPDX-FileCopyrightText: 2023 Blender Foundation

@@ -188,0 +216,4 @@
+  const eAttrDomain *value = domain_map.lookup_ptr(usd_domain);
+
+  if (value == nullptr) {
+    WM_reportf(RPT_WARNING, "Unsupported domain for mesh data type %s.", usd_domain.GetText());

@@ -608,0 +511,4 @@
+      (varying_type == pxr::UsdGeomTokens->varying && usd_uvs.size() != mesh->totloop))
+  {
+    WM_reportf(RPT_WARNING,
+               "USD Import: uv attribute value '%s' count inconsistent with interpolation type",

@@ -188,0 +177,4 @@
+    map.add_new(pxr::SdfValueTypeNames->TexCoord3dArray, CD_PROP_FLOAT2);
+    map.add_new(pxr::SdfValueTypeNames->TexCoord3fArray, CD_PROP_FLOAT2);
+    map.add_new(pxr::SdfValueTypeNames->TexCoord3hArray, CD_PROP_FLOAT2);
+    map.add_new(pxr::SdfValueTypeNames->Float3Array, CD_PROP_FLOAT3);