thin_plate_spline_body_center_of_mass_scaling_step.h

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#pragma once
 
#include <libopynsim/solvers/model_warper/toggleable_thin_plate_spline_scaling_step.h>
#include <libopynsim/solvers/model_warper/scaling_cache.h>
#include <libopynsim/solvers/model_warper/scaling_parameters.h>
#include <libopynsim/solvers/model_warper/scaling_step_validation_message.h>
#include <libopynsim/solvers/model_warper/scaling_step_validation_state.h>
#include <libopynsim/utilities/open_sim_helpers.h>
 
#include <liboscar/utilities/assertions.h>
#include <OpenSim/Simulation/SimbodyEngine/Body.h>
#include <SimTKcommon/SmallMatrix.h>
 
#include <format>
#include <string>
#include <vector>
 
namespace OpenSim { class Model; }
 
namespace opyn
{
    // A `ScalingStep` that applies the Thin-Plate Spline (TPS) warp the centers
    // of mass of the given bodies (opensim-creator#1147).
    class ThinPlateSplineBodyCenterOfMassScalingStep final : public ToggleableThinPlateSplineScalingStep {
        OpenSim_DECLARE_CONCRETE_OBJECT(ThinPlateSplineBodyCenterOfMassScalingStep, ToggleableThinPlateSplineScalingStep)
 
        OpenSim_DECLARE_LIST_PROPERTY(bodies, std::string, "Query paths (e.g. `/bodyset/*`) that the engine should use to find bodies in the source model that should be warped by this scaling step.");
 
    public:
        explicit ThinPlateSplineBodyCenterOfMassScalingStep() :
            ToggleableThinPlateSplineScalingStep{"Apply Thin-Plate Spline (TPS) to Body Centers of Mass"}
        {
            setDescription("Warps the locations of body centers of mass in the model using the Thin-Plate Spline (TPS) warping algorithm.");
            constructProperty_bodies();
        }
    private:
        std::vector<ScalingStepValidationMessage> implValidate(
            ScalingCache& cache,
            const ScalingParameters& params,
            const OpenSim::Model& sourceModel) const final
        {
            // Get base class validation messages.
            auto messages = ToggleableThinPlateSplineScalingStep::implValidate(cache, params, sourceModel);
 
            // Ensure every entry in `bodies` can be found in the source model.
            for (int i = 0; i < getProperty_bodies().size(); ++i) {
                if (not FindComponent<OpenSim::Body>(sourceModel, get_bodies(i))) {
                    messages.emplace_back(
                        ScalingStepValidationState::Error,
                        std::format("{}: Cannot find a Body in 'bodies' in the source model (or it isn't a Body)", get_bodies(i))
                    );
                }
            }
 
            return messages;
        }
 
        void implApplyScalingStep(
            ScalingCache& scalingCache,
            const ScalingParameters& parameters,
            const OpenSim::Model& sourceModel,
            OpenSim::Model& resultModel) const final
        {
            const auto commonParams = calcTPSScalingStepCommonParams(parameters, sourceModel, resultModel);
 
            // Warp each specified center of mass, ensuring that the CoM is correctly
            // transformed into the TPS warp's coordinate system.
            for (int i = 0; i < getProperty_bodies().size(); ++i) {
 
                // Find the CoM in the source model.
                const auto* sourceBody = FindComponent<OpenSim::Body>(sourceModel, get_bodies(i));
                OSC_ASSERT_ALWAYS(sourceBody && "could not find a body in the source model");
 
                // Find the CoM in the result model (i.e. the one that's midway through warping).
                const auto* resultBody = FindComponent<OpenSim::Body>(resultModel, get_bodies(i));
                OSC_ASSERT_ALWAYS(resultBody && "could not find a body in the result model");
 
                // Warp the CoM, while accounting for different frames etc. between the TPS
                // landmarks and the CoM.
                const SimTK::Vec3 warpedLocation = scalingCache.lookupTPSWarpedRigidPoint(
                    sourceModel,
                    resultModel,
                    sourceBody->get_mass_center(),
                    resultBody->get_mass_center(),
                    *sourceBody,
                    *resultBody,
                    *commonParams.sourceLandmarksFrame,
                    *commonParams.resultLandmarksFrame,
                    commonParams.tpsInputs,
                    commonParams.compensateForFrameChanges
                );
 
                // Update the body with the new CoM
                auto* resultBodyMut = FindComponentMut<OpenSim::Body>(resultModel, get_bodies(i));
                OSC_ASSERT_ALWAYS(resultBodyMut  && "could not find a corresponding body in the result model");
                resultBodyMut->set_mass_center(warpedLocation);
            }
            InitializeModel(resultModel);
            InitializeState(resultModel);
        }
    };
}