// Shave and a Haircut
// (c) 2019 Epic Games
// US Patent 6720962

/**********************************************************************
 *<
	FILE:			shaveVrayVoxelPrim.cpp ( was shaveVrayVoxelPrim.cpp ) -- implementation file  

	DESCRIPTION:	Generic hair voxel primitive

	CREATED BY:		Vladimir Dubovoy <vladimir@3dgears.com>

	HISTORY:		created  02-09-2008 ( as part of 3ds Max + VRay hair shaders)
					merged   30-03-2010

 *>
 **********************************************************************/

#include "assert.h"
#include "shaveVrayVoxelPrim.h"
//#include "shaveVrayPrimsSharedFunctions.h"
#include "shaveVrayShadeable.h"
#include "shaveVrayShadeInstance.h"
#include "shaveVrayShadeData.h"
#include "shaveVrayInstance.h"


shaveVrayVoxelPrim::shaveVrayVoxelPrim(IHairVoxel* vox, 
									 VR::VRayCore *vray,
									 shaveVrayInstance *inst):
	shaveVrayVoxelPrimBase(vox,vray)
{
	_hinst()    = inst;
	_numknots() = eDefNumKnots;
	
	for (int i=0; i < eNumSides; i++) 
	{
		float angle=2.0f*VR::pi()*float(i)/float(eNumSides);
		_uc(i)=cosf(angle);
		_vc(i)=sinf(angle);
	}

	if(voxel())
	{
		const HairType& hair = voxel()->GetHair();
		int   numHairs = hair.GetNumStrands();
		if(numHairs == 0)
		{
			//assume all hairs have the same number of segments
			_numknots() = hair.face_end[0] - hair.face_start[0];
		}
	}
	
	shaveVrayShadeable* sh = new shaveVrayShadeable(this);
	if(vray)
	{
		sh->initBSDFpool(vray);
	}
	_shade() = sh;

	//_shinst() = new shaveVrayShadeInstance<moving>(this);
	_shinst() = (VR::VRayShadeInstance*) new shaveVrayShadeInstance(this);

//	_shdata() = new HairVrShadeData();

	//_shdata() = new shaveVrayShadeData(hinst());
	_shdata() = inst->GetShData();

//	_sfprops() = new VR::SurfaceProperties;

	_tipfade() = false;
}

shaveVrayVoxelPrim::~shaveVrayVoxelPrim()
{
	if(shade())
		delete shade();

	if(shinst())
		delete shinst();

	//if(shdata())
	//	delete shdata();

	//if(sfprops())
	//	delete sfprops();
}

bool shaveVrayVoxelPrim::IsColorConst(int strandidx) const
{
	const HairType& hair = voxel()->GetHair();
	return hair.IsColorConst(strandidx);
}

void shaveVrayVoxelPrim::GetRootColor(int strandidx,VR::Color& c) const
{
	const HairType& hair = voxel()->GetHair();
	return hair.GetRootColor(strandidx,c.r,c.g,c.b);
}

float shaveVrayVoxelPrim::GetOpacity(int strandidx) const
{
	const HairType& hair = voxel()->GetHair();
	return hair.GetStrandOpacity(strandidx);
}

float shaveVrayVoxelPrim::GetAmbDiff(int strandidx) const
{
	const HairType& hair = voxel()->GetHair();
	return hair.GetStrandAmbDiff(strandidx);
}

float shaveVrayVoxelPrim::GetGlossiness(int strandidx) const
{
	const HairType& hair = voxel()->GetHair();
	return hair.GetStrandGlossiness(strandidx);
}

float shaveVrayVoxelPrim::GetSpecLevel(int strandidx) const
{
	const HairType& hair = voxel()->GetHair();
	return hair.GetStrandSpecLevel(strandidx);
}

VR::ShadeVec shaveVrayVoxelPrim::GetUVW(int segmentIdx, int strandidx, float segmentOffset, int channel) const {
#if 0 //vlad|22jan2013 - we still do not have valid data in UVSETS
	const HairUVs& hairUVs=voxel()->GetUVs();

	if (channel<0 || channel>=hairUVs.totalUVSets)
		return VR::Vector(0.0f, 0.0f, 0.0f);

	if (strandidx<0 || strandidx>=hairUVs.totalRoots)
		return VR::Vector(0.0f, 0.0f, 0.0f);

	const VERT &uv=hairUVs.uvRoot[strandidx*hairUVs.totalUVSets+channel];
	return VR::Vector(uv.x, uv.y, uv.z);

#else //grabbing it form defaut set of HAIRTYPE
	
	const HairType& hair = voxel()->GetHair();
	int   numHairs = hair.GetNumStrands();

	if (strandidx >= numHairs || strandidx < 0)
		return VR::ShadeVec(0.0f, 0.0f, 0.0f);

	int start;
	int end;
	hair.GetStrand(strandidx, start, end);

	int numKnots=end-start;
	if (segmentIdx<0 || segmentIdx>=numKnots-1)
		return VR::ShadeVec(0.0f, 0.0f, 0.0f);

	VR::ShadeVec uvw0;
	VR::ShadeVec uvw1;

	int min_i=segmentIdx+start;
	GetUV(hair, min_i+0, uvw0);
	GetUV(hair, min_i+1, uvw1);

	return uvw0+(uvw1-uvw0)*segmentOffset;
	
#endif
}

//not optimized routine
void shaveVrayVoxelPrim::GetInterpColor(int segmentIdx, int strandidx, float segmentOffset, VR::Color& res) const
{
	///////////// test ///////////
	//res = VR::Color(1.0f, 0.0f, 0.0f);
	//return;
	//////////////////////////////

	const HairType& hair = voxel()->GetHair();
	int   numHairs = hair.GetNumStrands();

	if(strandidx >= numHairs || strandidx < 0)
	{
		//red hair will be a signal that something goes wrong
		res = VR::Color(1.0f, 0.0f, 0.0f);
		return;
	}
	int start;
	int end;
	hair.GetStrand(strandidx,start,end);
	int nknots = end - start;

	float t=segmentOffset;

	float T=(float) (segmentIdx);
	float d=(T+t)/(float) nknots;

	hair.GetColor(strandidx,d,res.r,res.g,res.b);
}

//not optimized routine
float shaveVrayVoxelPrim::GetInterpOpacity(int segmentIdx, int strandidx, float segmentOffset) const
{
	///////////// test /////////
	//return 1.0f;
	///////////////////////////

	const HairType& hair = voxel()->GetHair();
	int   numHairs = hair.GetNumStrands();

	if(strandidx >= numHairs || strandidx < 0)
	{
		return 1.0f;
	}
	int start;
	int end;
	hair.GetStrand(strandidx,start,end);
	int nknots = end - start;

	float t=segmentOffset;

	float T=(float) (segmentIdx);
	float d=(T+t)/(float) nknots;

	if(d > 1.0f)
		d = 1.0f;

	if(d < 0.0f)
		d = 0.0f;

	float op = hair.GetStrandOpacity(strandidx);
	return op*(1.0f-d);
}

VR::ShadeVec shaveVrayVoxelPrim::GetHairDir(const VR::ShadeVec &hit, int segmentIdx, int strandidx, float segmentOffset) const
{
	//////////// test ////////////
	//return VR::Vector(0.0f, 0.0f, 1.0f);
	////////////////////////////

	const HairType& hair = voxel()->GetHair();
	int   numHairs = hair.GetNumStrands();

	if(strandidx >= numHairs || strandidx < 0)
	{
		return VR::ShadeVec(0.0f, 0.0f, 1.0f);
	}
	int start;
	int end;
	hair.GetStrand(strandidx,start,end);
	int nknots = end - start;

	VR::ShadeVec knot0;
	VR::ShadeVec knot1;
	int min_i=segmentIdx+start;

	GetVert(hair, min_i, knot0);
	GetVert(hair, min_i+1, knot1);
	VR::ShadeVec sg = knot1 - knot0;

	float t=segmentOffset;
	float T=(float) (segmentIdx);
	float d=(T+t)/(float) nknots;

	float sgLen=sg.length();
	VR::ShadeVec dir1=(sgLen<1e-12f)? VR::ShadeVec(0.0f, 0.0f, 0.0f) : (sg/sg.length()); // The direction of the current segment

	VR::ShadeVec dir0; // The direction of the previous segment
	if (min_i-1-start<0) {
		GetSurfNormal(hair, strandidx, dir0);
		dir0.makeNormalized0();
	} else {
		VR::ShadeVec knotb;
		GetVert(hair, min_i-1, knotb);
		dir0=knot0-knotb;
		dir0.makeNormalized0();
	}

	dir0+=(dir1-dir0)*t;
	dir0.makeNormalized0();
	return dir0;
	//return VR::normalize0(dir0+(dir1-dir0)*t);
}