feat(v3.6): TrimmedSurface — B-Rep fundamental primitive

include/vde/brep/trimmed_surface.h

@@ -0,0 +1,54 @@
+#pragma once
+#include "vde/curves/nurbs_surface.h"
+#include "vde/curves/nurbs_curve.h"
+#include "vde/core/point.h"
+#include "vde/core/aabb.h"
+#include <optional>
+#include <vector>
+
+namespace vde::brep {
+
+/// A p-curve: 2D curve in the parameter space of a surface
+/// We reuse NurbsCurve with Z=0 — only X (u) and Y (v) are meaningful.
+using PCurve = curves::NurbsCurve;
+
+/// Trimming loop: closed contour in parameter space (u, v)
+/// An outer loop defines the boundary; inner loops define holes.
+struct TrimLoop {
+    std::vector<PCurve> p_curves;  ///< parameter-space curves forming the loop
+    bool is_outer = true;          ///< true = outer boundary, false = hole
+};
+
+/// A trimmed surface: base NURBS surface + trimming loops in parameter space
+///
+/// Point classification: a parameter (u, v) is INSIDE if it lies within
+/// the outer loop AND outside all inner loops.
+///
+/// This is the fundamental B-Rep primitive used by all industrial CAD kernels
+/// (Parasolid, ACIS, CGM).
+///
+/// @ingroup brep
+struct TrimmedSurface {
+    curves::NurbsSurface base_surface;  ///< Underlying geometry
+    std::vector<TrimLoop> loops;        ///< Trimming loops (first = outer boundary if marked)
+
+    /// Evaluate the surface at (u, v).
+    /// Returns the 3D point only if (u, v) is inside the trimmed region.
+    /// @return Point3D if inside, std::nullopt if outside
+    [[nodiscard]] std::optional<core::Point3D> evaluate(double u, double v) const;
+
+    /// Check if a parameter point is inside the trimmed region
+    [[nodiscard]] bool is_inside(double u, double v) const;
+
+    /// Get the axis-aligned bounding box of the trimmed surface
+    [[nodiscard]] core::AABB3D bounds() const;
+
+    /// Create an untrimmed surface (full parameter domain)
+    static TrimmedSurface from_surface(const curves::NurbsSurface& surf);
+
+    /// Create a rectangular trimmed surface
+    static TrimmedSurface from_rect(const curves::NurbsSurface& surf,
+                                    double u0, double u1, double v0, double v1);
+};
+
+} // namespace vde::brep