GEO_SplitPoints.C

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/*
 * Copyright (c) 2025
 *      Side Effects Software Inc.  All rights reserved.
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 *----------------------------------------------------------------------------
 * Definitions of functions for splitting points based on vertices or primitives
 */

#include "GEO_SplitPoints.h"

#include <GEO/GEO_Detail.h>
#include <GA/GA_ATINumeric.h>
#include <GA/GA_Attribute.h>
#include <GA/GA_AttributeFilter.h>
#include <GA/GA_AIFCompare.h>
#include <GA/GA_ElementGroup.h>
#include <GA/GA_ElementWrangler.h>
#include <GA/GA_Handle.h>
#include <GA/GA_Range.h>
#include <GA/GA_Types.h>
#include <UT/UT_Interrupt.h>
#include <UT/UT_SmallArray.h>
#include <UT/UT_UniquePtr.h>
#include <SYS/SYS_Types.h>
#include <SYS/SYS_Math.h>

using namespace UT::Literal;

namespace HDK_Sample {

GA_Size
GEOsplitPoints(
    GEO_Detail *detail,
    const GA_ElementGroup *group)
{
    if (group && group->isEmpty())
        return 0;

    UT_AutoInterrupt boss("Making Unique Points");
    if (boss.wasInterrupted())
        return 0;

    // Behaviour is as if it's a point group if no group is present.
    GA_GroupType grouptype = GA_GROUP_POINT;
    const GA_PointGroup *point_group = nullptr;
    GA_PointGroupUPtr point_group_deleter;
    if (group)
    {
        grouptype = group->classType();
        if (grouptype == GA_GROUP_POINT)
            point_group = static_cast<const GA_PointGroup *>(group);
        else if (grouptype == GA_GROUP_VERTEX || grouptype == GA_GROUP_PRIMITIVE)
        {
            GA_PointGroup *ptgroup = new GA_PointGroup(*detail);
            point_group_deleter.reset(ptgroup);
            ptgroup->combine(group);
            point_group = ptgroup;
        }
    }

    GA_Size numpointsadded = 0;

    char bcnt = 0;

    UT_UniquePtr<GA_PointWrangler> ptwrangler(nullptr);

    UT_SmallArray<GA_Offset> vtxoffs;
    GA_Offset points_end = detail->getPointMap().lastOffset() + 1;
    GA_Offset start;
    GA_Offset end;
    for (GA_Iterator it(detail->getPointRange(point_group)); it.blockAdvance(start, end); )
    {
        // Prevent going beyond the original points; new points don't need to be split.
        if (start >= points_end)
            break;
        if (end > points_end)
            end = points_end;

        for (GA_Offset ptoff = start; ptoff < end; ++ptoff)
        {
            vtxoffs.setSize(0);

            // Make vertex order consistent, regardless of linked list order,
            // by sorting in vertex offset order
            bool has_other = false;
            if (grouptype == GA_GROUP_POINT)
            {
                for (GA_Offset vtxoff = detail->pointVertex(ptoff); GAisValid(vtxoff); vtxoff = detail->vertexToNextVertex(vtxoff))
                    vtxoffs.append(vtxoff);
            }
            else
            {
                for (GA_Offset vtxoff = detail->pointVertex(ptoff); GAisValid(vtxoff); vtxoff = detail->vertexToNextVertex(vtxoff))
                {
                    GA_Offset group_offset = vtxoff;
                    if (grouptype == GA_GROUP_PRIMITIVE)
                        group_offset = detail->vertexPrimitive(vtxoff);
                    if (group->contains(group_offset))
                        vtxoffs.append(vtxoff);
                    else
                        has_other = true;
                }
            }

            // If there's only one vertex in the group and none outside, nothing to split.
            // If there are no vertices in the group, also nothing to split.
            // Unique all but first vertex if all vertices of the point are in vtxoffs.
            GA_Size nvtx = vtxoffs.size();
            GA_Size points_to_add = nvtx - GA_Size(!has_other);
            if (points_to_add <= 0)
                continue;

            numpointsadded += points_to_add;

            if (!ptwrangler)
                ptwrangler.reset(new GA_PointWrangler(*detail, GA_AttributeFilter::selectPublic()));

            // TODO: This is not perfect; we should be sorting by primitive order
            //       and then vertex order within a primitive, so that results
            //       are the same whether the input was loaded from a file or
            //       computed.
            vtxoffs.sort();

            bool skip_first = !has_other;
            GA_Offset newptoff = detail->appendPointBlock(points_to_add);
            for (exint j = exint(skip_first); j < nvtx; ++j, ++newptoff)
            {
                if (!bcnt++ && boss.wasInterrupted())
                    return numpointsadded;

                ptwrangler->copyAttributeValues(newptoff, ptoff);
                detail->setVertexPoint(vtxoffs(j), newptoff);
            }
        }
    }
    if (numpointsadded > 0)
    {
        // If we'd only added/removed points, we could use
        // detail->bumpDataIdsForAddOrRemove(true, false, false),
        // but we also rewired vertices, so we need to bump the
        // linked-list topology attributes.
        detail->getAttributes().bumpAllDataIds(GA_ATTRIB_POINT);
        GA_ATITopology *topo = detail->getTopology().getPointRef();
        if (topo)
            topo->bumpDataId();
        topo = detail->getTopology().getVertexNextRef();
        if (topo)
            topo->bumpDataId();
        topo = detail->getTopology().getVertexPrevRef();
        if (topo)
            topo->bumpDataId();
        // Edge groups might also be affected, if any edges
        // were on points that were split, so we bump their
        // data IDs, just in case.
        detail->edgeGroups().bumpAllDataIds();
    }
    return numpointsadded;
}

namespace {
template<typename T>
bool
compareVertices(
    GA_Offset v1,
    GA_Offset v2,
    const GA_ROHandleT<T> &attrib,
    int tuplesize,
    fpreal tol)
{
    for (int i = 0; i < tuplesize; i++)
    {
        if (SYSabs(attrib.get(v1, i) - attrib.get(v2, i)) > tol)
            return false;
    }
    return true;
}

GA_Size
geoSplitPointsByAttrib(
    GEO_Detail *detail,
    const GA_Range &points,
    const GA_ElementGroup *group,
    const GA_Attribute *attrib,
    fpreal tolerance)
{
    // Point groups should be weeded out by the wrappers below.
    UT_ASSERT(!group || group->classType() == GA_GROUP_PRIMITIVE || group->classType() == GA_GROUP_VERTEX);
    bool is_primgroup = group && group->classType() == GA_GROUP_PRIMITIVE;

    GA_Size numpointsadded = 0;

    UT_ASSERT(attrib);
    if (!attrib)
        return numpointsadded;

    GA_AttributeOwner owner = attrib->getOwner();
    if (owner == GA_ATTRIB_POINT || owner == GA_ATTRIB_DETAIL)
        return numpointsadded;

    const GA_AIFCompare *compare = NULL;
    GA_ROHandleT<int64> attribi;
    GA_ROHandleR attribf;
    int tuplesize;
    const GA_ATINumeric *numeric = dynamic_cast<const GA_ATINumeric *>(attrib);
    if (numeric)
    {
        GA_StorageClass storeclass = attrib->getStorageClass();
        if (storeclass == GA_STORECLASS_INT)
        {
            attribi = attrib;
            UT_ASSERT(attribi.isValid());
            tuplesize = attribi.getTupleSize();
        }
        else if (storeclass == GA_STORECLASS_FLOAT)
        {
            attribf = attrib;
            UT_ASSERT(attribf.isValid());
            tuplesize = attribf.getTupleSize();
        }
        else
        {
            UT_ASSERT_MSG(0, "Why does a GA_ATINumeric have a storage class other than int or float?");
            compare = attrib->getAIFCompare();
        }
    }
    else
    {
        compare = attrib->getAIFCompare();
        if (compare == NULL)
        {
            UT_ASSERT_MSG(0, "Missing an implementation of GA_AIFCompare!");
            return numpointsadded;
        }
    }

    UT_UniquePtr<GA_PointWrangler> ptwrangler(nullptr);

    UT_SmallArray<GA_Offset> vtxlist;
    GA_Size initnumpts = detail->getNumPoints();
    for (GA_Iterator it(points); !it.atEnd(); ++it)
    {
        GA_Offset ptoff = *it;
        GA_Index ptidx = detail->pointIndex(ptoff);
        if (ptidx >= initnumpts)
            break; // New points are already split

        bool splitfound;
        do
        {
            GA_Offset vtxoff = detail->pointVertex(ptoff);
            if (!GAisValid(vtxoff))
                break; // Point doesn't belong to anyone

            // To avoid the results being dependent on the order of the
            // linked-list topology attribute, find the highest vertex offset
            // in the primitive of highest offset to be the base vertex.
            // Lowest would make more sense, but highest is more compatible with
            // the previous code.
            GA_Offset primoff = detail->vertexPrimitive(vtxoff);
            GA_Offset basevtxoff = GA_INVALID_OFFSET;
            GA_Offset baseprimoff = GA_INVALID_OFFSET;
            if (!group || group->contains(is_primgroup ? primoff : vtxoff))
            {
                basevtxoff = vtxoff;
                baseprimoff = primoff;
            }
            vtxoff = detail->vertexToNextVertex(vtxoff);
            while (GAisValid(vtxoff))
            {
                primoff = detail->vertexPrimitive(vtxoff);

                if (!group || group->contains(is_primgroup ? primoff : vtxoff))
                {
                    if (primoff > baseprimoff || (primoff == baseprimoff && vtxoff > basevtxoff))
                    {
                        basevtxoff = vtxoff;
                        baseprimoff = primoff;
                    }
                }
                vtxoff = detail->vertexToNextVertex(vtxoff);
            }

            if (!GAisValid(basevtxoff))
                break; // No vertices in group on current point

            // We have a vertex on the point that's in the group.
            // If any vertices mismatch, we make a new point.

            GA_Offset baseoffset = (owner == GA_ATTRIB_VERTEX) ? basevtxoff : baseprimoff;
            vtxlist.setSize(1);
            vtxlist(0) = basevtxoff;
            splitfound = false;
            for (vtxoff = detail->pointVertex(ptoff); GAisValid(vtxoff); vtxoff = detail->vertexToNextVertex(vtxoff))
            {
                if (vtxoff == basevtxoff)
                    continue;
                GA_Offset offset = (owner == GA_ATTRIB_VERTEX) ? vtxoff : detail->vertexPrimitive(vtxoff);
                bool match;
                if (attribi.isValid())
                    match = compareVertices<int64>(baseoffset, offset, attribi, tuplesize, tolerance);
                else if (attribf.isValid())
                    match = compareVertices<fpreal>(baseoffset, offset, attribf, tuplesize, tolerance);
                else
                {
                    bool success = compare->isEqual(match, *attrib, baseoffset, *attrib, offset);
                    if (!success)
                        match = true;
                }
                if (match)
                {
                    // Only append vertices in the group
                    if (!group || group->contains(is_primgroup ? detail->vertexPrimitive(vtxoff) : vtxoff))
                    {
                        vtxlist.append(vtxoff);
                    }
                }
                else
                {
                    // Split regardless of whether the unmatched vertex is in the group.
                    // This may or may not be the behaviour people expect,
                    // but it's ambiguous as to what people would expect.
                    // At least, if all vertices in the group have one value
                    // and all vertices out of the group have a different value,
                    // they probably want a new point, and that's accomplished
                    // with this condition.
                    splitfound = true;
                }
            }

            if (splitfound)
            {
                // A split has been found! Create a new point
                // using all the entries of vtxlist.
                GA_Offset newptoff = detail->appendPointOffset();
                ++numpointsadded;
                if (!ptwrangler)
                    ptwrangler.reset(new GA_PointWrangler(*detail, GA_AttributeFilter::selectPublic()));
                ptwrangler->copyAttributeValues(newptoff, ptoff);
                for (exint i = 0; i < vtxlist.size(); i++)
                    detail->setVertexPoint(vtxlist(i), newptoff);
            }
        } while (splitfound);
    }

    if (numpointsadded > 0)
    {
        // If we'd only added/removed points, we could use
        // detail->bumpDataIdsForAddOrRemove(true, false, false),
        // but we also rewired vertices, so we need to bump the
        // linked-list topology attributes.
        detail->getAttributes().bumpAllDataIds(GA_ATTRIB_POINT);
        GA_ATITopology *topo = detail->getTopology().getPointRef();
        if (topo)
            topo->bumpDataId();
        topo = detail->getTopology().getVertexNextRef();
        if (topo)
            topo->bumpDataId();
        topo = detail->getTopology().getVertexPrevRef();
        if (topo)
            topo->bumpDataId();
        // Edge groups might also be affected, if any edges
        // were on points that were split, so we bump their
        // data IDs, just in case.
        detail->edgeGroups().bumpAllDataIds();
    }
    return numpointsadded;
}
}

GA_Size
GEOsplitPointsByAttrib(
    GEO_Detail *detail,
    const GA_ElementGroup *group,
    const GA_Attribute *attrib,
    fpreal tolerance)
{
    bool isptgroup = (group == nullptr || group->getOwner() == GA_ATTRIB_POINT);
    return geoSplitPointsByAttrib(
        detail,
        detail->getPointRange(isptgroup ? UTverify_cast<const GA_PointGroup *>(group) : nullptr),
        isptgroup ? nullptr : group,
        attrib,
        tolerance);
}

GA_Size
GEOsplitPointsByAttrib(
    GEO_Detail *detail,
    const GA_Range &points,
    const GA_Attribute *attrib,
    fpreal tolerance)
{
    return geoSplitPointsByAttrib(
        detail,
        points,
        nullptr,
        attrib,
        tolerance);
}

} // End of HDK_Sample namespace