SmoothedMeshGradientField.h

/*
 * Copyright 2026 Adobe. All rights reserved.
 * This file is licensed to you under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License. You may obtain a copy
 * of the License at http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software distributed under
 * the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR REPRESENTATIONS
 * OF ANY KIND, either express or implied. See the License for the specific language
 * governing permissions and limitations under the License.
 */
#pragma once
 
#include <lagrange/SurfaceMesh.h>
#include <lagrange/volume/api.h>
 
#include <Eigen/Core>
 
// clang-format off
#include <lagrange/utils/warnoff.h>
#include <openvdb/openvdb.h>
#include <openvdb/tools/Interpolation.h>
#include <lagrange/utils/warnon.h>
// clang-format on
 
namespace lagrange::volume {

class LA_VOLUME_API SmoothedMeshGradientField
{
public:
    using Grid = openvdb::Vec3SGrid;
    using Accessor = Grid::ConstAccessor;

    template <typename Scalar, typename Index>
    SmoothedMeshGradientField(
        const SurfaceMesh<Scalar, Index>& mesh,
        double voxel_size,
        double epsilon,
        double query_reach);

    Grid::ConstPtr grid() const { return m_grid; }

    Accessor accessor() const { return m_grid->getConstAccessor(); }

    bool sample_direction(
        const Eigen::Vector3d& position,
        Eigen::Vector3d& direction_out,
        Accessor* accessor = nullptr) const;
 
private:
    // The grid is never mutated after construction.
    Grid::Ptr m_grid;
};
 
} // namespace lagrange::volume