smoothing.cpp | Explore in Territory

// Copyright 2021 The Manifold Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#include "./impl.h"
#include "./parallel.h"

namespace {
usingnamespacemanifold;

// Returns a normalized vector orthogonal to ref, in the plane of ref and in,
// unless in and ref are colinear, in which case it falls back to the plane of
// ref and altIn.
vec3 OrthogonalTo(vec3 in, vec3 altIn, vec3 ref) { … }

double Wrap(double radians) { … }

// Get the angle between two unit-vectors.
double AngleBetween(vec3 a, vec3 b) { … }

// Calculate a tangent vector in the form of a weighted cubic Bezier taking as
// input the desired tangent direction (length doesn't matter) and the edge
// vector to the neighboring vertex. In a symmetric situation where the tangents
// at each end are mirror images of each other, this will result in a circular
// arc.
vec4 CircularTangent(const vec3& tangent, const vec3& edgeVec) { … }

struct InterpTri { … };
}  // namespace

namespace manifold {

/**
 * Get the property normal associated with the startVert of this halfedge, where
 * normalIdx shows the beginning of where normals are stored in the properties.
 */
vec3 Manifold::Impl::GetNormal(int halfedge, int normalIdx) const { … }

/**
 * Returns a circular tangent for the requested halfedge, orthogonal to the
 * given normal vector, and avoiding folding.
 */
vec4 Manifold::Impl::TangentFromNormal(const vec3& normal, int halfedge) const { … }

/**
 * Returns true if this halfedge should be marked as the interior of a quad, as
 * defined by its two triangles referring to the same face, and those triangles
 * having no further face neighbors beyond.
 */
bool Manifold::Impl::IsInsideQuad(int halfedge) const { … }

/**
 * Returns true if this halfedge is an interior of a quad, as defined by its
 * halfedge tangent having negative weight.
 */
bool Manifold::Impl::IsMarkedInsideQuad(int halfedge) const { … }

// sharpenedEdges are referenced to the input Mesh, but the triangles have
// been sorted in creating the Manifold, so the indices are converted using
// meshRelation_.
std::vector<Smoothness> Manifold::Impl::UpdateSharpenedEdges(
    const std::vector<Smoothness>& sharpenedEdges) const { … }

// Find faces containing at least 3 triangles - these will not have
// interpolated normals - all their vert normals must match their face normal.
Vec<bool> Manifold::Impl::FlatFaces() const { … }

// Returns a vector of length numVert that has a tri that is part of a
// neighboring flat face if there is only one flat face. If there are none it
// gets -1, and if there are more than one it gets -2.
Vec<int> Manifold::Impl::VertFlatFace(const Vec<bool>& flatFaces) const { … }

Vec<int> Manifold::Impl::VertHalfedge() const { … }

std::vector<Smoothness> Manifold::Impl::SharpenEdges(
    double minSharpAngle, double minSmoothness) const { … }

/**
 * Sharpen tangents that intersect an edge to sharpen that edge. The weight is
 * unchanged, as this has a squared effect on radius of curvature, except
 * in the case of zero radius, which is marked with weight = 0.
 */
void Manifold::Impl::SharpenTangent(int halfedge, double smoothness) { … }

/**
 * Instead of calculating the internal shared normals like CalculateNormals
 * does, this method fills in vertex properties, unshared across edges that
 * are bent more than minSharpAngle.
 */
void Manifold::Impl::SetNormals(int normalIdx, double minSharpAngle) { … }

/**
 * Tangents get flattened to create sharp edges by setting their weight to zero.
 * This is the natural limit of reducing the weight to increase the sharpness
 * smoothly. This limit gives a decent shape, but it causes the parameterization
 * to be stretched and compresses it near the edges, which is good for resolving
 * tight curvature, but bad for property interpolation. This function fixes the
 * parameter stretch at the limit for sharp edges, since there is no curvature
 * to resolve. Note this also changes the overall shape - making it more evenly
 * curved.
 */
void Manifold::Impl::LinearizeFlatTangents() { … }

/**
 * Redistribute the tangents around each vertex so that the angles between them
 * have the same ratios as the angles of the triangles between the corresponding
 * edges. This avoids folding the output shape and gives smoother results. There
 * must be at least one fixed halfedge on a vertex for that vertex to be
 * operated on. If there is only one, then that halfedge is not treated as
 * fixed, but the whole circle is turned to an average orientation.
 */
void Manifold::Impl::DistributeTangents(const Vec<bool>& fixedHalfedges) { … }

/**
 * Calculates halfedgeTangent_, allowing the manifold to be refined and
 * smoothed. The tangents form weighted cubic Beziers along each edge. This
 * function creates circular arcs where possible (minimizing maximum curvature),
 * constrained to the indicated property normals. Across edges that form
 * discontinuities in the normals, the tangent vectors are zero-length, allowing
 * the shape to form a sharp corner with minimal oscillation.
 */
void Manifold::Impl::CreateTangents(int normalIdx) { … }

/**
 * Calculates halfedgeTangent_, allowing the manifold to be refined and
 * smoothed. The tangents form weighted cubic Beziers along each edge. This
 * function creates circular arcs where possible (minimizing maximum curvature),
 * constrained to the vertex normals. Where sharpenedEdges are specified, the
 * tangents are shortened that intersect the sharpened edge, concentrating the
 * curvature there, while the tangents of the sharp edges themselves are aligned
 * for continuity.
 */
void Manifold::Impl::CreateTangents(std::vector<Smoothness> sharpenedEdges) { … }

void Manifold::Impl::Refine(std::function<int(vec3, vec4, vec4)> edgeDivisions,
                            bool keepInterior) { … }

}  // namespace manifold
godot/thirdparty/manifold/src/smoothing.cpp
