isotropic_remeshing.cpp

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#include "isotropic_remeshing.hpp"
 
#include <wmtk/EdgeMesh.hpp>
#include <wmtk/Scheduler.hpp>
#include <wmtk/TriMesh.hpp>
#include <wmtk/invariants/FusionEdgeInvariant.hpp>
#include <wmtk/invariants/InteriorSimplexInvariant.hpp>
#include <wmtk/invariants/InvariantCollection.hpp>
#include <wmtk/invariants/MaxEdgeLengthInvariant.hpp>
#include <wmtk/invariants/MinEdgeLengthInvariant.hpp>
#include <wmtk/invariants/MultiMeshLinkConditionInvariant.hpp>
#include <wmtk/invariants/MultiMeshMapValidInvariant.hpp>
#include <wmtk/invariants/SimplexInversionInvariant.hpp>
#include <wmtk/invariants/ValenceImprovementInvariant.hpp>
#include <wmtk/invariants/uvEdgeInvariant.hpp>
#include <wmtk/io/ParaviewWriter.hpp>
#include <wmtk/multimesh/MultiMeshVisitor.hpp>
#include <wmtk/multimesh/consolidate.hpp>
#include <wmtk/operations/AttributesUpdate.hpp>
#include <wmtk/operations/EdgeCollapse.hpp>
#include <wmtk/operations/EdgeSplit.hpp>
#include <wmtk/operations/attribute_new/CollapseNewAttributeStrategy.hpp>
#include <wmtk/operations/attribute_new/SplitNewAttributeStrategy.hpp>
#include <wmtk/operations/attribute_update/AttributeTransferStrategy.hpp>
#include <wmtk/operations/composite/TriEdgeSwap.hpp>
#include <wmtk/operations/utils/VertexLaplacianSmooth.hpp>
#include <wmtk/operations/utils/VertexTangentialLaplacianSmooth.hpp>
#include <wmtk/utils/Logger.hpp>
 
 
#include <Eigen/Geometry>
#include <wmtk/invariants/InvariantCollection.hpp>
#include "IsotropicRemeshingOptions.hpp"
 
namespace wmtk::components::isotropic_remeshing {
// compute the length relative to the bounding box diagonal
double relative_to_absolute_length(
    const attribute::MeshAttributeHandle& position,
    const double length_rel)
{
    auto pos = position.mesh().create_const_accessor<double>(position);
    const auto vertices = position.mesh().get_all(PrimitiveType::Vertex);
    Eigen::AlignedBox<double, Eigen::Dynamic> bbox(pos.dimension());
 
 
    for (const auto& v : vertices) {
        bbox.extend(pos.const_vector_attribute(v));
    }
 
    const double diag_length = bbox.sizes().norm();
 
    return length_rel * diag_length;
}
 
 
void isotropic_remeshing(const IsotropicRemeshingOptions& options)
{
    auto position = options.position_attribute;
 
    if (position.mesh().top_simplex_type() != PrimitiveType::Triangle) {
        log_and_throw_error(
            "isotropic remeshing works only for triangle meshes: {}",
            primitive_type_name(position.mesh().top_simplex_type()));
    }
 
    auto pass_through_attributes = options.pass_through_attributes;
    auto other_positions = options.other_position_attributes;
 
    double length = options.length_abs;
    if (options.length_abs < 0) {
        if (options.length_rel < 0) {
            throw std::runtime_error("Either absolute or relative length must be set!");
        }
        length = relative_to_absolute_length(position, options.length_rel);
    }
 
    // clear attributes
    std::vector<attribute::MeshAttributeHandle> keeps = pass_through_attributes;
    keeps.emplace_back(position);
    keeps.insert(keeps.end(), other_positions.begin(), other_positions.end());
 
    // TODO: brig me back!
    // mesh_in->clear_attributes(keeps);
 
    // gather handles again as they were invalidated by clear_attributes
    // positions = utils::get_attributes(cache, *mesh_in,
    // options.position_attribute); assert(positions.size() == 1); position =
    // positions.front(); pass_through_attributes = utils::get_attributes(cache,
    // *mesh_in, options.pass_through_attributes);
 
    std::optional<attribute::MeshAttributeHandle> position_for_inversion =
        options.inversion_position_attribute;
 
 
    assert(dynamic_cast<TriMesh*>(&position.mesh()) != nullptr);
 
    TriMesh& mesh = static_cast<TriMesh&>(position.mesh());
 
    const double length_min = (4. / 5.) * length;
    const double length_max = (4. / 3.) * length;
 
    std::vector<attribute::MeshAttributeHandle> positions = other_positions;
    positions.push_back(position);
 
    auto invariant_link_condition =
        std::make_shared<wmtk::invariants::MultiMeshLinkConditionInvariant>(mesh);
 
    auto invariant_min_edge_length = std::make_shared<MinEdgeLengthInvariant>(
        mesh,
        position.as<double>(),
        length_max * length_max);
 
    auto invariant_max_edge_length = std::make_shared<MaxEdgeLengthInvariant>(
        mesh,
        position.as<double>(),
        length_min * length_min);
 
    auto invariant_interior_edge = std::make_shared<invariants::InvariantCollection>(mesh);
    auto invariant_interior_vertex = std::make_shared<invariants::InvariantCollection>(mesh);
 
    auto set_all_invariants = [&](auto&& m) {
        invariant_interior_edge->add(
            std::make_shared<invariants::InteriorSimplexInvariant>(m, PrimitiveType::Edge));
        invariant_interior_vertex->add(
            std::make_shared<invariants::InteriorSimplexInvariant>(m, PrimitiveType::Vertex));
    };
    multimesh::MultiMeshVisitor visitor(set_all_invariants);
    visitor.execute_from_root(mesh);
 
    auto invariant_valence_improve =
        std::make_shared<invariants::ValenceImprovementInvariant>(mesh);
 
    auto invariant_mm_map = std::make_shared<MultiMeshMapValidInvariant>(mesh);
 
    auto update_position_func = [](const Eigen::MatrixXd& P) -> Eigen::VectorXd {
        return P.col(0);
    };
    std::shared_ptr<wmtk::operations::SingleAttributeTransferStrategy<double, double>>
        update_position;
 
    if (!options.other_position_attributes.empty()) {
        update_position =
            std::make_shared<wmtk::operations::SingleAttributeTransferStrategy<double, double>>(
                other_positions.front(),
                position,
                update_position_func);
    }
 
    using namespace operations;
 
    assert(mesh.is_connectivity_valid());
 
    std::vector<std::shared_ptr<Operation>> ops;
 
    // split
    wmtk::logger().debug("Configure isotropic remeshing split");
    auto op_split = std::make_shared<EdgeSplit>(mesh);
    op_split->add_invariant(invariant_min_edge_length);
    if (options.lock_boundary && !options.use_for_periodic && !options.dont_disable_split) {
        op_split->add_invariant(invariant_interior_edge);
    }
    for (auto& p : positions) {
        op_split->set_new_attribute_strategy(
            p,
            SplitBasicStrategy::None,
            SplitRibBasicStrategy::Mean);
    }
    for (const auto& attr : pass_through_attributes) {
        op_split->set_new_attribute_strategy(attr);
    }
    assert(op_split->attribute_new_all_configured());
    ops.push_back(op_split);
 
 
    // collapse
    wmtk::logger().debug("Configure isotropic remeshing collapse");
    auto op_collapse = std::make_shared<EdgeCollapse>(mesh);
    op_collapse->add_invariant(invariant_link_condition);
    if (position_for_inversion) {
        op_collapse->add_invariant(std::make_shared<SimplexInversionInvariant<double>>(
            position_for_inversion.value().mesh(),
            position_for_inversion.value().as<double>()));
    }
 
    op_collapse->add_invariant(invariant_max_edge_length);
    op_collapse->add_invariant(invariant_mm_map);
 
    // hack for uv
    if (options.fix_uv_seam) {
        op_collapse->add_invariant(
            std::make_shared<invariants::uvEdgeInvariant>(mesh, other_positions.front().mesh()));
    }
 
    if (options.lock_boundary && !options.use_for_periodic) {
        op_collapse->add_invariant(invariant_interior_edge);
        // set collapse towards boundary
        for (auto& p : positions) {
            auto tmp = std::make_shared<CollapseNewAttributeStrategy<double>>(p);
            tmp->set_strategy(CollapseBasicStrategy::Mean);
            tmp->set_simplex_predicate(BasicSimplexPredicate::IsInterior);
            op_collapse->set_new_attribute_strategy(p, tmp);
        }
    } else if (options.use_for_periodic) {
        op_collapse->add_invariant(
            std::make_shared<invariants::FusionEdgeInvariant>(mesh, mesh.get_multi_mesh_root()));
        for (auto& p : positions) {
            op_collapse->set_new_attribute_strategy(p, CollapseBasicStrategy::Mean);
        }
    } else {
        for (auto& p : positions) {
            op_collapse->set_new_attribute_strategy(p, CollapseBasicStrategy::Mean);
        }
    }
 
 
    for (const auto& attr : pass_through_attributes) {
        op_collapse->set_new_attribute_strategy(attr);
    }
    assert(op_collapse->attribute_new_all_configured());
    ops.push_back(op_collapse);
 
 
    // swap
    wmtk::logger().debug("Configure isotropic remeshing swap");
    auto op_swap = std::make_shared<composite::TriEdgeSwap>(mesh);
    op_swap->add_invariant(invariant_interior_edge);
 
    // hack for uv
    if (options.fix_uv_seam) {
        op_swap->add_invariant(
            std::make_shared<invariants::uvEdgeInvariant>(mesh, other_positions.front().mesh()));
    }
 
    op_swap->add_invariant(invariant_valence_improve);
    op_swap->collapse().add_invariant(invariant_link_condition);
    op_swap->collapse().add_invariant(invariant_mm_map);
    for (auto& p : positions) {
        op_swap->split().set_new_attribute_strategy(
            p,
            SplitBasicStrategy::None,
            SplitRibBasicStrategy::Mean);
    }
    if (position_for_inversion) {
        op_swap->collapse().add_invariant(std::make_shared<SimplexInversionInvariant<double>>(
            position_for_inversion.value().mesh(),
            position_for_inversion.value().as<double>()));
    }
 
    for (auto& p : positions)
        op_swap->collapse().set_new_attribute_strategy(p, CollapseBasicStrategy::CopyOther);
    for (const auto& attr : pass_through_attributes) {
        op_swap->split().set_new_attribute_strategy(attr);
        op_swap->collapse().set_new_attribute_strategy(attr);
    }
    assert(op_swap->split().attribute_new_all_configured());
    assert(op_swap->collapse().attribute_new_all_configured());
    ops.push_back(op_swap);
 
 
    // smooth
    auto op_smooth = std::make_shared<AttributesUpdateWithFunction>(mesh);
    if (position.dimension() == 3) {
        op_smooth->set_function(VertexTangentialLaplacianSmooth(position));
    } else {
        op_smooth->set_function(VertexLaplacianSmooth(position));
    }
 
    if (options.lock_boundary) {
        op_smooth->add_invariant(invariant_interior_vertex);
    }
 
    // hack for uv
    if (options.fix_uv_seam) {
        op_smooth->add_invariant(
            std::make_shared<invariants::uvEdgeInvariant>(mesh, other_positions.front().mesh()));
    }
 
    if (position_for_inversion) {
        op_smooth->add_invariant(std::make_shared<SimplexInversionInvariant<double>>(
            position_for_inversion.value().mesh(),
            position_for_inversion.value().as<double>()));
    }
 
    if (update_position) op_smooth->add_transfer_strategy(update_position);
    ops.push_back(op_smooth);
 
 
    Scheduler scheduler;
    for (long i = 0; i < options.iterations; ++i) {
        wmtk::logger().info("Iteration {}", i);
 
        SchedulerStats pass_stats;
        for (size_t j = 0; j < ops.size(); ++j) {
            const auto& op = ops[j];
            pass_stats += scheduler.run_operation_on_all(*op);
        }
 
        multimesh::consolidate(mesh);
 
        logger().info(
            "Executed {} ops (S/F) {}/{}. Time: collecting: {}, sorting: {}, executing: {}",
            pass_stats.number_of_performed_operations(),
            pass_stats.number_of_successful_operations(),
            pass_stats.number_of_failed_operations(),
            pass_stats.collecting_time,
            pass_stats.sorting_time,
            pass_stats.executing_time);
 
        multimesh::consolidate(mesh);
    }
}
} // namespace wmtk::components::isotropic_remeshing