/** 
 * @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;
		std::string name;

		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;

		static LLStdStringHandle name_string = LLXmlTree::addAttributeString("name");
		grass_def->getFastAttributeString(name_string, name);
		newGrass->mName = name;

		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)
		{
			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
	auto& viewerCamera = LLViewerCamera::instance();
	F32 pixels_per_meter = viewerCamera.getViewHeightInPixels() / (tan(viewerCamera.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;
}

BOOL LLVOGrass::updateGeometry(LLDrawable *drawable)
{
	LL_PROFILE_ZONE_NAMED_CATEGORY_DRAWABLE("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();
	}

	auto& viewerCamera = LLViewerCamera::instance();
	mDepth = (face->mCenterLocal - viewerCamera.getOrigin())* viewerCamera.getAtAxis();
	mDrawable->setPosition(face->mCenterLocal);
	mDrawable->movePartition();
}

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;
	}
}

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_end = group->getDataEnd(); i != i_end; ++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 = 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;
}

