/**
 * @file llvograss.cpp
 * @brief Not a blade, but a clump of grass
 *
 * $LicenseInfo:firstyear=2001&license=viewerlgpl$
 * Second Life Viewer Source Code
 * Copyright (C) 2010, Linden Research, Inc.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation;
 * version 2.1 of the License only.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 *
 * Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
 * $/LicenseInfo$
 */

#include "llviewerprecompiledheaders.h"

#include "llvograss.h"

#include "llviewercontrol.h"

#include "llagentcamera.h"
#include "llnotificationsutil.h"
#include "lldrawable.h"
#include "lldrawpoolalpha.h"
#include "llface.h"
#include "llsky.h"
#include "llsurface.h"
#include "llsurfacepatch.h"
#include "llviewercamera.h"
#include "llviewertexturelist.h"
#include "llviewerregion.h"
#include "pipeline.h"
#include "llspatialpartition.h"
#include "llworld.h"
#include "lldir.h"
#include "llxmltree.h"
#include "llvotree.h"

const S32 GRASS_MAX_BLADES =    32;
const F32 GRASS_BLADE_BASE =    0.25f;          //  Width of grass at base
const F32 GRASS_BLADE_HEIGHT =  0.5f;           // meters
const F32 GRASS_DISTRIBUTION_SD = 0.15f;        // empirically defined

F32 exp_x[GRASS_MAX_BLADES];
F32 exp_y[GRASS_MAX_BLADES];
F32 rot_x[GRASS_MAX_BLADES];
F32 rot_y[GRASS_MAX_BLADES];
F32 dz_x [GRASS_MAX_BLADES];
F32 dz_y [GRASS_MAX_BLADES];

F32 w_mod[GRASS_MAX_BLADES];                    //  Factor to modulate wind movement by to randomize appearance

LLVOGrass::SpeciesMap LLVOGrass::sSpeciesTable;
S32 LLVOGrass::sMaxGrassSpecies = 0;


LLVOGrass::LLVOGrass(const LLUUID &id, const LLPCode pcode, LLViewerRegion *regionp)
:   LLAlphaObject(id, pcode, regionp)
{
    mPatch               = NULL;
    mLastPatchUpdateTime = 0;
    mGrassVel.clearVec();
    mGrassBend.clearVec();
    mbCanSelect          = true;

    mBladeWindAngle      = 35.f;
    mBWAOverlap          = 2.f;

    setNumTEs(1);

    setTEColor(0, LLColor4(1.0f, 1.0f, 1.0f, 1.f));
    mNumBlades = GRASS_MAX_BLADES;
}

LLVOGrass::~LLVOGrass()
{
}


void LLVOGrass::updateSpecies()
{
    mSpecies = getAttachmentState();

    if (!sSpeciesTable.count(mSpecies))
    {
        LL_INFOS() << "Unknown grass type, substituting grass type." << LL_ENDL;
        SpeciesMap::const_iterator it = sSpeciesTable.begin();
        mSpecies = (*it).first;
    }
    setTEImage(0, LLViewerTextureManager::getFetchedTexture(sSpeciesTable[mSpecies]->mTextureID, FTT_DEFAULT, true, LLGLTexture::BOOST_NONE, LLViewerTexture::LOD_TEXTURE));
}


void LLVOGrass::initClass()
{
    LLVector3 pos(0.0f, 0.0f, 0.0f);
    //  Create nifty list of exponential distribution 0-1
    F32 x = 0.f;
    F32 y = 0.f;
    F32 rot;

    std::string xml_filename = gDirUtilp->getExpandedFilename(LL_PATH_APP_SETTINGS,"grass.xml");

    LLXmlTree grass_def_grass;

    if (!grass_def_grass.parseFile(xml_filename))
    {
        LL_ERRS() << "Failed to parse grass file." << LL_ENDL;
        return;
    }

    LLXmlTreeNode* rootp = grass_def_grass.getRoot();

    for (LLXmlTreeNode* grass_def = rootp->getFirstChild();
        grass_def;
        grass_def = rootp->getNextChild())
    {
        if (!grass_def->hasName("grass"))
        {
            LL_WARNS() << "Invalid grass definition node " << grass_def->getName() << LL_ENDL;
            continue;
        }
        F32 F32_val;
        LLUUID id;

        bool success{ true };

        S32 species;
        static LLStdStringHandle species_id_string = LLXmlTree::addAttributeString("species_id");
        if (!grass_def->getFastAttributeS32(species_id_string, species))
        {
            LL_WARNS() << "No species id defined" << LL_ENDL;
            continue;
        }

        if (species < 0)
        {
            LL_WARNS() << "Invalid species id " << species << LL_ENDL;
            continue;
        }

        GrassSpeciesData* newGrass = new GrassSpeciesData();


        static LLStdStringHandle texture_id_string = LLXmlTree::addAttributeString("texture_id");
        grass_def->getFastAttributeUUID(texture_id_string, id);
        newGrass->mTextureID = id;

        static LLStdStringHandle blade_sizex_string = LLXmlTree::addAttributeString("blade_size_x");
        success &= grass_def->getFastAttributeF32(blade_sizex_string, F32_val);
        newGrass->mBladeSizeX = F32_val;

        static LLStdStringHandle blade_sizey_string = LLXmlTree::addAttributeString("blade_size_y");
        success &= grass_def->getFastAttributeF32(blade_sizey_string, F32_val);
        newGrass->mBladeSizeY = F32_val;

        if (sSpeciesTable.count(species))
        {
            LL_INFOS() << "Grass species " << species << " already defined! Duplicate discarded." << LL_ENDL;
            delete newGrass;
            continue;
        }
        else
        {
            sSpeciesTable[species] = newGrass;
        }

        if (species >= sMaxGrassSpecies) sMaxGrassSpecies = species + 1;

        if (!success)
        {
            std::string name;
            static LLStdStringHandle name_string = LLXmlTree::addAttributeString("name");
            grass_def->getFastAttributeString(name_string, name);
            LL_WARNS() << "Incomplete definition of grass " << name << LL_ENDL;
        }
    }

    bool have_all_grass{ true };
    std::string err;

    for (S32 i=0;i<sMaxGrassSpecies;++i)
    {
        if (!sSpeciesTable.count(i))
        {
            err.append(llformat(" %d",i));
            have_all_grass = false;
        }
    }

    if (!have_all_grass)
    {
        LLSD args;
        args["SPECIES"] = err;
        LLNotificationsUtil::add("ErrorUndefinedGrasses", args);
    }

    for (S32 i = 0; i < GRASS_MAX_BLADES; ++i)
    {
        if (1)   //(i%2 == 0)           Uncomment for X blading
        {
            F32 u = sqrt(-2.0f * log(ll_frand()));
            F32 v = 2.0f * F_PI * ll_frand();

            x = u * sin(v) * GRASS_DISTRIBUTION_SD;
            y = u * cos(v) * GRASS_DISTRIBUTION_SD;

            rot = ll_frand(F_PI);
        }
        else
        {
            rot += (F_PI*0.4f + ll_frand(0.2f*F_PI));
        }

        exp_x[i] = x;
        exp_y[i] = y;
        rot_x[i] = sin(rot);
        rot_y[i] = cos(rot);
        dz_x[i] = ll_frand(GRASS_BLADE_BASE * 0.25f);
        dz_y[i] = ll_frand(GRASS_BLADE_BASE * 0.25f);
        w_mod[i] = 0.5f + ll_frand();                       //  Degree to which blade is moved by wind

    }
}

void LLVOGrass::cleanupClass()
{
    for_each(sSpeciesTable.begin(), sSpeciesTable.end(), DeletePairedPointer());
    sSpeciesTable.clear();
}

U32 LLVOGrass::processUpdateMessage(LLMessageSystem *mesgsys,
                                          void **user_data,
                                          U32 block_num,
                                          const EObjectUpdateType update_type,
                                          LLDataPacker *dp)
{
    // Do base class updates...
    U32 retval = LLViewerObject::processUpdateMessage(mesgsys, user_data, block_num, update_type, dp);

    updateSpecies();

    if (  (getVelocity().lengthSquared() > 0.f)
        ||(getAcceleration().lengthSquared() > 0.f)
        ||(getAngularVelocity().lengthSquared() > 0.f))
    {
        LL_INFOS() << "ACK! Moving grass!" << LL_ENDL;
        setVelocity(LLVector3::zero);
        setAcceleration(LLVector3::zero);
        setAngularVelocity(LLVector3::zero);
    }

    if (mDrawable)
    {
        gPipeline.markRebuild(mDrawable, LLDrawable::REBUILD_VOLUME);
    }

    return retval;
}

bool LLVOGrass::isActive() const
{
    return true;
}

void LLVOGrass::idleUpdate(LLAgent &agent, const F64 &time)
{
    if (mDead || !(gPipeline.hasRenderType(LLPipeline::RENDER_TYPE_GRASS)))
    {
        return;
    }

    if (!mDrawable)
    {
        // So drones work.
        return;
    }
    if (!LLVOTree::isTreeRenderingStopped() && !mNumBlades)//restart grass rendering
    {
        mNumBlades = GRASS_MAX_BLADES;
        gPipeline.markRebuild(mDrawable, LLDrawable::REBUILD_ALL);
        return;
    }
    if (mPatch && (mLastPatchUpdateTime != mPatch->getLastUpdateTime()))
    {
        gPipeline.markRebuild(mDrawable, LLDrawable::REBUILD_VOLUME);
    }

    return;
}


void LLVOGrass::setPixelAreaAndAngle(LLAgent &agent)
{
    // This should be the camera's center, as soon as we move to all region-local.
    LLVector3 relative_position = getPositionAgent() - gAgentCamera.getCameraPositionAgent();
    F32 range = relative_position.length();

    F32 max_scale = getMaxScale();

    mAppAngle = (F32) atan2( max_scale, range) * RAD_TO_DEG;

    // Compute pixels per meter at the given range
    F32 pixels_per_meter = LLViewerCamera::getInstance()->getViewHeightInPixels() / (tan(LLViewerCamera::getInstance()->getView()) * range);

    // Assume grass texture is a 5 meter by 5 meter sprite at the grass object's center
    mPixelArea = (pixels_per_meter) * (pixels_per_meter) * 25.f;
}


// BUG could speed this up by caching the relative_position and range calculations
void LLVOGrass::updateTextures()
{
    if (getTEImage(0))
    {
        if (gPipeline.hasRenderDebugMask(LLPipeline::RENDER_DEBUG_TEXTURE_AREA))
        {
            setDebugText(llformat("%4.0f", (F32) sqrt(mPixelArea)));
        }
        getTEImage(0)->addTextureStats(mPixelArea);
    }
}

bool LLVOGrass::updateLOD()
{
    if (mDrawable->getNumFaces() <= 0)
    {
        return false;
    }

    LLFace* face = mDrawable->getFace(0);

    if(LLVOTree::isTreeRenderingStopped())
    {
        if(mNumBlades)
        {
            mNumBlades = 0 ;
            face->setSize(0, 0);
            gPipeline.markRebuild(mDrawable, LLDrawable::REBUILD_ALL);
        }
        return true ;
    }
    if(!mNumBlades)
    {
        mNumBlades = GRASS_MAX_BLADES;
    }

    F32 tan_angle = 0.f;
    S32 num_blades = 0;

    tan_angle = (mScale.mV[0]*mScale.mV[1])/mDrawable->mDistanceWRTCamera;
    num_blades = llmin(GRASS_MAX_BLADES, lltrunc(tan_angle * 5));
    num_blades = llmax(1, num_blades);
    if (num_blades >= (mNumBlades << 1))
    {
        while (mNumBlades < num_blades)
        {
            mNumBlades <<= 1;
        }
        if (face)
        {
            face->setSize(mNumBlades*8, mNumBlades*12);
        }
        gPipeline.markRebuild(mDrawable, LLDrawable::REBUILD_ALL);
    }
    else if (num_blades <= (mNumBlades >> 1))
    {
        while (mNumBlades > num_blades)
        {
            mNumBlades >>=1;
        }

        if (face)
        {
            face->setSize(mNumBlades*8, mNumBlades*12);
        }
        gPipeline.markRebuild(mDrawable, LLDrawable::REBUILD_ALL);
        return true;
    }

    return false;
}

LLDrawable* LLVOGrass::createDrawable(LLPipeline *pipeline)
{
    pipeline->allocDrawable(this);
    mDrawable->setRenderType(LLPipeline::RENDER_TYPE_GRASS);

    return mDrawable;
}

static LLTrace::BlockTimerStatHandle FTM_UPDATE_GRASS("Update Grass");

bool LLVOGrass::updateGeometry(LLDrawable *drawable)
{
    LL_RECORD_BLOCK_TIME(FTM_UPDATE_GRASS);

    dirtySpatialGroup();

    if(!mNumBlades)//stop rendering grass
    {
        if (mDrawable->getNumFaces() > 0)
        {
            LLFace* facep = mDrawable->getFace(0);
            if(facep)
            {
                facep->setSize(0, 0);
            }
        }
    }
    else
    {
        plantBlades();
    }
    return true;
}

void LLVOGrass::plantBlades()
{
    // It is possible that the species of a grass is not defined
    // This is bad, but not the end of the world.
    if (!sSpeciesTable.count(mSpecies))
    {
        LL_INFOS() << "Unknown grass species " << mSpecies << LL_ENDL;
        return;
    }

    if (mDrawable->getNumFaces() < 1)
    {
        mDrawable->setNumFaces(1, NULL, getTEImage(0));
    }

    LLFace *face = mDrawable->getFace(0);
    if (face)
    {
        face->setTexture(getTEImage(0));
        face->setState(LLFace::GLOBAL);
        face->setSize(mNumBlades * 8, mNumBlades * 12);
        face->setVertexBuffer(NULL);
        face->setTEOffset(0);
        face->mCenterLocal = mPosition + mRegionp->getOriginAgent();
        const LLVector4a* ext = mDrawable->getSpatialExtents();
        face->mExtents[0] = ext[0];
        face->mExtents[1] = ext[1];
    }

    mDepth = (face->mCenterLocal - LLViewerCamera::getInstance()->getOrigin())*LLViewerCamera::getInstance()->getAtAxis();
    mDrawable->setPosition(face->mCenterLocal);
    mDrawable->movePartition();
    LLPipeline::sCompiles++;
}

void LLVOGrass::getGeometry(S32 idx,
                                LLStrider<LLVector4a>& verticesp,
                                LLStrider<LLVector3>& normalsp,
                                LLStrider<LLVector2>& texcoordsp,
                                LLStrider<LLColor4U>& colorsp,
                                LLStrider<LLColor4U>& emissivep,
                                LLStrider<U16>& indicesp)
{
    if(!mNumBlades)//stop rendering grass
    {
        return ;
    }

    mPatch = mRegionp->getLand().resolvePatchRegion(getPositionRegion());
    if (mPatch)
        mLastPatchUpdateTime = mPatch->getLastUpdateTime();

    LLVector3 position;
    // Create random blades of grass with gaussian distribution
    F32 x,y,xf,yf,dzx,dzy;

    LLColor4U color(255,255,255,255);

    LLFace *face = mDrawable->getFace(idx);
    if (!face)
        return;

    F32 width  = sSpeciesTable[mSpecies]->mBladeSizeX;
    F32 height = sSpeciesTable[mSpecies]->mBladeSizeY;

    U32 index_offset = face->getGeomIndex();

    for (S32 i = 0;  i < mNumBlades; i++)
    {
        x   = exp_x[i] * mScale.mV[VX];
        y   = exp_y[i] * mScale.mV[VY];
        xf  = rot_x[i] * GRASS_BLADE_BASE * width * w_mod[i];
        yf  = rot_y[i] * GRASS_BLADE_BASE * width * w_mod[i];
        dzx = dz_x [i];
        dzy = dz_y [i];

        LLVector3 v1,v2,v3;
        F32 blade_height= GRASS_BLADE_HEIGHT * height * w_mod[i];

        *texcoordsp++   = LLVector2(0, 0);
        *texcoordsp++   = LLVector2(0, 0);
        *texcoordsp++   = LLVector2(0, 0.98f);
        *texcoordsp++   = LLVector2(0, 0.98f);
        *texcoordsp++   = LLVector2(1, 0);
        *texcoordsp++   = LLVector2(1, 0);
        *texcoordsp++   = LLVector2(1, 0.98f);
        *texcoordsp++   = LLVector2(1, 0.98f);

        position.mV[0]  = mPosition.mV[VX] + x + xf;
        position.mV[1]  = mPosition.mV[VY] + y + yf;
        position.mV[2]  = mRegionp->getLand().resolveHeightRegion(position);
        v1 = position + mRegionp->getOriginAgent();
        (*verticesp++).load3(v1.mV);
        (*verticesp++).load3(v1.mV);


        position.mV[0] += dzx;
        position.mV[1] += dzy;
        position.mV[2] += blade_height;
        v2 = position + mRegionp->getOriginAgent();
        (*verticesp++).load3(v2.mV);
        (*verticesp++).load3(v2.mV);

        position.mV[0]  = mPosition.mV[VX] + x - xf;
        position.mV[1]  = mPosition.mV[VY] + y - xf;
        position.mV[2]  = mRegionp->getLand().resolveHeightRegion(position);
        v3 = position + mRegionp->getOriginAgent();
        (*verticesp++).load3(v3.mV);
        (*verticesp++).load3(v3.mV);

        LLVector3 normal1 = (v1-v2) % (v2-v3);
        normal1.mV[VZ] = 0.75f;
        normal1.normalize();
        LLVector3 normal2 = -normal1;
        normal2.mV[VZ] = -normal2.mV[VZ];

        position.mV[0] += dzx;
        position.mV[1] += dzy;
        position.mV[2] += blade_height;
        v1 = position + mRegionp->getOriginAgent();
        (*verticesp++).load3(v1.mV);
        (*verticesp++).load3(v1.mV);

        *(normalsp++)   = normal1;
        *(normalsp++)   = normal2;
        *(normalsp++)   = normal1;
        *(normalsp++)   = normal2;

        *(normalsp++)   = normal1;
        *(normalsp++)   = normal2;
        *(normalsp++)   = normal1;
        *(normalsp++)   = normal2;

        *(colorsp++)   = color;
        *(colorsp++)   = color;
        *(colorsp++)   = color;
        *(colorsp++)   = color;
        *(colorsp++)   = color;
        *(colorsp++)   = color;
        *(colorsp++)   = color;
        *(colorsp++)   = color;

        *indicesp++     = index_offset + 0;
        *indicesp++     = index_offset + 2;
        *indicesp++     = index_offset + 4;

        *indicesp++     = index_offset + 2;
        *indicesp++     = index_offset + 6;
        *indicesp++     = index_offset + 4;

        *indicesp++     = index_offset + 1;
        *indicesp++     = index_offset + 5;
        *indicesp++     = index_offset + 3;

        *indicesp++     = index_offset + 3;
        *indicesp++     = index_offset + 5;
        *indicesp++     = index_offset + 7;
        index_offset   += 8;
    }

    LLPipeline::sCompiles++;
}

U32 LLVOGrass::getPartitionType() const
{
    return LLViewerRegion::PARTITION_GRASS;
}

LLGrassPartition::LLGrassPartition(LLViewerRegion* regionp)
: LLSpatialPartition(LLDrawPoolAlpha::VERTEX_DATA_MASK | LLVertexBuffer::MAP_TEXTURE_INDEX, true, regionp)
{
    mDrawableType = LLPipeline::RENDER_TYPE_GRASS;
    mPartitionType = LLViewerRegion::PARTITION_GRASS;
    mLODPeriod = 16;
    mDepthMask = true;
    mSlopRatio = 0.1f;
    mRenderPass = LLRenderPass::PASS_GRASS;
}

void LLGrassPartition::addGeometryCount(LLSpatialGroup* group, U32& vertex_count, U32& index_count)
{
    mFaceList.clear();

    LLViewerCamera* camera = LLViewerCamera::getInstance();
    for (LLSpatialGroup::element_iter i = group->getDataBegin(); i != group->getDataEnd(); ++i)
    {
        LLDrawable* drawablep = (LLDrawable*)(*i)->getDrawable();

        if (!drawablep || drawablep->isDead())
        {
            continue;
        }

        LLAlphaObject* obj = (LLAlphaObject*) drawablep->getVObj().get();
        obj->mDepth = 0.f;

        U32 count = 0;
        for (S32 j = 0; j < drawablep->getNumFaces(); ++j)
        {
            drawablep->updateFaceSize(j);

            LLFace* facep = drawablep->getFace(j);
            if ( !facep || !facep->hasGeometry())
            {
                continue;
            }

            if ((facep->getGeomCount() + vertex_count) <= 65536)
            {
                count++;
                facep->mDistance = (facep->mCenterLocal - camera->getOrigin()) * camera->getAtAxis();
                obj->mDepth += facep->mDistance;

                mFaceList.push_back(facep);
                vertex_count += facep->getGeomCount();
                index_count += facep->getIndicesCount();
                llassert(facep->getIndicesCount() < 65536);
            }
            else
            {
                facep->clearVertexBuffer();
            }
        }

        obj->mDepth /= count;
    }
}

void LLGrassPartition::getGeometry(LLSpatialGroup* group)
{
    LL_PROFILE_ZONE_SCOPED;

    std::sort(mFaceList.begin(), mFaceList.end(), LLFace::CompareDistanceGreater());

    U32 index_count = 0;
    U32 vertex_count = 0;

    group->clearDrawMap();

    LLVertexBuffer* buffer = group->mVertexBuffer;

    LLStrider<U16> indicesp;
    LLStrider<LLVector4a> verticesp;
    LLStrider<LLVector3> normalsp;
    LLStrider<LLVector2> texcoordsp;
    LLStrider<LLColor4U> colorsp;

    buffer->getVertexStrider(verticesp);
    buffer->getNormalStrider(normalsp);
    buffer->getColorStrider(colorsp);
    buffer->getTexCoord0Strider(texcoordsp);
    buffer->getIndexStrider(indicesp);

    LLSpatialGroup::drawmap_elem_t& draw_vec = group->mDrawMap[mRenderPass];

    for (std::vector<LLFace*>::iterator i = mFaceList.begin(); i != mFaceList.end(); ++i)
    {
        LLFace* facep = *i;
        LLAlphaObject* object = (LLAlphaObject*) facep->getViewerObject();
        facep->setGeomIndex(vertex_count);
        facep->setIndicesIndex(index_count);
        facep->setVertexBuffer(buffer);
        facep->setPoolType(LLDrawPool::POOL_ALPHA);

        //dummy parameter (unused by this implementation)
        LLStrider<LLColor4U> emissivep;

        object->getGeometry(facep->getTEOffset(), verticesp, normalsp, texcoordsp, colorsp, emissivep, indicesp);

        vertex_count += facep->getGeomCount();
        index_count += facep->getIndicesCount();

        S32 idx = static_cast<S32>(draw_vec.size()) - 1;

        bool fullbright = facep->isState(LLFace::FULLBRIGHT);

        if (idx >= 0 && draw_vec[idx]->mEnd == facep->getGeomIndex()-1 &&
            draw_vec[idx]->mTexture == facep->getTexture() &&
            (U16) (draw_vec[idx]->mEnd - draw_vec[idx]->mStart + facep->getGeomCount()) <= (U32) gGLManager.mGLMaxVertexRange &&
            //draw_vec[idx]->mCount + facep->getIndicesCount() <= (U32) gGLManager.mGLMaxIndexRange &&
            draw_vec[idx]->mEnd - draw_vec[idx]->mStart + facep->getGeomCount() < 4096 &&
            draw_vec[idx]->mFullbright == fullbright)
        {
            draw_vec[idx]->mCount += facep->getIndicesCount();
            draw_vec[idx]->mEnd += facep->getGeomCount();
        }
        else
        {
            U32 start = facep->getGeomIndex();
            U32 end = start + facep->getGeomCount()-1;
            U32 offset = facep->getIndicesStart();
            U32 count = facep->getIndicesCount();
            LLDrawInfo* info = new LLDrawInfo(start,end,count,offset,facep->getTexture(),
                //facep->getTexture(),
                buffer, object->isSelected(), fullbright);

            draw_vec.push_back(info);
            //for alpha sorting
            facep->setDrawInfo(info);
        }
    }

    buffer->unmapBuffer();
    mFaceList.clear();
}

// virtual
void LLVOGrass::updateDrawable(bool force_damped)
{
    // Force an immediate rebuild on any update
    if (mDrawable.notNull())
    {
        mDrawable->updateXform(true);
        gPipeline.markRebuild(mDrawable, LLDrawable::REBUILD_ALL);
    }
    clearChanged(SHIFTED);
}

// virtual
bool LLVOGrass::lineSegmentIntersect(const LLVector4a& start, const LLVector4a& end, S32 face, bool pick_transparent, bool pick_rigged, bool pick_unselectable, S32 *face_hitp,
                                      LLVector4a* intersection,LLVector2* tex_coord, LLVector4a* normal, LLVector4a* tangent)

{
    bool ret = false;
    if (!mbCanSelect ||
        mDrawable->isDead() ||
        !gPipeline.hasRenderType(mDrawable->getRenderType()))
    {
        return false;
    }

    LLVector4a dir;
    dir.setSub(end, start);

    mPatch = mRegionp->getLand().resolvePatchRegion(getPositionRegion());

    LLVector3 position;
    // Create random blades of grass with gaussian distribution
    F32 x,y,xf,yf,dzx,dzy;

    LLColor4U color(255,255,255,255);

    F32 width  = sSpeciesTable[mSpecies]->mBladeSizeX;
    F32 height = sSpeciesTable[mSpecies]->mBladeSizeY;

    LLVector2 tc[4];
    LLVector3 v[4];
    //LLVector3 n[4];

    F32 closest_t = 1.f;

    for (S32 i = 0;  i < mNumBlades; i++)
    {
        x   = exp_x[i] * mScale.mV[VX];
        y   = exp_y[i] * mScale.mV[VY];
        xf  = rot_x[i] * GRASS_BLADE_BASE * width * w_mod[i];
        yf  = rot_y[i] * GRASS_BLADE_BASE * width * w_mod[i];
        dzx = dz_x [i];
        dzy = dz_y [i];

        LLVector3 v1,v2,v3;
        F32 blade_height= GRASS_BLADE_HEIGHT * height * w_mod[i];

        tc[0]   = LLVector2(0, 0);
        tc[1]   = LLVector2(0, 0.98f);
        tc[2]   = LLVector2(1, 0);
        tc[3]   = LLVector2(1, 0.98f);

        position.mV[0]  = mPosition.mV[VX] + x + xf;
        position.mV[1]  = mPosition.mV[VY] + y + yf;
        position.mV[2]  = mRegionp->getLand().resolveHeightRegion(position);
        v[0]    = v1 = position + mRegionp->getOriginAgent();



        position.mV[0] += dzx;
        position.mV[1] += dzy;
        position.mV[2] += blade_height;
        v[1]    = v2 = position + mRegionp->getOriginAgent();

        position.mV[0]  = mPosition.mV[VX] + x - xf;
        position.mV[1]  = mPosition.mV[VY] + y - xf;
        position.mV[2]  = mRegionp->getLand().resolveHeightRegion(position);
        v[2]    = v3 = position + mRegionp->getOriginAgent();

        LLVector3 normal1 = (v1-v2) % (v2-v3);
        normal1.normalize();

        position.mV[0] += dzx;
        position.mV[1] += dzy;
        position.mV[2] += blade_height;
        v[3]    = v1 = position + mRegionp->getOriginAgent();

        F32 a,b,t;

        bool hit = false;


        U32 idx0 = 0,idx1 = 0,idx2 = 0;

        LLVector4a v0a,v1a,v2a,v3a;

        v0a.load3(v[0].mV);
        v1a.load3(v[1].mV);
        v2a.load3(v[2].mV);
        v3a.load3(v[3].mV);


        if (LLTriangleRayIntersect(v0a, v1a, v2a, start, dir, a, b, t))
        {
            hit = true;
            idx0 = 0; idx1 = 1; idx2 = 2;
        }
        else if (LLTriangleRayIntersect(v1a, v3a, v2a, start, dir, a, b, t))
        {
            hit = true;
            idx0 = 1; idx1 = 3; idx2 = 2;
        }
        else if (LLTriangleRayIntersect(v2a, v1a, v0a, start, dir, a, b, t))
        {
            normal1 = -normal1;
            hit = true;
            idx0 = 2; idx1 = 1; idx2 = 0;
        }
        else if (LLTriangleRayIntersect(v2a, v3a, v1a, start, dir, a, b, t))
        {
            normal1 = -normal1;
            hit = true;
            idx0 = 2; idx1 = 3; idx2 = 1;
        }

        if (hit)
        {
            if (t >= 0.f &&
                t <= 1.f &&
                t < closest_t)
            {

                LLVector2 hit_tc = ((1.f - a - b)  * tc[idx0] +
                                      a              * tc[idx1] +
                                      b              * tc[idx2]);
                if (pick_transparent ||
                    getTEImage(0)->getMask(hit_tc))
                {
                    closest_t = t;
                    if (intersection != NULL)
                    {
                        dir.mul(closest_t);
                        intersection->setAdd(start, dir);
                    }

                    if (tex_coord != NULL)
                    {
                        *tex_coord = hit_tc;
                    }

                    if (normal != NULL)
                    {
                        normal->load3(normal1.mV);
                    }
                    ret = true;
                }
            }
        }
    }

    return ret;
}