Sam Haves
7d7648f7ed
This enables two workflows: 1) Users that parsed some other format into MjSpec, or built it programmatically can export animated USD easily with as minimal as possible interaction with USD. 2) Creating a spec from USD, then modifying the spec, should not cause a duplication of data when writing to USD. PiperOrigin-RevId: 827627520 Change-Id: I02c8c14a18569547710e54f3704d52ac0bf70ce6
80 lines
2.5 KiB
C++
80 lines
2.5 KiB
C++
// Copyright 2025 DeepMind Technologies Limited
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#include <mujoco/experimental/usd/writer.h>
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#include <utility>
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#include <vector>
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#include <mujoco/experimental/usd/utils.h>
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#include "experimental/usd/plugins/mjcf/mujoco_to_usd.h"
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#include <mujoco/mujoco.h>
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#include <pxr/usd/sdf/path.h>
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#include <pxr/usd/usd/common.h>
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#include <pxr/usd/usd/stage.h>
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namespace mujoco {
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namespace usd {
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// Writer is the main entry point for mj_usd. It is responsible
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// for converting the USD scene into a Mujoco model and exposing stepping
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// API.
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Writer::Writer(pxr::UsdStageRefPtr stage, mjSpec* spec, mjModel_* model)
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: stage_(stage), spec_(spec), model_(model) {
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WriteSpecsWithoutUSDOriginToLayer();
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BuildMjUsdMapping();
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}
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Writer::~Writer() = default;
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void Writer::WriteSpecsWithoutUSDOriginToLayer() {
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// The user may have constructed the spec from sources other than USD.
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// In this case, we will write write all those spec elements to a new layer in
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// the stage. This allows us to keep the same writing API for a simulation regardless
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// of how a spec was produced.
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mujoco::usd::WriteSpecToData(spec_, stage_->GetEditTarget().GetLayer(), true);
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}
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void Writer::BuildMjUsdMapping() {
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body_id_to_path_.assign(model_->nbody, pxr::SdfPath());
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// World body (ID 0) maps to an empty SdfPath.
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if (model_->nbody > 0) {
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body_id_to_path_[0] = pxr::SdfPath();
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}
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// Iterate over MuJoCo body IDs from the mjModel.
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for (int body_idx = 1; body_idx < model_->nbody; ++body_idx) {
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const char* body_name = mj_id2name(model_, mjOBJ_BODY, body_idx);
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if (body_name) {
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mjsBody* spec_body = mjs_findBody(spec_, body_name);
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body_id_to_path_[body_idx] =
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mujoco::usd::GetUsdPrimPathUserValue(spec_body->element);
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}
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}
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}
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void Writer::Update(const mjData* const data) {
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for (const auto& sink_fn : pose_sinks_) {
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sink_fn(data, body_id_to_path_);
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}
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}
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void Writer::AddSink(PoseSinkFn sink_fn) {
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pose_sinks_.push_back(std::move(sink_fn));
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}
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} // namespace usd
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} // namespace mujoco
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