FaceNormalClustering.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "MathUtil.h"
 
namespace UE::Geometry
{
 
class FDynamicMesh3;
 
namespace FaceNormalClustering
{
    struct FClusterOptions
    {
        // If one minus the dot product of normals is greater than this value, they are similar enough to be joined together.
        double NormalOneMinusCosTolerance = .01;
        // The area threshold below which we ignore the computed triangle normal, and always merge to an adjacent group. Helps avoid tiny triangles failing to cluster due to unreliable normals.
        double SmallFaceAreaThreshold = FMathd::ZeroTolerance;
        // The minimum number of cluster groups below which to stop merging clusters
        int32 TargetMinGroups = 0;
        // Whether to consider the average normal of the whole cluster before merging. If false, will only consider the normals of the original triangles within a group.
        bool bApplyNormalToleranceToClusters = true;
 
        void SetNormalAngleToleranceInDegrees(double ToleranceInDegrees)
        {
            NormalOneMinusCosTolerance = 1 - FMathd::Cos(FMathd::DegToRad * ToleranceInDegrees);
        }
    };
 
    void GEOMETRYCORE_API ComputeMeshPolyGroupsFromClusters(FDynamicMesh3& Mesh, TArray<TArray<int32>>& OutPolyGroups, const FClusterOptions& Options, TSet<int32>* IgnoreEdges = nullptr);
 
     void GEOMETRYCORE_API ComputeClusterCornerVertices(FDynamicMesh3& Mesh, TArray<int32>& OutCornerVertices, const FClusterOptions& Options, TSet<int32>* IgnoreEdges = nullptr);
}
 
} // end namespace UE::Geometry