usd_writer_abstract.cc

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/*
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 * The Original Code is Copyright (C) 2019 Blender Foundation.
 * All rights reserved.
 */
#include "usd_writer_abstract.h"
#include "usd_hierarchy_iterator.h"
 
#include <pxr/base/tf/stringUtils.h>
 
#include "BLI_assert.h"
 
/* TfToken objects are not cheap to construct, so we do it once. */
namespace usdtokens {
/* Materials */
static const pxr::TfToken diffuse_color("diffuseColor", pxr::TfToken::Immortal);
static const pxr::TfToken metallic("metallic", pxr::TfToken::Immortal);
static const pxr::TfToken preview_shader("previewShader", pxr::TfToken::Immortal);
static const pxr::TfToken preview_surface("UsdPreviewSurface", pxr::TfToken::Immortal);
static const pxr::TfToken roughness("roughness", pxr::TfToken::Immortal);
static const pxr::TfToken surface("surface", pxr::TfToken::Immortal);
}  // namespace usdtokens
 
namespace blender::io::usd {
 
USDAbstractWriter::USDAbstractWriter(const USDExporterContext &usd_export_context)
    : usd_export_context_(usd_export_context), frame_has_been_written_(false), is_animated_(false)
{
}
 
bool USDAbstractWriter::is_supported(const HierarchyContext * /*context*/) const
{
  return true;
}
 
pxr::UsdTimeCode USDAbstractWriter::get_export_time_code() const
{
  if (is_animated_) {
    return usd_export_context_.hierarchy_iterator->get_export_time_code();
  }
  /* By using the default timecode USD won't even write a single `timeSample` for non-animated
   * data. Instead, it writes it as non-timesampled. */
  static pxr::UsdTimeCode default_timecode = pxr::UsdTimeCode::Default();
  return default_timecode;
}
 
void USDAbstractWriter::write(HierarchyContext &context)
{
  if (!frame_has_been_written_) {
    is_animated_ = usd_export_context_.export_params.export_animation &&
                   check_is_animated(context);
  }
  else if (!is_animated_) {
    /* A frame has already been written, and without animation one frame is enough. */
    return;
  }
 
  do_write(context);
 
  frame_has_been_written_ = true;
}
 
const pxr::SdfPath &USDAbstractWriter::usd_path() const
{
  return usd_export_context_.usd_path;
}
 
pxr::UsdShadeMaterial USDAbstractWriter::ensure_usd_material(Material *material)
{
  static pxr::SdfPath material_library_path("/_materials");
  pxr::UsdStageRefPtr stage = usd_export_context_.stage;
 
  /* Construct the material. */
  pxr::TfToken material_name(usd_export_context_.hierarchy_iterator->get_id_name(&material->id));
  pxr::SdfPath usd_path = material_library_path.AppendChild(material_name);
  pxr::UsdShadeMaterial usd_material = pxr::UsdShadeMaterial::Get(stage, usd_path);
  if (usd_material) {
    return usd_material;
  }
  usd_material = pxr::UsdShadeMaterial::Define(stage, usd_path);
 
  /* Construct the shader. */
  pxr::SdfPath shader_path = usd_path.AppendChild(usdtokens::preview_shader);
  pxr::UsdShadeShader shader = pxr::UsdShadeShader::Define(stage, shader_path);
  shader.CreateIdAttr(pxr::VtValue(usdtokens::preview_surface));
  shader.CreateInput(usdtokens::diffuse_color, pxr::SdfValueTypeNames->Color3f)
      .Set(pxr::GfVec3f(material->r, material->g, material->b));
  shader.CreateInput(usdtokens::roughness, pxr::SdfValueTypeNames->Float).Set(material->roughness);
  shader.CreateInput(usdtokens::metallic, pxr::SdfValueTypeNames->Float).Set(material->metallic);
 
  /* Connect the shader and the material together. */
  usd_material.CreateSurfaceOutput().ConnectToSource(shader, usdtokens::surface);
 
  return usd_material;
}
 
void USDAbstractWriter::write_visibility(const HierarchyContext &context,
                                         const pxr::UsdTimeCode timecode,
                                         pxr::UsdGeomImageable &usd_geometry)
{
  pxr::UsdAttribute attr_visibility = usd_geometry.CreateVisibilityAttr(pxr::VtValue(), true);
 
  const bool is_visible = context.is_object_visible(
      usd_export_context_.export_params.evaluation_mode);
  const pxr::TfToken visibility = is_visible ? pxr::UsdGeomTokens->inherited :
                                               pxr::UsdGeomTokens->invisible;
 
  usd_value_writer_.SetAttribute(attr_visibility, pxr::VtValue(visibility), timecode);
}
 
/* Reference the original data instead of writing a copy. */
bool USDAbstractWriter::mark_as_instance(const HierarchyContext &context, const pxr::UsdPrim &prim)
{
  BLI_assert(context.is_instance());
 
  if (context.export_path == context.original_export_path) {
    printf("USD ref error: export path is reference path: %s\n", context.export_path.c_str());
    BLI_assert(!"USD reference error");
    return false;
  }
 
  pxr::SdfPath ref_path(context.original_export_path);
  if (!prim.GetReferences().AddInternalReference(ref_path)) {
    /* See this URL for a description fo why referencing may fail"
     * https://graphics.pixar.com/usd/docs/api/class_usd_references.html#Usd_Failing_References
     */
    printf("USD Export warning: unable to add reference from %s to %s, not instancing object\n",
           context.export_path.c_str(),
           context.original_export_path.c_str());
    return false;
  }
 
  return true;
}
 
}  // namespace blender::io::usd