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cspace_separating_plane.cc
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cspace_separating_plane.cc
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#include "drake/geometry/optimization/cspace_separating_plane.h"
#include <utility>
#include "drake/common/symbolic/monomial_util.h"
namespace drake {
namespace geometry {
namespace optimization {
namespace {
template <typename T>
void InitializeCoeffVects(const VectorX<T>& decision_variables,
Eigen::Matrix<T, 3, Eigen::Dynamic>* a_coeff,
VectorX<T>* b_coeff) {
static_assert(std::is_same_v<T, symbolic::Variable> ||
std::is_same_v<T, double>);
const int num_coeffs_per_poly = decision_variables.size() / 4;
int var_count = 0;
for (int i = 0; i < 3; ++i) {
a_coeff->row(i) =
decision_variables.segment(var_count, num_coeffs_per_poly);
var_count += num_coeffs_per_poly;
}
*b_coeff = decision_variables.segment(var_count, num_coeffs_per_poly);
var_count += num_coeffs_per_poly;
DRAKE_DEMAND(var_count == decision_variables.size());
}
template <typename T>
void MakeCalcPlanePolynomial(const VectorX<symbolic::Variable>& vars_for_plane,
const int plane_degree,
const Eigen::Matrix<T, 3, Eigen::Dynamic>& a_coeff,
const VectorX<T>& b_coeff,
Vector3<symbolic::Polynomial>* a_val,
symbolic::Polynomial* b_val) {
static_assert(std::is_same_v<T, symbolic::Variable> ||
std::is_same_v<T, double>);
const Eigen::Matrix<symbolic::Monomial, Eigen::Dynamic, 1> basis =
symbolic::MonomialBasis(symbolic::Variables{vars_for_plane},
plane_degree);
for (int i = 0; i < 3; ++i) {
symbolic::Polynomial::MapType monomial_to_coeff_map;
for (int j = 0; j < basis.size(); ++j) {
monomial_to_coeff_map.emplace(basis(j), a_coeff(i, j));
}
(*a_val)(i) = symbolic::Polynomial(monomial_to_coeff_map);
}
symbolic::Polynomial::MapType monomial_to_coeff_map;
for (int j = 0; j < basis.size(); ++j) {
monomial_to_coeff_map.emplace(basis(j), b_coeff(j));
}
*b_val = symbolic::Polynomial(monomial_to_coeff_map);
}
Eigen::VectorXd ComputeGradedRevLexEvaluatedPowers(
const VectorX<double>& values, const int degree) {
const int num_vars = values.size();
symbolic::Variables vars;
symbolic::Environment evals;
for (int i = 0; i < num_vars; ++i) {
const symbolic::Variable cur_var{fmt::format("x{}", i)};
vars.insert(cur_var);
evals.insert(cur_var, values(i));
}
// Make a grevlex basis that we can now evaluate with the desired
// values.
VectorX<symbolic::Monomial> basis = symbolic::MonomialBasis(vars, degree);
Eigen::VectorXd ret{basis.size()};
for (int i = 0; i < basis.size(); ++i) {
ret(i) = basis(i).Evaluate(evals);
}
return ret;
}
template <typename T1, typename T2, typename T3>
void CalcPlaneImpl(const VectorX<T1>& decision_variables,
const VectorX<T2>& vars_for_plane, int plane_degree,
Vector3<T3>* a_val, T3* b_val) {
const int num_vars = vars_for_plane.size();
const int num_coeffs_per_poly =
symbolic::NChooseK(num_vars + plane_degree, plane_degree);
DRAKE_DEMAND(decision_variables.size() == 4 * num_coeffs_per_poly);
Eigen::Matrix<T1, 3, Eigen::Dynamic> a_coeff(3, num_coeffs_per_poly);
VectorX<T1> b_coeff(num_coeffs_per_poly);
InitializeCoeffVects(decision_variables, &a_coeff, &b_coeff);
if constexpr (std::is_same_v<T3, symbolic::Polynomial>) {
MakeCalcPlanePolynomial(vars_for_plane, plane_degree, a_coeff, b_coeff,
a_val, b_val);
} else {
const Eigen::VectorXd evaluated_powers =
ComputeGradedRevLexEvaluatedPowers(vars_for_plane, plane_degree);
(*a_val) = a_coeff * evaluated_powers;
(*b_val) = b_coeff.transpose() * evaluated_powers;
}
}
} // namespace
SeparatingPlaneOrder ToPlaneOrder(int plane_degree) {
if (plane_degree == 1) {
return SeparatingPlaneOrder::kAffine;
} else {
throw std::runtime_error(fmt::format(
"ToPlaneOrder: plane_degree={}, only supports plane_degree = 1.",
plane_degree));
}
}
int ToPlaneDegree(SeparatingPlaneOrder plane_order) {
switch (plane_order) {
case SeparatingPlaneOrder::kAffine: {
return 1;
}
}
DRAKE_UNREACHABLE();
}
namespace internal {
void CalcPlane(const VectorX<symbolic::Variable>& decision_variables,
const VectorX<symbolic::Variable>& vars_for_plane,
int plane_degree, Vector3<symbolic::Polynomial>* a_val,
symbolic::Polynomial* b_val) {
CalcPlaneImpl(decision_variables, vars_for_plane, plane_degree, a_val, b_val);
}
void CalcPlane(const VectorX<double>& decision_variables,
const VectorX<symbolic::Variable>& vars_for_plane,
int plane_degree, Vector3<symbolic::Polynomial>* a_val,
symbolic::Polynomial* b_val) {
CalcPlaneImpl(decision_variables, vars_for_plane, plane_degree, a_val, b_val);
}
void CalcPlane(const VectorX<double>& decision_variables,
const VectorX<double>& vars_for_plane, int plane_degree,
Vector3<double>* a_val, double* b_val) {
CalcPlaneImpl(decision_variables, vars_for_plane, plane_degree, a_val, b_val);
}
} // namespace internal
} // namespace optimization
} // namespace geometry
} // namespace drake