MRMeshDecimateCallbacks.h

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#pragma once
 
#include "MRMesh.h"
#include "MRMeshAttributesToUpdate.h"
 
namespace MR
{
// callback that is called when before edge is collapsed 
// (i.e. in decimateMesh) and changes moved vertex attribute to correct value. 
// Useful to update vertices based attributes like uv coordinates or verts colormaps
template <typename T>
auto preCollapseVertAttribute( const Mesh& mesh, Vector<T, VertId>& data );
 
MRMESH_API PreCollapseCallback meshPreCollapseVertAttribute( const Mesh& mesh, const MeshAttributesToUpdate& params );
 
template <typename T>
auto preCollapseVertAttribute( const Mesh& mesh, Vector<T, VertId>& data )
{
    auto preCollapse = [&] ( EdgeId edgeToCollapse, const Vector3f& newEdgeOrgPos )
    {
        const auto org = mesh.topology.org( edgeToCollapse );
        const auto dest = mesh.topology.dest( edgeToCollapse );
        const auto orgPos = mesh.orgPnt( edgeToCollapse );
        const auto destPos = mesh.destPnt( edgeToCollapse );
 
        const auto ab = destPos - orgPos;
        const auto dt = dot( newEdgeOrgPos - orgPos, ab );
        const auto abLengthSq = ab.lengthSq();
        if ( dt <= 0 )
        {
            return true;
        }
 
        if ( dt >= abLengthSq )
        {
            data[org] = data[dest];
            return true;
        }
 
        const auto ratio = dt / abLengthSq;
        data[org] = ( 1 - ratio ) * data[org] + ratio * data[dest];
 
        return true;
    };
 
    return preCollapse;
}
 
}