39 lines
1.3 KiB
C++
39 lines
1.3 KiB
C++
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#pragma once
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#include "vde/core/point.h"
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#include <functional>
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#include <tuple>
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namespace vde::sdf {
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using core::Point3D;
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using core::Vector3D;
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/// Compute numerical gradient of a scalar field f at point p
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/// Uses central finite differences with step size h
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template <typename Fn>
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[[nodiscard]] Vector3D gradient(Fn&& f, const Point3D& p, double h = 1e-6) {
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double fx = f(p);
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const double eps_x = h * (1.0 + std::abs(p.x()));
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const double eps_y = h * (1.0 + std::abs(p.y()));
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const double eps_z = h * (1.0 + std::abs(p.z()));
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double dfdx = (f(Point3D(p.x() + eps_x, p.y(), p.z())) -
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f(Point3D(p.x() - eps_x, p.y(), p.z()))) / (2.0 * eps_x);
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double dfdy = (f(Point3D(p.x(), p.y() + eps_y, p.z())) -
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f(Point3D(p.x(), p.y() - eps_y, p.z()))) / (2.0 * eps_y);
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double dfdz = (f(Point3D(p.x(), p.y(), p.z() + eps_z)) -
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f(Point3D(p.x(), p.y(), p.z() - eps_z))) / (2.0 * eps_z);
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return Vector3D(dfdx, dfdy, dfdz);
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}
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/// Evaluate scalar field and its gradient at point p (joint pass)
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/// Returns (value, gradient)
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template <typename Fn>
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[[nodiscard]] std::tuple<double, Vector3D> evaluate_with_gradient(
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Fn&& f, const Point3D& p, double h = 1e-6) {
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return {f(p), gradient(std::forward<Fn>(f), p, h)};
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}
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} // namespace vde::sdf
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