/*==LICENSE==*

CyanWorlds.com Engine - MMOG client, server and tools
Copyright (C) 2011  Cyan Worlds, Inc.

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
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(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.

Additional permissions under GNU GPL version 3 section 7

If you modify this Program, or any covered work, by linking or
combining it with any of RAD Game Tools Bink SDK, Autodesk 3ds Max SDK,
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(or a modified version of those libraries),
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 or by snail mail at:
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*==LICENSE==*/
//////////////////////////////////////////////////////////////////////////////
//                                                                          //
//  plDrawableSpans Class Export-only Functions                             //
//                                                                          //
//// Version History /////////////////////////////////////////////////////////
//                                                                          //
//  Created 4.3.2001 mcn                                                    //
//                                                                          //
//////////////////////////////////////////////////////////////////////////////

#include "HeadSpin.h"
#include "plDrawableSpans.h"
#include "hsStream.h"
#include "hsResMgr.h"
#include "plPipeline.h"
#include "plGeometrySpan.h"

#include "plSpaceTree.h"
#include "plSpaceTreeMaker.h"       // This is fun and amusing and wonderful to have here.
                                    // Keep it here forever.
#include "plSurface/hsGMaterial.h"
#include "plPipeline/plFogEnvironment.h"
#include "pnMessage/plRefMsg.h"
#include "pnMessage/plNodeRefMsg.h" // for NodeRefMsg
#include "plMessage/plDeviceRecreateMsg.h"
#include "plPipeline/plGBufferGroup.h"
#include "plSurface/hsGMaterial.h"
#include "plSurface/plLayerInterface.h"
#include "plGImage/plBitmap.h"
#include "plGLight/plLightInfo.h"
#include "plgDispatch.h"

#include "plStatusLog/plStatusLog.h"

//#define VERT_LOG

//// Write ///////////////////////////////////////////////////////////////////

void    plDrawableSpans::Write( hsStream* s, hsResMgr* mgr )
{
    uint32_t  i, j, count;
    
    // Make sure we're optimized before we write (should be tho)
//  Optimize();

    // Make sure all the garbage is cleaned up
    if( fNeedCleanup )
        IRemoveGarbage();

    // Parent write
    plDrawable::Write(s, mgr);

    s->WriteLE32( fProps );
    s->WriteLE32( fCriteria );
    s->WriteLE32( fRenderLevel.fLevel );

    /// Write out the material keys
    s->WriteLE32( fMaterials.GetCount() );
    for( i = 0; i < fMaterials.GetCount(); i++ )
        mgr->WriteKey( s, fMaterials[ i ] );

    /// Write out the icicles
    s->WriteLE32( fIcicles.GetCount() );
    for( i = 0; i < fIcicles.GetCount(); i++ )
        fIcicles[ i ].Write( s );

    /// Write out the patches
    // FIXME MAJOR VERSION
    // no more patches, remove this line
    s->WriteLE32(0);

    /// Write out the index table based on the pointer array
    count = fSpans.GetCount();
    s->WriteLE32( count );
    for( i = 0; i < count; i++ )
    {
        uint8_t   *icicle = (uint8_t *)fSpans[ i ], *base = (uint8_t *)fIcicles.AcquireArray();
        j = (uint32_t)( icicle - base ) / sizeof( plIcicle );
        s->WriteLE32( j );
    }

    /// Write out the common keys
    for( i = 0; i < count; i++ )
    {
        // The fog environ key
        mgr->WriteKey( s, fSpans[ i ]->fFogEnvironment );
    }

    /// Write out the bounds and stuff
    if( count > 0 )
    {
        fLocalBounds.Write(s);
        fWorldBounds.Write(s);
        fMaxWorldBounds.Write(s);
    }

    for( i = 0; i < count; i++ )
    {
        if( fSpans[i]->fProps & plSpan::kPropHasPermaLights )
        {
            uint32_t lcnt = fSpans[i]->fPermaLights.GetCount();
            s->WriteLE32(lcnt);
            int j;
            for( j = 0; j < lcnt; j++ )
                mgr->WriteKey( s, fSpans[i]->fPermaLights[j]);
        }
        if( fSpans[i]->fProps & plSpan::kPropHasPermaProjs )
        {
            uint32_t lcnt = fSpans[i]->fPermaProjs.GetCount();
            s->WriteLE32(lcnt);
            int j;
            for( j = 0; j < lcnt; j++ )
                mgr->WriteKey( s, fSpans[i]->fPermaProjs[j]);
        }
    }

    /// Write out the source spans if necessary
    s->WriteLE32( fSourceSpans.GetCount() );
    if( fSourceSpans.GetCount() > 0 )
    {
        for( i = 0; i < fSourceSpans.GetCount(); i++ )
            fSourceSpans[ i ]->Write( s );
    }

    count = fLocalToWorlds.GetCount();
    s->WriteLE32(count);
    for( i = 0; i < count; i++ )
    {
        fLocalToWorlds[i].Write(s);
        fWorldToLocals[i].Write(s);

        fLocalToBones[i].Write(s);
        fBoneToLocals[i].Write(s);
    }

    // Write out the drawInterface index arrays
    s->WriteLE32( fDIIndices.GetCount() );
    for( i = 0; i < fDIIndices.GetCount(); i++ )
    {
        plDISpanIndex   *array = fDIIndices[ i ];

        s->WriteLE32( array->fFlags );
        s->WriteLE32( array->GetCount() );
        for( j = 0; j < array->GetCount(); j++ )
            s->WriteLE32( (*array)[ j ] );
    }

    // Write the groups out
    count = fGroups.GetCount();

    s->WriteLE( count );
    for( i = 0; i < count; i++ )
    {
#ifdef VERT_LOG

        hsUNIXStream log;
        log.Open("log\\GBuf.log", "ab");
        char buf[256];
        sprintf(buf, "Drawable Span: %s, GroupNum: %u\r\n", GetKeyName(), i);
        log.WriteString(buf);
        log.Close();
#endif
        fGroups[ i ]->Write( s );
    }

    /// Other stuff
    mgr->WriteCreatable(s, fSpaceTree);

    mgr->WriteKey(s, fSceneNode);

    /// All done!
}

//// AddDISpans //////////////////////////////////////////////////////////////
//  Adds a drawInterface's geometry spans to the list to be collapsed into 
//  buffers.

uint32_t  plDrawableSpans::AddDISpans( hsTArray<plGeometrySpan *> &spans, uint32_t index )
{
    int             i;
    uint32_t          spanIdx;
    plSpan          *span;
    hsBounds3Ext    bounds;


    /// Do garbage cleanup first
    if( fNeedCleanup )
        IRemoveGarbage();

    if (index == (uint32_t)-1) // need a new one
    {
        /// Create a lookup entry
        index = fDIIndices.GetCount();
        fDIIndices.Append( new plDISpanIndex );
        fDIIndices[ index ]->fFlags = plDISpanIndex::kNone;
    }
    plDISpanIndex   *spanLookup = fDIIndices[ index ];


    /// Add the geometry spans to our list. Also add our internal span
    /// copies
    for( i = 0; i < spans.GetCount(); i++ )
    {
        spanLookup->Append( fSourceSpans.GetCount() );
        spans[ i ]->fSpanRefIndex = fSourceSpans.GetCount();
        fSourceSpans.Append( spans[ i ] );  

        spanIdx = fIcicles.GetCount();
        fIcicles.Append( plIcicle() );
        plIcicle *icicle = &fIcicles[ spanIdx ];
        span = (plSpan *)icicle;

        /// Set common stuff
        IAssignMatIdxToSpan( span, spans[ i ]->fMaterial );
        span->fLocalToWorld = spans[ i ]->fLocalToWorld;
        span->fWorldToLocal = spans[ i ]->fWorldToLocal;
        span->fProps |= ( spans[ i ]->fProps & plGeometrySpan::kPropRunTimeLight ) ? plSpan::kPropRunTimeLight : 0;
        if( spans[i]->fProps & plGeometrySpan::kPropNoShadowCast )
            span->fProps |= plSpan::kPropNoShadowCast;
        if( spans[i]->fProps & plGeometrySpan::kPropNoShadow )
            span->fProps |= plSpan::kPropNoShadow;
        if( spans[i]->fProps & plGeometrySpan::kPropForceShadow )
            span->fProps |= plSpan::kPropForceShadow;
        if( spans[i]->fProps & plGeometrySpan::kPropReverseSort )
            span->fProps |= plSpan::kPropReverseSort;
        if( spans[i]->fProps & plGeometrySpan::kPartialSort )
            span->fProps |= plSpan::kPartialSort;
        if( spans[i]->fProps & plGeometrySpan::kVisLOS )
        {
            span->fProps |= plSpan::kVisLOS;
            fProps |= plDrawable::kPropHasVisLOS;
        }

        span->fNumMatrices = spans[ i ]->fNumMatrices;
        span->fBaseMatrix = spans[ i ]->fBaseMatrix;
        span->fLocalUVWChans = spans[i]->fLocalUVWChans;
        span->fMaxBoneIdx = spans[i]->fMaxBoneIdx;
        span->fPenBoneIdx = (uint16_t)(spans[i]->fPenBoneIdx);

        bounds = spans[ i ]->fLocalBounds;
        span->fLocalBounds = bounds;
        bounds.Transform( &span->fLocalToWorld );
        span->fWorldBounds = bounds;
        span->fFogEnvironment = spans[ i ]->fFogEnviron;

        /// Add to our source indices
        fSpans.Append( span );
        fSpanSourceIndices.Append( spanIdx );
    }

    /// Rebuild the pointer array
    IRebuildSpanArray();

    SetSpaceTree(nil);

    fOptimized = false;

    return index;
}

//// Optimize ////////////////////////////////////////////////////////////////

void    plDrawableSpans::Optimize( void )
{
    int     i;

    if( fOptimized )
        return;

    /// Sort all the source spans
    if( !(fProps & kPropNoReSort) )
        ISortSourceSpans();

    /// Pack the source spans into spans and indices
    IPackSourceSpans();

    /// Now that we're done with the source spans, get rid of them! (BLEAH!)
    for( i = 0; i < fSourceSpans.GetCount(); i++ )
        delete fSourceSpans[ i ];
    fSourceSpans.Reset();

    if( fCriteria & kCritSortSpans )
    {
        if( !(fProps & kPropNoReSort) )
            fProps |= kPropSortSpans;
    }
    if( fCriteria & kCritSortFaces )
    {
        fProps |= kPropSortFaces;
    }

    /// Now we do a pass at the buffer groups, asking them to tidy up
    for( i = 0; i < fGroups.GetCount(); i++ )
        fGroups[ i ]->TidyUp();

    // Look to see if we have any materials we aren't using anymore.
    for( i = 0; i < fMaterials.GetCount(); i++ )
    {
        ICheckToRemoveMaterial(i);
    }

    fReadyToRender = false;

    // Make the space tree (hierarchical bounds).
    plSpaceTreeMaker maker;
    maker.Reset();
    for( i = 0; i < GetNumSpans(); i++ )
    {
        maker.AddLeaf( fSpans[ i ]->fWorldBounds, fSpans[ i ]->fProps & plSpan::kPropNoDraw  );
    }
    plSpaceTree* tree = maker.MakeTree();
    SetSpaceTree(tree);

    /// All done!
    fOptimized = true;
}

static plStatusLog* IStartLog(const char* name, int numSpans)
{
    static char buff[256];
    sprintf(buff, "x%s.log", name);

    plStatusLog* statusLog = plStatusLogMgr::GetInstance().CreateStatusLog(
        plStatusLogMgr::kDefaultNumLines, 
        buff, 
        plStatusLog::kFilledBackground | plStatusLog::kDeleteForMe );
    return statusLog;
}

static plStatusLog* IEndLog(plStatusLog* statusLog)
{
    delete statusLog;
    return nil;
}

static void ILogSpan(plStatusLog* statusLog, plGeometrySpan* geo, plVertexSpan* span, plGBufferGroup* group)
{
    if( span->fTypeMask & plSpan::kIcicleSpan )
    {
        plIcicle* ice = (plIcicle*)span;
        if( geo->fProps & plGeometrySpan::kFirstInstance )
        {
            plGBufferCell* cell = group->GetCell(span->fVBufferIdx, span->fCellIdx);
            uint32_t stride = group->GetVertexSize();
            uint32_t ptr = cell->fVtxStart + span->fCellOffset * stride;

            statusLog->AddLineF("From obj <%s> mat <%s> size %d bytes grp=%d (%d offset)",
                geo->fMaxOwner.s_str("<unknown>"),
                geo->fMaterial ? geo->fMaterial->GetKey()->GetName().c_str() : "<unknown>",
                geo->GetVertexSize(geo->fFormat) * geo->fNumVerts + sizeof(uint16_t) * geo->fNumIndices,
                span->fGroupIdx,
                ptr
                );
//              span->fVBufferIdx,
//              span->fCellIdx,
//              span->fCellOffset,
//              span->fVStartIdx,
//              span->fVLength,
//              ice->fIBufferIdx,
//              ice->fIStartIdx,
//              ice->fILength
        }
        else
        {
            statusLog->AddLineF("Instanced obj <%s> mat <%s> grp=%d (%d/%d/%d/%d/%d/%d/%d/%d)",
                geo->fMaxOwner.s_str("<unknown>"),
                geo->fMaterial ? geo->fMaterial->GetKey()->GetName().c_str() : "<unknown>",
                span->fGroupIdx,
                span->fVBufferIdx,
                span->fCellIdx,
                span->fCellOffset,
                span->fVStartIdx,
                span->fVLength,
                ice->fIBufferIdx,
                ice->fIStartIdx,
                ice->fILength
                );
        }
    }
    else
    {
        if( geo->fProps & plGeometrySpan::kFirstInstance )
        {
            statusLog->AddLineF("From obj <%s> mat <%s> size %d bytes grp=%d (%d/%d/%d/%d/%d)",
                geo->fMaxOwner.s_str("<unknown>"),
                geo->fMaterial ? geo->fMaterial->GetKey()->GetName().c_str() : "<unknown>",
                geo->GetVertexSize(geo->fFormat) * geo->fNumVerts + sizeof(uint16_t) * geo->fNumIndices,
                span->fGroupIdx,
                span->fVBufferIdx,
                span->fCellIdx,
                span->fCellOffset,
                span->fVStartIdx,
                span->fVLength
                );
        }
        else
        {
            statusLog->AddLineF("Instanced obj <%s> mat <%s> grp=%d (%d/%d/%d/%d/%d)",
                geo->fMaxOwner.s_str("<unknown>"),
                geo->fMaterial ? geo->fMaterial->GetKey()->GetName().c_str() : "<unknown>",
                span->fGroupIdx,
                span->fVBufferIdx,
                span->fCellIdx,
                span->fCellOffset,
                span->fVStartIdx,
                span->fVLength
                );
        }
    }
}

//// IPackSourceSpans ////////////////////////////////////////////////////////
//  Takes the array of source spans and converts them to our internal icicle
//  spans, vertex buffers and index buffers.

void    plDrawableSpans::IPackSourceSpans( void )
{
    int             i, j;
    hsBounds3Ext    bounds;
    hsBitVector     doneSpans;


    /// Calc bounds
    fLocalBounds.MakeEmpty();
    fWorldBounds.MakeEmpty();

    for( i = 0; i < fSourceSpans.GetCount(); i++ )
    {
        hsBounds3Ext    bnd = fSourceSpans[ i ]->fLocalBounds;
        bnd.Transform( &fSourceSpans[ i ]->fLocalToWorld );
        fWorldBounds.Union( &bnd );
    }

    fLocalBounds = fWorldBounds;
    fLocalBounds.Transform( &fWorldToLocal );
    fMaxWorldBounds = fWorldBounds;

    // It could be that instance refs in spans that we (the drawable) own
    // are actually spans in some other drawable. That's not currently handled.
    // (Making that case handled would involve rewriting the instancing implementation
    // to not suck ass).
    // So for each instance set, we make two lists of instance refs, the ones also
    // in this drawable (refsHere), and ones not (refsThere). If there are refsThere,
    // we split out the refsHere into a new instance group, removing them from the
    // refsThere list. If refsThere still contains spans from separate drawables, 
    // that will be dealt with in those drawables' Optimize calls.
    doneSpans.Clear();
    for( i = 0; i < fSourceSpans.GetCount(); i++ )
    {
        if( !doneSpans.IsBitSet(i) )
        {
            plGeometrySpan* span = fSourceSpans[i];
            if( span->fInstanceRefs )
            {
                hsTArray<plGeometrySpan*>& refs = *(span->fInstanceRefs);
                hsTArray<plGeometrySpan*> refsHere;
                hsTArray<plGeometrySpan*> refsThere;

                int k;
                for( k = 0; k < refs.GetCount(); k++ )
                {
                    plGeometrySpan* other = refs[k];
                    if( other != span )
                    {
                        int idx = fSourceSpans.Find(other);
                        if( fSourceSpans.kMissingIndex == idx )
                        {
                            refsThere.Append(other);
                        }
                        else
                        {
                            refsHere.Append(other);
                        }
                    }
                }
                if( refsThere.GetCount() )
                {
                    if( refsHere.GetCount() )
                    {
                        span->BreakInstance();

                        // Okay, got to form a new instance group out of refsHere.
                        for( k = 0; k < refsHere.GetCount(); k++ )
                        {
                            plGeometrySpan* other = refsHere[k];

                            other->ChangeInstance(span);

                            doneSpans.SetBit(other->fSpanRefIndex);
                        }
                    }
                    else
                    {
                        span->UnInstance();
                    }
                    if( refsThere.GetCount() == 1 )
                    {
                        refsThere[0]->UnInstance();
                    }
                }
            }
            doneSpans.SetBit(i);
        }
    }

    /// Now pack the spans
    doneSpans.Clear();
    for( i = 0; i < fSourceSpans.GetCount(); i++ )
    {
        // Now we fill the rest of the data in for our span
        if( !doneSpans.IsBitSet( i ) )
        {
            if( fSourceSpans[ i ]->fProps & plGeometrySpan::kInstanced )
            {
                // Instanced spans--convert the first as normal, then convert the rest
                // using the first as reference
                doneSpans.SetBit( i, true );

                plIcicle    *baseIcicle = (plIcicle *)fSpans[ i ];
                IConvertGeoSpanToIcicle( fSourceSpans[ i ], baseIcicle, 0, baseIcicle );

                // Loop through the rest
                for( j = 0; j < fSourceSpans[ i ]->fInstanceRefs->GetCount(); j++ )
                {
                    plGeometrySpan *other = (*fSourceSpans[ i ]->fInstanceRefs)[ j ];
                    if( other == fSourceSpans[ i ] )
                        continue;

#if 0 // What exactly is this supposed to be doing? My guess is, NADA.
                    if( IConvertGeoSpanToIcicle( other, (plIcicle *)fSpans[ other->fSpanRefIndex ], 0, baseIcicle ) )
                        baseIcicle = (plIcicle *)fSpans[ other->fSpanRefIndex ];
#else // What exactly is this supposed to be doing? My guess is, NADA.
                    IConvertGeoSpanToIcicle( other, (plIcicle *)fSpans[ other->fSpanRefIndex ], 0, baseIcicle );
#endif // What exactly is this supposed to be doing? My guess is, NADA.
                    doneSpans.SetBit( other->fSpanRefIndex, true );
                }
    
            }
            else
            {
                // Do normal, uninstanced conversion
                IConvertGeoSpanToIcicle( fSourceSpans[ i ], (plIcicle *)fSpans[ i ], 0 );   
                doneSpans.SetBit( i, true );
            }
        }
    }

#ifdef VERT_LOG
    hsTArray<plGeometrySpan*> order;
    order.SetCount(fSourceSpans.GetCount());
    for( i = 0; i < fSourceSpans.GetCount(); i++ )
    {
        order[fSourceSpans[i]->fSpanRefIndex] = fSourceSpans[i];
    }

    plStatusLog* statusLog = IStartLog(GetKey()->GetName(), fSourceSpans.GetCount());
    for( i = 0; i < order.GetCount(); i++ )
    {
        plVertexSpan* vSpan = (plVertexSpan*)fSpans[i];
        ILogSpan(statusLog, order[i], vSpan, fGroups[vSpan->fGroupIdx]);
    }
    statusLog = IEndLog(statusLog);
#endif
}

//// ISortSourceSpans ////////////////////////////////////////////////////////
//  Does our actual optimization path by resorting all the spans into the
//  most efficient order possible. Also has to re-order the span lookup
//  table.

void    plDrawableSpans::ISortSourceSpans( void )
{
    hsTArray<uint32_t>    spanReorderTable, spanInverseTable;
    int                 i, j, idx;
    plGeometrySpan      *tmpSpan;
    uint32_t              tmpIdx;
    plSpan              *tmpSpanPtr;


    // Init the reorder table
    for( i = 0; i < fSourceSpans.GetCount(); i++ )
        spanReorderTable.Append( i );

    // Do a nice, if naiive, sort by material (hehe by the pointers, no less)
    for( i = 0; i < fSourceSpans.GetCount() - 1; i++ )
    {
        for( j = i + 1, idx = i; j < fSourceSpans.GetCount(); j++ )
        {
            if( ICompareSpans( fSourceSpans[ j ], fSourceSpans[ idx ] ) < 0 )
                idx = j;
        }

        // Swap idx with i, so we get the smallest pointer on top
        if( i != idx )
        {
            // Swap both the source span and our internal span
            tmpSpan = fSourceSpans[ i ];
            fSourceSpans[ i ] = fSourceSpans[ idx ];
            fSourceSpans[ idx ] = tmpSpan;

            fSourceSpans[ i ]->fSpanRefIndex = i;
            fSourceSpans[ idx ]->fSpanRefIndex = idx;

            tmpSpanPtr = fSpans[ i ];
            fSpans[ i ] = fSpans[ idx ];
            fSpans[ idx ] = tmpSpanPtr;

            // Also swap the entries in the reorder table
            tmpIdx = spanReorderTable[ i ];
            spanReorderTable[ i ] = spanReorderTable[ idx ];
            spanReorderTable[ idx ] = tmpIdx;
        }

        // Next!
    }


    /// Problem: our reorder table is inversed(y->x instead of x->y). Either we search for numbers,
    /// or we just flip it first...
    spanInverseTable.SetCountAndZero( spanReorderTable.GetCount() );
    for( i = 0; i < spanReorderTable.GetCount(); i++ )
        spanInverseTable[ spanReorderTable[ i ] ] = i;

    /// Now update our span xlate table
    for( i = 0; i < fDIIndices.GetCount(); i++ )
    {
        if( !fDIIndices[ i ]->IsMatrixOnly() )
        {
            for( j = 0; j < fDIIndices[ i ]->GetCount(); j++ )
            {
                idx = (*fDIIndices[ i ])[ j ];

                (*fDIIndices[ i ])[ j ] = spanInverseTable[ idx ];
            }
        }
    }

    /// Use our pointer array to rebuild the icicle array (UUUUGLY)
    hsTArray<plIcicle>      tempIcicles;
    plIcicle                *newIcicle;

    tempIcicles.SetCount( fIcicles.GetCount() );

    for( i = 0, newIcicle = tempIcicles.AcquireArray();
         i < fSpans.GetCount(); i++ )
    {
        *newIcicle = *( (plIcicle *)fSpans[ i ] );
        fSpans[ i ] = newIcicle;
        newIcicle++;    
    }

    /// Swap the two arrays out. This will basically swap the actual memory blocks, so be careful...
    fIcicles.Swap( tempIcicles );
    tempIcicles.Reset();
}

//// ICompareSpans ///////////////////////////////////////////////////////////
//  Sorting function for ISortSpans(). Kinda like strcmp(): returns -1 if 
//  span1 < span2, 1 if span1 > span2, 0 if "equal".

short   plDrawableSpans::ICompareSpans( plGeometrySpan *span1, plGeometrySpan *span2 )
{
    hsBool      b1, b2;
    int         i, j, numLayers;
    plBitmap    *t1, *t2;


    /// Quick check--identical materials are easy to compare :)
    if( span1->fMaterial == span2->fMaterial )
        return 0;

    /// Compare features from most to least important...

    // Any decal span should come after a non-decal
    if( span1->fDecalLevel < span2->fDecalLevel )
        return -1;
    if( span1->fDecalLevel > span2->fDecalLevel )
        return 1;
    // Ok, they're equal decal-wise, so find something else to judge on

    // Most important: is one of the materials an alpha blend? (if so, gotta
    // put at end, so it's "bigger")
    if( span1->fMaterial->GetNumLayers() > 0 && 
        ( span1->fMaterial->GetLayer( 0 )->GetState().fBlendFlags & hsGMatState::kBlendMask ) != 0 )
        b1 = true;
    else
        b1 = false;

    if( span2->fMaterial->GetNumLayers() > 0 && 
        ( span2->fMaterial->GetLayer( 0 )->GetState().fBlendFlags & hsGMatState::kBlendMask ) != 0 )
        b2 = true;
    else
        b2 = false;

    if( b1 != b2 )
        return( b1 ? 1 : -1 );

    // Next is texture (name). We do this kinda like strings: compare the first layer's
    // textures and go upwards, so that we group materials together starting with the
    // base layer's texture and going upwards
    numLayers = span1->fMaterial->GetNumLayers();
    if( span2->fMaterial->GetNumLayers() < numLayers )
        numLayers = span2->fMaterial->GetNumLayers();

    for( i = 0; i < numLayers; i++ )
    {
        t1 = span1->fMaterial->GetLayer( i )->GetTexture();
        t2 = span2->fMaterial->GetLayer( i )->GetTexture();

        if( t1 != nil && t2 == nil )
            return 1;
        else if( t1 == nil && t2 != nil )
            return -1;
        else if( t1 == nil && t2 == nil )
            break;  // Textures equal up to here--keep going with rest of tests
        
        if( !t1->GetKeyName().IsNull() && !t2->GetKeyName().IsNull() )
        {
            j = t1->GetKeyName().Compare( t2->GetKeyName(), plString::kCaseInsensitive );
            if( j != 0 )
                return (short)j;
        }
    }

    // Finally, by material itself.
    if( !span1->fMaterial->GetKeyName().IsNull() && !span2->fMaterial->GetKeyName().IsNull() )
    {
        j = span1->fMaterial->GetKeyName().Compare( span2->fMaterial->GetKeyName(), plString::kCaseInsensitive );
        if( j != 0 )
            return (short)j;
    }

    if( span1->fLocalToWorld.fFlags != span2->fLocalToWorld.fFlags )
    {
        if( span1->fLocalToWorld.fFlags )
            return -1;
        else
            return 1;
    }

    /// Equal in our book...
    return 0;
}
