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# PtexImporter/ptex/PtexFilterKernel.cpp

    /*
    PTEX SOFTWARE
    Copyright 2009 Disney Enterprises, Inc.  All rights reserved

    Redistribution and use in source and binary forms, with or without
    modification, are permitted provided that the following conditions are
    met:

      * Redistributions of source code must retain the above copyright
        notice, this list of conditions and the following disclaimer.

      * Redistributions in binary form must reproduce the above copyright
        notice, this list of conditions and the following disclaimer in
        the documentation and/or other materials provided with the
        distribution.

      * The names "Disney", "Walt Disney Pictures", "Walt Disney Animation
        Studios" or the names of its contributors may NOT be used to
        endorse or promote products derived from this software without
        specific prior written permission from Walt Disney Pictures.

    Disclaimer: THIS SOFTWARE IS PROVIDED BY WALT DISNEY PICTURES AND
    CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING,
    BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS
    FOR A PARTICULAR PURPOSE, NONINFRINGEMENT AND TITLE ARE DISCLAIMED.
    IN NO EVENT SHALL WALT DISNEY PICTURES, THE COPYRIGHT HOLDER OR
    CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
    EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
    PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
    PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND BASED ON ANY
    THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
    (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
    OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
    */

    #include "PtexFilterContext.h"
    #include "PtexFilterKernel.h"
    #include "PtexHalf.h"

    /* Kernel iterator

       Allows moving through the kernel while moving through the data
       following the in-memory order of the data.  Since the kernel may be
       rotated with respect to the data, the iterator allows moving
       through the kernel in arbitrary order which is accomplished by
       having both a ustride and a vstride, either of which may be
       positive or negative.
    */

    class PtexFilterKernel::Iter : public Ptex {
     public:
        const PtexFilterContext& ctx;

        int ustride;        // distance between u samples
        int vstride;        // distance between v samples
        int rowskip;        // distance to skip at end of row
        double* pos;        // current iterator pos
        double* rowend;     // end of current iterator row
        double* end;        // end of current iterator

        int dstart;         // offset to start of data
        int drowskip;       // amount of data to skip at end of row

        Iter(const PtexFilterKernel& k, int rotate, const PtexFilterContext& c)
        : ctx(c)
        {
        int resu = k.res.u(), resv = k.res.v();
        switch (rotate) {
        case 0: // no rotation
            ustride = 1;
            vstride = k.stride;
            pos = k.start;
            rowend = pos + k.uw;
            end = pos + vstride * k.vw;
            dstart = k.v * resu + k.u;
            drowskip = resu - k.uw;
            break;

        case 1: // rotate kernel 90 deg cw relative to data
            ustride = -k.stride;
            vstride = 1;
            pos = k.start + k.stride * (k.vw-1);
            rowend = k.start - k.stride;
            end = pos + k.uw;
            dstart = k.u * resv + (resv - k.vw - k.v);
            drowskip = resv - k.vw;
            break;

        case 2: // rotate kernel 180 deg cw relative to data
            ustride = -1;
            vstride = -k.stride;
            pos = k.start + k.stride * (k.vw-1) + k.uw-1;
            rowend = pos - k.uw;
            end = pos + vstride * k.vw;
            dstart = (resv - k.vw - k.v) * resu + (resu - k.uw - k.u);
            drowskip = resu - k.uw;
            break;

        case 3: // rotate kernel 90 deg ccw relative to data
            ustride = k.stride;
            vstride = -1;
            pos = k.start + k.uw-1;
            rowend = pos + k.vw * k.stride;
            end = pos - k.uw;
            dstart = (resu - k.uw - k.u) * resv + k.v;
            drowskip = resv - k.vw;
            break;
        }
        rowskip = int(pos - rowend) + vstride;
        dstart = dstart * c.ntxchannels + c.firstchan;
        drowskip *= c.ntxchannels;
        }

        double nextval()
        {
        double result = *pos;
        pos += ustride;
        return result;
        }

        bool rowdone()
        {
        if (pos != rowend) return 0;
        rowend += vstride;
        pos += rowskip;
        return 1;
        }

        bool done()
        {
        return pos == end;
        }
    };

    class PtexFilterKernel::TileIter : public Ptex
    {
     public:
        PtexFilterKernel kernels[4];  // kernel split over tiles
        int tiles[4];         // tiles covered by kernel
        int ntiles;           // number of tiles
        int index;            // current index

        TileIter(const PtexFilterKernel& k, int rotate, Res tileres)
        : index(0)
        {
        // find first tile (ignoring rotation for now)
        int tileu = k.u >> tileres.ulog2;
        int tilev = k.v >> tileres.vlog2;
        int ntilesu = k.res.ntilesu(tileres);
        int ntilesv = k.res.ntilesv(tileres);

        // find updated u, v within first tile
        int u = k.u - tileu * tileres.u();
        int v = k.v - tilev * tileres.v();

        // set primary kernel entry and tile offsets
        kernels[0].set(tileres, u, v, k.uw, k.vw, k.start, k.stride);
        int tilesu[4], tilesv[4];
        tilesu[0] = tileu; tilesv[0] = tilev;
        ntiles = 1;

        // split kernel across tile boundaries into (up to) 4 pieces
        PtexFilterKernel ku, kv, kc;
        kernels[0].split(ku, kv, kc);
        if (ku) {
            kernels[ntiles] = ku;
            tilesu[ntiles] = tileu + 1;
            tilesv[ntiles] = tilev;
            ntiles++;
        }
        if (kv) {
            kernels[ntiles] = kv;
            tilesu[ntiles] = tileu;
            tilesv[ntiles] = tilev + 1;
            ntiles++;
        }
        if (kc) {
            kernels[ntiles] = kc;
            tilesu[ntiles] = tileu + 1;
            tilesv[ntiles] = tilev + 1;
            ntiles++;
        }

        // calculate (rotated) tile indices
        switch (rotate) {
        default:
        case 0: // no rotation
            for (int i = 0; i < ntiles; i++)
            tiles[i] = tilesv[i] * ntilesu + tilesu[i];
            break;
        case 1: // rotate kernel 90 deg cw relative to data
            for (int i = 0; i < ntiles; i++)
            tiles[i] = tilesu[i] * ntilesv + (ntilesv - 1 - tilesv[i]);
            break;
        case 2: // rotate kernel 180 deg cw relative to data
            for (int i = 0; i < ntiles; i++)
            tiles[i] = (ntilesv - 1 - tilesv[i]) * ntilesu
                + (ntilesu - 1 - tilesu[i]);
            break;
        case 3: // rotate kernel 90 deg ccw relative to data
            for (int i = 0; i < ntiles; i++)
            tiles[i] = (ntilesu - 1 - tilesu[i]) * ntilesv + tilesv[i];
            break;
        }
        }

        int tile() { return tiles[index]; }
        const PtexFilterKernel& kernel() { return kernels[index]; }
        bool next() { return ++index < ntiles; }
    };

    void PtexFilterKernel::split(PtexFilterKernel& ku, PtexFilterKernel& kv,
                     PtexFilterKernel& kc)
    {
        // split off adjacent u, v, and corner pieces from kernel
        if (u < 0)                { splitL(ku); }
        else if (u+uw > res.u()) { splitR(ku); }
        if (v < 0)                { splitB(kv); if (ku) ku.splitB(kc); }
        else if (v+vw > res.v()) { splitT(kv); if (ku) ku.splitT(kc); }

        // for corner, set eid to edge leading in to corner (counterclockwise)
        if (kc) kc.eid = ((ku.eid+1)%4 == kv.eid) ? ku.eid : kv.eid;
    }

    namespace {
        // fixed length accumulator: result[i] += val[i] * weight
        template<typename T, int n>
        struct VecAccum {
        VecAccum() {}
        void operator()(float* result, const T* val, double weight)
        {
            *result = float(*result + *val * weight);
            // use template to unroll loop
            VecAccum<T,n-1>()(result+1, val+1, weight);
        }
        };

        // loop terminator
        template<typename T>
        struct VecAccum<T,0> { void operator()(float*, const T*, double) {} };

        // variable length accumulator: result[i] += val[i] * weight
        template<typename T>
        struct VecAccumN {
        void operator()(float* result, const T* val, int nchan, double weight)
        {
            for (int i = 0; i < nchan; i++)
            result[i] = float(result[i] + val[i] * weight);
        }
        };

        template<typename T>
        inline void ApplyConstT(void* data, const PtexFilterContext& c, double weight)
        {
        VecAccumN<T>()(c.result, ((T*)data)+c.firstchan, c.nchannels, weight);
        }

        inline void ApplyConst(void* data, const PtexFilterContext& c, double weight)
        {
        switch (c.dt) {
        case Ptex::dt_uint8:   ApplyConstT<uint8_t> (data, c, weight); break;
        case Ptex::dt_uint16:  ApplyConstT<uint16_t>(data, c, weight); break;
        case Ptex::dt_half:    ApplyConstT<PtexHalf>(data, c, weight); break;
        case Ptex::dt_float:   ApplyConstT<float>   (data, c, weight); break;
        }
        }

        template<typename T, int n>
        inline void ApplyT(void* data, PtexFilterKernel::Iter& i)
        {
        T* ptr = ((T*)data) + i.dstart;
        float* result = i.ctx.result;
        int ntxchan = i.ctx.ntxchannels;
        VecAccum<T,n> accum;
        do {
            do {
            accum(result, ptr, i.nextval());
            ptr += ntxchan;
            } while (!i.rowdone());
            ptr += i.drowskip;
        } while(!i.done());
        }

        template<typename T>
        inline void ApplyT(void* data, PtexFilterKernel::Iter& i)
        {
        T* ptr = ((T*)data) + i.dstart;
        float* result = i.ctx.result;
        int nchan = i.ctx.nchannels;
        int ntxchan = i.ctx.ntxchannels;
        VecAccumN<T> accum;
        do {
            do {
            accum(result, ptr, nchan, i.nextval());
            ptr += ntxchan;
            } while (!i.rowdone());
            ptr += i.drowskip;
        } while(!i.done());
        }

        inline void Apply(void* data, PtexFilterKernel::Iter& i)
        {
        switch((i.ctx.nchannels-1)<<2|i.ctx.dt) {
        case (0<<2|Ptex::dt_uint8):  ApplyT<uint8_t, 1>(data, i); break;
        case (0<<2|Ptex::dt_uint16): ApplyT<uint16_t,1>(data, i); break;
        case (0<<2|Ptex::dt_half):   ApplyT<PtexHalf,1>(data, i); break;
        case (0<<2|Ptex::dt_float):  ApplyT<float,   1>(data, i); break;
        case (1<<2|Ptex::dt_uint8):  ApplyT<uint8_t, 2>(data, i); break;
        case (1<<2|Ptex::dt_uint16): ApplyT<uint16_t,2>(data, i); break;
        case (1<<2|Ptex::dt_half):   ApplyT<PtexHalf,2>(data, i); break;
        case (1<<2|Ptex::dt_float):  ApplyT<float,   2>(data, i); break;
        case (2<<2|Ptex::dt_uint8):  ApplyT<uint8_t, 3>(data, i); break;
        case (2<<2|Ptex::dt_uint16): ApplyT<uint16_t,3>(data, i); break;
        case (2<<2|Ptex::dt_half):   ApplyT<PtexHalf,3>(data, i); break;
        case (2<<2|Ptex::dt_float):  ApplyT<float,   3>(data, i); break;
        case (3<<2|Ptex::dt_uint8):  ApplyT<uint8_t, 4>(data, i); break;
        case (3<<2|Ptex::dt_uint16): ApplyT<uint16_t,4>(data, i); break;
        case (3<<2|Ptex::dt_half):   ApplyT<PtexHalf,4>(data, i); break;
        case (3<<2|Ptex::dt_float):  ApplyT<float,   4>(data, i); break;
        default:
            switch (i.ctx.dt) {
            case Ptex::dt_uint8:  ApplyT<uint8_t> (data, i); break;
            case Ptex::dt_uint16: ApplyT<uint16_t>(data, i); break;
            case Ptex::dt_half:   ApplyT<PtexHalf>(data, i); break;
            case Ptex::dt_float:  ApplyT<float>   (data, i); break;
            }
        }
        }
    }

    void PtexFilterKernel::apply(int faceid, int rotate, const PtexFilterContext& c) const
    {
        PtexPtr<PtexFaceData> dh ( c.tx->getData(faceid, (rotate & 1) ? res.swappeduv() : res) );
        if (!dh) return;

        if (dh->isConstant()) {
        ApplyConst(dh->getData(), c, totalWeight());
        }
        else if (dh->isTiled()) {
        Res tres = dh->tileRes();
        TileIter tileiter(*this, rotate, (rotate & 1) ? tres.swappeduv() : tres);
        do {
            PtexPtr<PtexFaceData> th ( dh->getTile(tileiter.tile()) );
            if (th->isConstant()) {
            ApplyConst(th->getData(), c, tileiter.kernel().totalWeight());
            }
            else {
            Iter iter(tileiter.kernel(), rotate, c);
            Apply(th->getData(), iter);
            }
        } while (tileiter.next());
        }
        else {
        Iter iter(*this, rotate, c);
        Apply(dh->getData(), iter);
        }
    }

    void PtexFilterKernel::applyConst(void* data, const PtexFilterContext& c, double weight)
    {
        ApplyConst(data, c, weight);
    }