//-----------------------------------------------------------------------------
// Copyright (c) 2007 dhpoware. All Rights Reserved.
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the "Software"),
// to deal in the Software without restriction, including without limitation
// the rights to use, copy, modify, merge, publish, distribute, sublicense,
// and/or sell copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
// IN THE SOFTWARE.
//-----------------------------------------------------------------------------
//
// The methods normalize() and scale() are based on source code from
// http://www.mvps.org/directx/articles/scalemesh9.htm.
//
// The addVertex() method is based on source code from the Direct3D MeshFromOBJ
// sample found in the DirectX SDK.
//
// The generateTangents() method is based on public source code from
// http://www.terathon.com/code/tangent.php.
//
// The importGeometryFirstPass(), importGeometrySecondPass(), and
// importMaterials() methods are based on source code from Nate Robins' OpenGL
// Tutors programs (http://www.xmission.com/~nate/tutors.html).
//
//-----------------------------------------------------------------------------

#include <algorithm>
#include <cmath>
#include <cstring>
#include <limits>
#include <string>
#include <cstdio>
#include "Engine.h"
#include "OBJModel.h"

namespace Engine {

namespace
{
	bool MeshCompFunc(const OBJModel::Mesh &lhs, const OBJModel::Mesh &rhs)
	{
		return lhs.pMaterial->alpha > rhs.pMaterial->alpha;
	}
}

OBJModel::OBJModel()
{
	m_hasPositions = false;
	m_hasNormals = false;
	m_hasTextureCoords = false;
	m_hasTangents = false;

	m_numberOfVertexCoords = 0;
	m_numberOfTextureCoords = 0;
	m_numberOfNormals = 0;
	m_numberOfTriangles = 0;
	m_numberOfMaterials = 0;
	m_numberOfMeshes = 0;

	m_center[0] = m_center[1] = m_center[2] = 0.0f;
	m_width = m_height = m_length = m_radius = 0.0f;
}

OBJModel::~OBJModel()
{
	destroy();
}

void OBJModel::bounds(float center[3], float &width, float &height,
		float &length, float &radius) const
{
	float xMax = std::numeric_limits<float>::min();
	float yMax = std::numeric_limits<float>::min();
	float zMax = std::numeric_limits<float>::min();

	float xMin = std::numeric_limits<float>::max();
	float yMin = std::numeric_limits<float>::max();
	float zMin = std::numeric_limits<float>::max();

	float x = 0.0f;
	float y = 0.0f;
	float z = 0.0f;

	int numVerts = static_cast<int>(m_vertexBuffer.size());

	for (int i = 0; i < numVerts; ++i)
	{
		x = m_vertexBuffer[i].position[0];
		y = m_vertexBuffer[i].position[1];
		z = m_vertexBuffer[i].position[2];

		if (x < xMin)
			xMin = x;

		if (x > xMax)
			xMax = x;

		if (y < yMin)
			yMin = y;

		if (y > yMax)
			yMax = y;

		if (z < zMin)
			zMin = z;

		if (z > zMax)
			zMax = z;
	}

	center[0] = (xMin + xMax) / 2.0f;
	center[1] = (yMin + yMax) / 2.0f;
	center[2] = (zMin + zMax) / 2.0f;

	width = xMax - xMin;
	height = yMax - yMin;
	length = zMax - zMin;

	radius = std::max(std::max(width, height), length);
}

void OBJModel::destroy()
{
	m_hasPositions = false;
	m_hasTextureCoords = false;
	m_hasNormals = false;
	m_hasTangents = false;

	m_numberOfVertexCoords = 0;
	m_numberOfTextureCoords = 0;
	m_numberOfNormals = 0;
	m_numberOfTriangles = 0;
	m_numberOfMaterials = 0;
	m_numberOfMeshes = 0;

	m_center[0] = m_center[1] = m_center[2] = 0.0f;
	m_width = m_height = m_length = m_radius = 0.0f;

	m_directoryPath.clear();

	m_meshes.clear();
	m_materials.clear();
	m_vertexBuffer.clear();
	m_indexBuffer.clear();
	m_attributeBuffer.clear();

	m_vertexCoords.clear();
	m_textureCoords.clear();
	m_normals.clear();

	m_materialCache.clear();
	m_vertexCache.clear();
}

bool OBJModel::import(const char *pszFilename, bool rebuildNormals)
{
	FILE *pFile = fopen(pszFilename, "r");

	if (!pFile)
		return false;

	// Extract the directory the OBJ file is in from the file name.
	// This directory path will be used to load the OBJ's associated MTL file.

	m_directoryPath.clear();

	boost::filesystem::path full_path (pszFilename);
	m_directoryPath = full_path.parent_path().string();

	LogDebug ("parent path for %s is %s", pszFilename, m_directoryPath.c_str());

	// Import the OBJ file.

	importGeometryFirstPass(pFile);
	rewind(pFile);
	importGeometrySecondPass(pFile);
	fclose(pFile);

	// Perform post import tasks.

	buildMeshes();
	bounds(m_center, m_width, m_height, m_length, m_radius);

	// Build vertex normals if required.

	if (rebuildNormals)
	{
		generateNormals();
	}
	else
	{
		if (!hasNormals())
			generateNormals();
	}

	// Build tangents is required.

	for (int i = 0; i < m_numberOfMaterials; ++i)
	{
		if (!m_materials[i].bumpMapFilename.empty())
		{
			generateTangents();
			break;
		}
	}

	return true;
}

void OBJModel::normalize(float scaleTo, bool center)
{
	float width = 0.0f;
	float height = 0.0f;
	float length = 0.0f;
	float radius = 0.0f;
	float centerPos[3] = {0.0f};

	bounds(centerPos, width, height, length, radius);

	float scalingFactor = scaleTo / radius;
	float offset[3] = {0.0f};

	if (center)
	{
		offset[0] = -centerPos[0];
		offset[1] = -centerPos[1];
		offset[2] = -centerPos[2];
	}
	else
	{
		offset[0] = 0.0f;
		offset[1] = 0.0f;
		offset[2] = 0.0f;
	}

	scale(scalingFactor, offset);
	bounds(m_center, m_width, m_height, m_length, m_radius);
}

void OBJModel::reverseWinding()
{
	int swap = 0;

	// Reverse face winding.
	for (int i = 0; i < static_cast<int>(m_indexBuffer.size()); i += 3)
	{
		swap = m_indexBuffer[i + 1];
		m_indexBuffer[i + 1] = m_indexBuffer[i + 2];
		m_indexBuffer[i + 2] = swap;
	}

	float *pNormal = 0;
	float *pTangent = 0;

	// Invert normals and tangents.
	for (int i = 0; i < static_cast<int>(m_vertexBuffer.size()); ++i)
	{
		pNormal = m_vertexBuffer[i].normal;
		pNormal[0] = -pNormal[0];
		pNormal[1] = -pNormal[1];
		pNormal[2] = -pNormal[2];

		pTangent = m_vertexBuffer[i].tangent;
		pTangent[0] = -pTangent[0];
		pTangent[1] = -pTangent[1];
		pTangent[2] = -pTangent[2];
	}
}

void OBJModel::scale(float scaleFactor, float offset[3])
{
	float *pPosition = 0;

	for (int i = 0; i < static_cast<int>(m_vertexBuffer.size()); ++i)
	{
		pPosition = m_vertexBuffer[i].position;

		pPosition[0] += offset[0];
		pPosition[1] += offset[1];
		pPosition[2] += offset[2];

		pPosition[0] *= scaleFactor;
		pPosition[1] *= scaleFactor;
		pPosition[2] *= scaleFactor;
	}
}

void OBJModel::addTrianglePos(int index, int material, int v0, int v1, int v2)
{
	Vertex vertex =
	{
		{0.0f, 0.0f, 0.0f},
		{0.0f, 0.0f},
		{0.0f, 0.0f, 0.0f}
	};

	m_attributeBuffer[index] = material;

	vertex.position[0] = m_vertexCoords[v0 * 3];
	vertex.position[1] = m_vertexCoords[v0 * 3 + 1];
	vertex.position[2] = m_vertexCoords[v0 * 3 + 2];
	m_indexBuffer[index * 3] = addVertex(v0, &vertex);

	vertex.position[0] = m_vertexCoords[v1 * 3];
	vertex.position[1] = m_vertexCoords[v1 * 3 + 1];
	vertex.position[2] = m_vertexCoords[v1 * 3 + 2];
	m_indexBuffer[index * 3 + 1] = addVertex(v1, &vertex);

	vertex.position[0] = m_vertexCoords[v2 * 3];
	vertex.position[1] = m_vertexCoords[v2 * 3 + 1];
	vertex.position[2] = m_vertexCoords[v2 * 3 + 2];
	m_indexBuffer[index * 3 + 2] = addVertex(v2, &vertex);
}

void OBJModel::addTrianglePosNormal(int index, int material, int v0, int v1,
		int v2, int vn0, int vn1, int vn2)
{
	Vertex vertex =
	{
		{0.0f, 0.0f, 0.0f},
		{0.0f, 0.0f},
		{0.0f, 0.0f, 0.0f},
		{0.0f, 0.0f, 0.0f}
	};

	m_attributeBuffer[index] = material;

	vertex.position[0] = m_vertexCoords[v0 * 3];
	vertex.position[1] = m_vertexCoords[v0 * 3 + 1];
	vertex.position[2] = m_vertexCoords[v0 * 3 + 2];
	vertex.normal[0] = m_normals[vn0 * 3];
	vertex.normal[1] = m_normals[vn0 * 3 + 1];
	vertex.normal[2] = m_normals[vn0 * 3 + 2];
	m_indexBuffer[index * 3] = addVertex(v0, &vertex);

	vertex.position[0] = m_vertexCoords[v1 * 3];
	vertex.position[1] = m_vertexCoords[v1 * 3 + 1];
	vertex.position[2] = m_vertexCoords[v1 * 3 + 2];
	vertex.normal[0] = m_normals[vn1 * 3];
	vertex.normal[1] = m_normals[vn1 * 3 + 1];
	vertex.normal[2] = m_normals[vn1 * 3 + 2];
	m_indexBuffer[index * 3 + 1] = addVertex(v1, &vertex);

	vertex.position[0] = m_vertexCoords[v2 * 3];
	vertex.position[1] = m_vertexCoords[v2 * 3 + 1];
	vertex.position[2] = m_vertexCoords[v2 * 3 + 2];
	vertex.normal[0] = m_normals[vn2 * 3];
	vertex.normal[1] = m_normals[vn2 * 3 + 1];
	vertex.normal[2] = m_normals[vn2 * 3 + 2];
	m_indexBuffer[index * 3 + 2] = addVertex(v2, &vertex);
}

void OBJModel::addTrianglePosTexCoord(int index, int material, int v0, int v1,
		int v2, int vt0, int vt1, int vt2)
{
	Vertex vertex =
	{
		{0.0f, 0.0f, 0.0f},
		{0.0f, 0.0f},
		{0.0f, 0.0f, 0.0f},
		{0.0f, 0.0f, 0.0f}
	};

	m_attributeBuffer[index] = material;

	vertex.position[0] = m_vertexCoords[v0 * 3];
	vertex.position[1] = m_vertexCoords[v0 * 3 + 1];
	vertex.position[2] = m_vertexCoords[v0 * 3 + 2];
	vertex.texCoord[0] = m_textureCoords[vt0 * 2];
	vertex.texCoord[1] = m_textureCoords[vt0 * 2 + 1];
	m_indexBuffer[index * 3] = addVertex(v0, &vertex);

	vertex.position[0] = m_vertexCoords[v1 * 3];
	vertex.position[1] = m_vertexCoords[v1 * 3 + 1];
	vertex.position[2] = m_vertexCoords[v1 * 3 + 2];
	vertex.texCoord[0] = m_textureCoords[vt1 * 2];
	vertex.texCoord[1] = m_textureCoords[vt1 * 2 + 1];
	m_indexBuffer[index * 3 + 1] = addVertex(v1, &vertex);

	vertex.position[0] = m_vertexCoords[v2 * 3];
	vertex.position[1] = m_vertexCoords[v2 * 3 + 1];
	vertex.position[2] = m_vertexCoords[v2 * 3 + 2];
	vertex.texCoord[0] = m_textureCoords[vt2 * 2];
	vertex.texCoord[1] = m_textureCoords[vt2 * 2 + 1];
	m_indexBuffer[index * 3 + 2] = addVertex(v2, &vertex);
}

void OBJModel::addTrianglePosTexCoordNormal(int index, int material, int v0,
		int v1, int v2, int vt0, int vt1,
		int vt2, int vn0, int vn1, int vn2)
{
	Vertex vertex =
	{
		{0.0f, 0.0f, 0.0f},
		{0.0f, 0.0f},
		{0.0f, 0.0f, 0.0f},
		{0.0f, 0.0f, 0.0f}
	};

	m_attributeBuffer[index] = material;

	vertex.position[0] = m_vertexCoords[v0 * 3];
	vertex.position[1] = m_vertexCoords[v0 * 3 + 1];
	vertex.position[2] = m_vertexCoords[v0 * 3 + 2];
	vertex.texCoord[0] = m_textureCoords[vt0 * 2];
	vertex.texCoord[1] = m_textureCoords[vt0 * 2 + 1];
	vertex.normal[0] = m_normals[vn0 * 3];
	vertex.normal[1] = m_normals[vn0 * 3 + 1];
	vertex.normal[2] = m_normals[vn0 * 3 + 2];
	m_indexBuffer[index * 3] = addVertex(v0, &vertex);

	vertex.position[0] = m_vertexCoords[v1 * 3];
	vertex.position[1] = m_vertexCoords[v1 * 3 + 1];
	vertex.position[2] = m_vertexCoords[v1 * 3 + 2];
	vertex.texCoord[0] = m_textureCoords[vt1 * 2];
	vertex.texCoord[1] = m_textureCoords[vt1 * 2 + 1];
	vertex.normal[0] = m_normals[vn1 * 3];
	vertex.normal[1] = m_normals[vn1 * 3 + 1];
	vertex.normal[2] = m_normals[vn1 * 3 + 2];
	m_indexBuffer[index * 3 + 1] = addVertex(v1, &vertex);

	vertex.position[0] = m_vertexCoords[v2 * 3];
	vertex.position[1] = m_vertexCoords[v2 * 3 + 1];
	vertex.position[2] = m_vertexCoords[v2 * 3 + 2];
	vertex.texCoord[0] = m_textureCoords[vt2 * 2];
	vertex.texCoord[1] = m_textureCoords[vt2 * 2 + 1];
	vertex.normal[0] = m_normals[vn2 * 3];
	vertex.normal[1] = m_normals[vn2 * 3 + 1];
	vertex.normal[2] = m_normals[vn2 * 3 + 2];
	m_indexBuffer[index * 3 + 2] = addVertex(v2, &vertex);
}

int OBJModel::addVertex(int hash, const Vertex *pVertex)
{
	int index = -1;
	std::map<int, std::vector<int> >::const_iterator iter = m_vertexCache.find(hash);

	if (iter == m_vertexCache.end())
	{
		// Vertex hash doesn't exist in the cache.

		index = static_cast<int>(m_vertexBuffer.size());
		m_vertexBuffer.push_back(*pVertex);
		m_vertexCache.insert(std::make_pair(hash, std::vector<int>(1, index)));
	}
	else
	{
		// One or more vertices have been hashed to this entry in the cache.

		const std::vector<int> &vertices = iter->second;
		const Vertex *pCachedVertex = 0;
		bool found = false;

		for (std::vector<int>::const_iterator i = vertices.begin(); i != vertices.end(); ++i)
		{
			index = *i;
			pCachedVertex = &m_vertexBuffer[index];

			if (memcmp(pCachedVertex, pVertex, sizeof(Vertex)) == 0)
			{
				found = true;
				break;
			}
		}

		if (!found)
		{
			index = static_cast<int>(m_vertexBuffer.size());
			m_vertexBuffer.push_back(*pVertex);
			m_vertexCache[hash].push_back(index);
		}
	}

	return index;
}

void OBJModel::buildMeshes()
{
	// Group the model's triangles based on material type.

	Mesh *pMesh = 0;
	int materialId = -1;
	int numMeshes = 0;

	// Count the number of meshes.
	for (int i = 0; i < static_cast<int>(m_attributeBuffer.size()); ++i)
	{
		if (m_attributeBuffer[i] != materialId)
		{
			materialId = m_attributeBuffer[i];
			++numMeshes;
		}
	}

	// Allocate memory for the meshes and reset counters.
	m_numberOfMeshes = numMeshes;
	m_meshes.resize(m_numberOfMeshes);
	numMeshes = 0;
	materialId = -1;

	// Build the meshes. One mesh for each unique material.
	for (int i = 0; i < static_cast<int>(m_attributeBuffer.size()); ++i)
	{
		if (m_attributeBuffer[i] != materialId)
		{
			materialId = m_attributeBuffer[i];
			pMesh = &m_meshes[numMeshes++];            
			pMesh->pMaterial = &m_materials[materialId];
			pMesh->startIndex = i * 3;
			++pMesh->triangleCount;
		}
		else
		{
			++pMesh->triangleCount;
		}
	}

	// Sort the meshes based on its material alpha. Fully opaque meshes
	// towards the front and fully transparent towards the back.
	std::sort(m_meshes.begin(), m_meshes.end(), MeshCompFunc);
}

void OBJModel::generateNormals()
{
	const int *pTriangle = 0;
	Vertex *pVertex0 = 0;
	Vertex *pVertex1 = 0;
	Vertex *pVertex2 = 0;
	float edge1[3] = {0.0f, 0.0f, 0.0f};
	float edge2[3] = {0.0f, 0.0f, 0.0f};
	float normal[3] = {0.0f, 0.0f, 0.0f};
	float length = 0.0f;
	int totalVertices = getNumberOfVertices();
	int totalTriangles = getNumberOfTriangles();

	// Initialize all the vertex normals.
	for (int i = 0; i < totalVertices; ++i)
	{
		pVertex0 = &m_vertexBuffer[i];
		pVertex0->normal[0] = 0.0f;
		pVertex0->normal[1] = 0.0f;
		pVertex0->normal[2] = 0.0f;
	}

	// Calculate the vertex normals.
	for (int i = 0; i < totalTriangles; ++i)
	{
		pTriangle = &m_indexBuffer[i * 3];

		pVertex0 = &m_vertexBuffer[pTriangle[0]];
		pVertex1 = &m_vertexBuffer[pTriangle[1]];
		pVertex2 = &m_vertexBuffer[pTriangle[2]];

		// Calculate triangle face normal.

		edge1[0] = pVertex1->position[0] - pVertex0->position[0];
		edge1[1] = pVertex1->position[1] - pVertex0->position[1];
		edge1[2] = pVertex1->position[2] - pVertex0->position[2];

		edge2[0] = pVertex2->position[0] - pVertex0->position[0];
		edge2[1] = pVertex2->position[1] - pVertex0->position[1];
		edge2[2] = pVertex2->position[2] - pVertex0->position[2];

		normal[0] = (edge1[1] * edge2[2]) - (edge1[2] * edge2[1]);
		normal[1] = (edge1[2] * edge2[0]) - (edge1[0] * edge2[2]);
		normal[2] = (edge1[0] * edge2[1]) - (edge1[1] * edge2[0]);

		// Accumulate the normals.

		pVertex0->normal[0] += normal[0];
		pVertex0->normal[1] += normal[1];
		pVertex0->normal[2] += normal[2];

		pVertex1->normal[0] += normal[0];
		pVertex1->normal[1] += normal[1];
		pVertex1->normal[2] += normal[2];

		pVertex2->normal[0] += normal[0];
		pVertex2->normal[1] += normal[1];
		pVertex2->normal[2] += normal[2];
	}

	// Normalize the vertex normals.
	for (int i = 0; i < totalVertices; ++i)
	{
		pVertex0 = &m_vertexBuffer[i];

		length = 1.0f / sqrtf(pVertex0->normal[0] * pVertex0->normal[0] +
				pVertex0->normal[1] * pVertex0->normal[1] +
				pVertex0->normal[2] * pVertex0->normal[2]);

		pVertex0->normal[0] *= length;
		pVertex0->normal[1] *= length;
		pVertex0->normal[2] *= length;
	}

	m_hasNormals = true;
}

void OBJModel::generateTangents()
{
	const int *pTriangle = 0;
	Vertex *pVertex0 = 0;
	Vertex *pVertex1 = 0;
	Vertex *pVertex2 = 0;
	float edge1[3] = {0.0f, 0.0f, 0.0f};
	float edge2[3] = {0.0f, 0.0f, 0.0f};
	float texEdge1[2] = {0.0f, 0.0f};
	float texEdge2[2] = {0.0f, 0.0f};
	float tangent[3] = {0.0f, 0.0f, 0.0f};
	float bitangent[3] = {0.0f, 0.0f, 0.0f};
	float det = 0.0f;
	float nDotT = 0.0f;
	float bDotB = 0.0f;
	float length = 0.0f;
	int totalVertices = getNumberOfVertices();
	int totalTriangles = getNumberOfTriangles();

	// Initialize all the vertex tangents and bitangents.
	for (int i = 0; i < totalVertices; ++i)
	{
		pVertex0 = &m_vertexBuffer[i];

		pVertex0->tangent[0] = 0.0f;
		pVertex0->tangent[1] = 0.0f;
		pVertex0->tangent[2] = 0.0f;
		pVertex0->tangent[3] = 0.0f;

		pVertex0->bitangent[0] = 0.0f;
		pVertex0->bitangent[1] = 0.0f;
		pVertex0->bitangent[2] = 0.0f;
	}

	// Calculate the vertex tangents and bitangents.
	for (int i = 0; i < totalTriangles; ++i)
	{
		pTriangle = &m_indexBuffer[i * 3];

		pVertex0 = &m_vertexBuffer[pTriangle[0]];
		pVertex1 = &m_vertexBuffer[pTriangle[1]];
		pVertex2 = &m_vertexBuffer[pTriangle[2]];

		// Calculate the triangle face tangent and bitangent.

		edge1[0] = pVertex1->position[0] - pVertex0->position[0];
		edge1[1] = pVertex1->position[1] - pVertex0->position[1];
		edge1[2] = pVertex1->position[2] - pVertex0->position[2];

		edge2[0] = pVertex2->position[0] - pVertex0->position[0];
		edge2[1] = pVertex2->position[1] - pVertex0->position[1];
		edge2[2] = pVertex2->position[2] - pVertex0->position[2];

		texEdge1[0] = pVertex1->texCoord[0] - pVertex0->texCoord[0];
		texEdge1[1] = pVertex1->texCoord[1] - pVertex0->texCoord[1];

		texEdge2[0] = pVertex2->texCoord[0] - pVertex0->texCoord[0];
		texEdge2[1] = pVertex2->texCoord[1] - pVertex0->texCoord[1];

		det = texEdge1[0] * texEdge2[1] - texEdge2[0] * texEdge1[1];

		if (fabs(det) < 1e-6f)
		{
			tangent[0] = 1.0f;
			tangent[1] = 0.0f;
			tangent[2] = 0.0f;

			bitangent[0] = 0.0f;
			bitangent[1] = 1.0f;
			bitangent[2] = 0.0f;
		}
		else
		{
			det = 1.0f / det;

			tangent[0] = (texEdge2[1] * edge1[0] - texEdge1[1] * edge2[0]) * det;
			tangent[1] = (texEdge2[1] * edge1[1] - texEdge1[1] * edge2[1]) * det;
			tangent[2] = (texEdge2[1] * edge1[2] - texEdge1[1] * edge2[2]) * det;

			bitangent[0] = (-texEdge2[0] * edge1[0] + texEdge1[0] * edge2[0]) * det;
			bitangent[1] = (-texEdge2[0] * edge1[1] + texEdge1[0] * edge2[1]) * det;
			bitangent[2] = (-texEdge2[0] * edge1[2] + texEdge1[0] * edge2[2]) * det;
		}

		// Accumulate the tangents and bitangents.

		pVertex0->tangent[0] += tangent[0];
		pVertex0->tangent[1] += tangent[1];
		pVertex0->tangent[2] += tangent[2];
		pVertex0->bitangent[0] += bitangent[0];
		pVertex0->bitangent[1] += bitangent[1];
		pVertex0->bitangent[2] += bitangent[2];

		pVertex1->tangent[0] += tangent[0];
		pVertex1->tangent[1] += tangent[1];
		pVertex1->tangent[2] += tangent[2];
		pVertex1->bitangent[0] += bitangent[0];
		pVertex1->bitangent[1] += bitangent[1];
		pVertex1->bitangent[2] += bitangent[2];

		pVertex2->tangent[0] += tangent[0];
		pVertex2->tangent[1] += tangent[1];
		pVertex2->tangent[2] += tangent[2];
		pVertex2->bitangent[0] += bitangent[0];
		pVertex2->bitangent[1] += bitangent[1];
		pVertex2->bitangent[2] += bitangent[2];
	}

	// Orthogonalize and normalize the vertex tangents.
	for (int i = 0; i < totalVertices; ++i)
	{
		pVertex0 = &m_vertexBuffer[i];

		// Gram-Schmidt orthogonalize tangent with normal.

		nDotT = pVertex0->normal[0] * pVertex0->tangent[0] +
			pVertex0->normal[1] * pVertex0->tangent[1] +
			pVertex0->normal[2] * pVertex0->tangent[2];

		pVertex0->tangent[0] -= pVertex0->normal[0] * nDotT;
		pVertex0->tangent[1] -= pVertex0->normal[1] * nDotT;
		pVertex0->tangent[2] -= pVertex0->normal[2] * nDotT;

		// Normalize the tangent.

		length = 1.0f / sqrtf(pVertex0->tangent[0] * pVertex0->tangent[0] +
				pVertex0->tangent[1] * pVertex0->tangent[1] +
				pVertex0->tangent[2] * pVertex0->tangent[2]);

		pVertex0->tangent[0] *= length;
		pVertex0->tangent[1] *= length;
		pVertex0->tangent[2] *= length;

		// Calculate the handedness of the local tangent space.
		// The bitangent vector is the cross product between the triangle face
		// normal vector and the calculated tangent vector. The resulting
		// bitangent vector should be the same as the bitangent vector
		// calculated from the set of linear equations above. If they point in
		// different directions then we need to invert the cross product
		// calculated bitangent vector. We store this scalar multiplier in the
		// tangent vector's 'w' component so that the correct bitangent vector
		// can be generated in the normal mapping shader's vertex shader.
		//
		// Normal maps have a left handed coordinate system with the origin
		// located at the top left of the normal map texture. The x coordinates
		// run horizontally from left to right. The y coordinates run
		// vertically from top to bottom. The z coordinates run out of the
		// normal map texture towards the viewer. Our handedness calculations
		// must take this fact into account as well so that the normal mapping
		// shader's vertex shader will generate the correct bitangent vectors.
		// Some normal map authoring tools such as Crazybump
		// (http://www.crazybump.com/) includes options to allow you to control
		// the orientation of the normal map normal's y-axis.

		bitangent[0] = (pVertex0->normal[1] * pVertex0->tangent[2]) - 
			(pVertex0->normal[2] * pVertex0->tangent[1]);
		bitangent[1] = (pVertex0->normal[2] * pVertex0->tangent[0]) -
			(pVertex0->normal[0] * pVertex0->tangent[2]);
		bitangent[2] = (pVertex0->normal[0] * pVertex0->tangent[1]) - 
			(pVertex0->normal[1] * pVertex0->tangent[0]);

		bDotB = bitangent[0] * pVertex0->bitangent[0] + 
			bitangent[1] * pVertex0->bitangent[1] + 
			bitangent[2] * pVertex0->bitangent[2];

		pVertex0->tangent[3] = (bDotB < 0.0f) ? 1.0f : -1.0f;

		pVertex0->bitangent[0] = bitangent[0];
		pVertex0->bitangent[1] = bitangent[1];
		pVertex0->bitangent[2] = bitangent[2];
	}

	m_hasTangents = true;
}

void OBJModel::importGeometryFirstPass(FILE *pFile)
{
	m_hasTextureCoords = false;
	m_hasNormals = false;

	m_numberOfVertexCoords = 0;
	m_numberOfTextureCoords = 0;
	m_numberOfNormals = 0;
	m_numberOfTriangles = 0;

	int v = 0;
	int vt = 0;
	int vn = 0;
	char buffer[256] = {0};
	std::string name;

	boost::filesystem::path file_path;

	while (fscanf(pFile, "%s", buffer) != EOF)
	{
		switch (buffer[0])
		{
			case 'f':   // v, v//vn, v/vt, v/vt/vn.
				fscanf(pFile, "%s", buffer);

				if (strstr(buffer, "//")) // v//vn
				{
					sscanf(buffer, "%d//%d", &v, &vn);
					fscanf(pFile, "%d//%d", &v, &vn);
					fscanf(pFile, "%d//%d", &v, &vn);
					++m_numberOfTriangles;

					while (fscanf(pFile, "%d//%d", &v, &vn) > 0)
						++m_numberOfTriangles;
				}
				else if (sscanf(buffer, "%d/%d/%d", &v, &vt, &vn) == 3) // v/vt/vn
				{
					fscanf(pFile, "%d/%d/%d", &v, &vt, &vn);
					fscanf(pFile, "%d/%d/%d", &v, &vt, &vn);
					++m_numberOfTriangles;

					while (fscanf(pFile, "%d/%d/%d", &v, &vt, &vn) > 0)
						++m_numberOfTriangles;
				}
				else if (sscanf(buffer, "%d/%d", &v, &vt) == 2) // v/vt
				{
					fscanf(pFile, "%d/%d", &v, &vt);
					fscanf(pFile, "%d/%d", &v, &vt);
					++m_numberOfTriangles;

					while (fscanf(pFile, "%d/%d", &v, &vt) > 0)
						++m_numberOfTriangles;
				}
				else // v
				{
					fscanf(pFile, "%d", &v);
					fscanf(pFile, "%d", &v);
					++m_numberOfTriangles;

					while (fscanf(pFile, "%d", &v) > 0)
						++m_numberOfTriangles;
				}
				break;

			case 'm':   // mtllib
				fgets(buffer, sizeof(buffer), pFile);
				sscanf(buffer, "%s %s", buffer, buffer);
				file_path = m_directoryPath;
				file_path /= buffer;
//				LogMessage ("full mtl path = %s", file_path.string().c_str());
				name = file_path.string();
				importMaterials(name.c_str());
				break;

			case 'v':   // v, vt, or vn
				switch (buffer[1])
				{
					case '\0':
						fgets(buffer, sizeof(buffer), pFile);
						++m_numberOfVertexCoords;
						break;

					case 'n':
						fgets(buffer, sizeof(buffer), pFile);
						++m_numberOfNormals;
						break;

					case 't':
						fgets(buffer, sizeof(buffer), pFile);
						++m_numberOfTextureCoords;

					default:
						break;
				}
				break;

			default:
				fgets(buffer, sizeof(buffer), pFile);
				break;
		}
	}

	m_hasPositions = m_numberOfVertexCoords > 0;
	m_hasNormals = m_numberOfNormals > 0;
	m_hasTextureCoords = m_numberOfTextureCoords > 0;

	// Allocate memory for the OBJ model data.
	m_vertexCoords.resize(m_numberOfVertexCoords * 3);
	m_textureCoords.resize(m_numberOfTextureCoords * 2);
	m_normals.resize(m_numberOfNormals * 3);
	m_indexBuffer.resize(m_numberOfTriangles * 3);
	m_attributeBuffer.resize(m_numberOfTriangles);

	// Define a default material if no materials were loaded.
	if (m_numberOfMaterials == 0)
	{
		Material defaultMaterial =
		{
			{0.2f, 0.2f, 0.2f, 1.0f},
			{0.8f, 0.8f, 0.8f, 1.0f},
			{0.0f, 0.0f, 0.0f, 1.0f},
			0.0f,
			1.0f,
			std::string("default"),
			std::string(),
			std::string()
		};

		m_materials.push_back(defaultMaterial);
		m_materialCache[defaultMaterial.name] = 0;
	}
}

void OBJModel::importGeometrySecondPass(FILE *pFile)
{
	int v[3] = {0};
	int vt[3] = {0};
	int vn[3] = {0};
	int numVertices = 0;
	int numTexCoords = 0;
	int numNormals = 0;
	int numTriangles = 0;
	int activeMaterial = 0;
	char buffer[256] = {0};
	std::string name;
	std::map<std::string, int>::const_iterator iter;

	while (fscanf(pFile, "%s", buffer) != EOF)
	{
		switch (buffer[0])
		{
			case 'f': // v, v//vn, v/vt, or v/vt/vn.
				v[0]  = v[1]  = v[2]  = 0;
				vt[0] = vt[1] = vt[2] = 0;
				vn[0] = vn[1] = vn[2] = 0;

				fscanf(pFile, "%s", buffer);

				if (strstr(buffer, "//")) // v//vn
				{
					sscanf(buffer, "%d//%d", &v[0], &vn[0]);
					fscanf(pFile, "%d//%d", &v[1], &vn[1]);
					fscanf(pFile, "%d//%d", &v[2], &vn[2]);

					v[0] = (v[0] < 0) ? v[0] + numVertices - 1 : v[0] - 1;
					v[1] = (v[1] < 0) ? v[1] + numVertices - 1 : v[1] - 1;
					v[2] = (v[2] < 0) ? v[2] + numVertices - 1 : v[2] - 1;

					vn[0] = (vn[0] < 0) ? vn[0] + numNormals - 1 : vn[0] - 1;
					vn[1] = (vn[1] < 0) ? vn[1] + numNormals - 1 : vn[1] - 1;
					vn[2] = (vn[2] < 0) ? vn[2] + numNormals - 1 : vn[2] - 1;

					addTrianglePosNormal(numTriangles++, activeMaterial,
							v[0], v[1], v[2], vn[0], vn[1], vn[2]);

					v[1] = v[2];
					vn[1] = vn[2];

					while (fscanf(pFile, "%d//%d", &v[2], &vn[2]) > 0)
					{
						v[2] = (v[2] < 0) ? v[2] + numVertices - 1 : v[2] - 1;
						vn[2] = (vn[2] < 0) ? vn[2] + numNormals - 1 : vn[2] - 1;

						addTrianglePosNormal(numTriangles++, activeMaterial,
								v[0], v[1], v[2], vn[0], vn[1], vn[2]);

						v[1] = v[2];
						vn[1] = vn[2];
					}
				}
				else if (sscanf(buffer, "%d/%d/%d", &v[0], &vt[0], &vn[0]) == 3) // v/vt/vn
				{
					fscanf(pFile, "%d/%d/%d", &v[1], &vt[1], &vn[1]);
					fscanf(pFile, "%d/%d/%d", &v[2], &vt[2], &vn[2]);

					v[0] = (v[0] < 0) ? v[0] + numVertices - 1 : v[0] - 1;
					v[1] = (v[1] < 0) ? v[1] + numVertices - 1 : v[1] - 1;
					v[2] = (v[2] < 0) ? v[2] + numVertices - 1 : v[2] - 1;

					vt[0] = (vt[0] < 0) ? vt[0] + numTexCoords - 1 : vt[0] - 1;
					vt[1] = (vt[1] < 0) ? vt[1] + numTexCoords - 1 : vt[1] - 1;
					vt[2] = (vt[2] < 0) ? vt[2] + numTexCoords - 1 : vt[2] - 1;

					vn[0] = (vn[0] < 0) ? vn[0] + numNormals - 1 : vn[0] - 1;
					vn[1] = (vn[1] < 0) ? vn[1] + numNormals - 1 : vn[1] - 1;
					vn[2] = (vn[2] < 0) ? vn[2] + numNormals - 1 : vn[2] - 1;

					addTrianglePosTexCoordNormal(numTriangles++, activeMaterial,
							v[0], v[1], v[2], vt[0], vt[1], vt[2], vn[0], vn[1], vn[2]);

					v[1] = v[2];
					vt[1] = vt[2];
					vn[1] = vn[2];

					while (fscanf(pFile, "%d/%d/%d", &v[2], &vt[2], &vn[2]) > 0)
					{
						v[2] = (v[2] < 0) ? v[2] + numVertices - 1 : v[2] - 1;
						vt[2] = (vt[2] < 0) ? vt[2] + numTexCoords - 1 : vt[2] - 1;
						vn[2] = (vn[2] < 0) ? vn[2] + numNormals - 1 : vn[2] - 1;

						addTrianglePosTexCoordNormal(numTriangles++, activeMaterial,
								v[0], v[1], v[2], vt[0], vt[1], vt[2], vn[0], vn[1], vn[2]);

						v[1] = v[2];
						vt[1] = vt[2];
						vn[1] = vn[2];
					}
				}
				else if (sscanf(buffer, "%d/%d", &v[0], &vt[0]) == 2) // v/vt
				{
					fscanf(pFile, "%d/%d", &v[1], &vt[1]);
					fscanf(pFile, "%d/%d", &v[2], &vt[2]);

					v[0] = (v[0] < 0) ? v[0] + numVertices - 1 : v[0] - 1;
					v[1] = (v[1] < 0) ? v[1] + numVertices - 1 : v[1] - 1;
					v[2] = (v[2] < 0) ? v[2] + numVertices - 1 : v[2] - 1;

					vt[0] = (vt[0] < 0) ? vt[0] + numTexCoords - 1 : vt[0] - 1;
					vt[1] = (vt[1] < 0) ? vt[1] + numTexCoords - 1 : vt[1] - 1;
					vt[2] = (vt[2] < 0) ? vt[2] + numTexCoords - 1 : vt[2] - 1;

					addTrianglePosTexCoord(numTriangles++, activeMaterial,
							v[0], v[1], v[2], vt[0], vt[1], vt[2]);

					v[1] = v[2];
					vt[1] = vt[2];

					while (fscanf(pFile, "%d/%d", &v[2], &vt[2]) > 0)
					{
						v[2] = (v[2] < 0) ? v[2] + numVertices - 1 : v[2] - 1;
						vt[2] = (vt[2] < 0) ? vt[2] + numTexCoords - 1 : vt[2] - 1;

						addTrianglePosTexCoord(numTriangles++, activeMaterial,
								v[0], v[1], v[2], vt[0], vt[1], vt[2]);

						v[1] = v[2];
						vt[1] = vt[2];
					}
				}
				else // v
				{
					sscanf(buffer, "%d", &v[0]);
					fscanf(pFile, "%d", &v[1]);
					fscanf(pFile, "%d", &v[2]);

					v[0] = (v[0] < 0) ? v[0] + numVertices - 1 : v[0] - 1;
					v[1] = (v[1] < 0) ? v[1] + numVertices - 1 : v[1] - 1;
					v[2] = (v[2] < 0) ? v[2] + numVertices - 1 : v[2] - 1;

					addTrianglePos(numTriangles++, activeMaterial, v[0], v[1], v[2]);

					v[1] = v[2];

					while (fscanf(pFile, "%d", &v[2]) > 0)
					{
						v[2] = (v[2] < 0) ? v[2] + numVertices - 1 : v[2] - 1;

						addTrianglePos(numTriangles++, activeMaterial, v[0], v[1], v[2]);

						v[1] = v[2];
					}
				}
				break;

			case 'u': // usemtl
				fgets(buffer, sizeof(buffer), pFile);
				sscanf(buffer, "%s %s", buffer, buffer);
				name = buffer;
				iter = m_materialCache.find(buffer);
				activeMaterial = (iter == m_materialCache.end()) ? 0 : iter->second;
				break;

			case 'v': // v, vn, or vt.
				switch (buffer[1])
				{
					case '\0': // v
						fscanf(pFile, "%f %f %f",
								&m_vertexCoords[3 * numVertices],
								&m_vertexCoords[3 * numVertices + 1],
								&m_vertexCoords[3 * numVertices + 2]);
						++numVertices;
						break;

					case 'n': // vn
						fscanf(pFile, "%f %f %f",
								&m_normals[3 * numNormals],
								&m_normals[3 * numNormals + 1],
								&m_normals[3 * numNormals + 2]);
						++numNormals;
						break;

					case 't': // vt
						fscanf(pFile, "%f %f",
								&m_textureCoords[2 * numTexCoords],
								&m_textureCoords[2 * numTexCoords + 1]);
						++numTexCoords;
						break;

					default:
						break;
				}
				break;

			default:
				fgets(buffer, sizeof(buffer), pFile);
				break;
		}
	}
}

bool OBJModel::importMaterials(const char *pszFilename)
{
	LogMessage ("Loading material %s", pszFilename);
	FILE *pFile = fopen(pszFilename, "r");

	if (!pFile)
		return false;

	Material *pMaterial = 0;
	int illum = 0;
	int numMaterials = 0;
	char buffer[256] = {0};

	// Count the number of materials in the MTL file.
	while (fscanf(pFile, "%s", buffer) != EOF)
	{
		switch (buffer[0])
		{
			case 'n': // newmtl
				++numMaterials;
				fgets(buffer, sizeof(buffer), pFile);
				sscanf(buffer, "%s %s", buffer, buffer);
				break;

			default:
				fgets(buffer, sizeof(buffer), pFile);
				break;
		}
	}

	rewind(pFile);

	m_numberOfMaterials = numMaterials;

	LogMessage ("file contains %d materials", m_numberOfMaterials);

	numMaterials = 0;
	m_materials.resize(m_numberOfMaterials);
	boost::filesystem::path file_path;

	// Load the materials in the MTL file.
	while (fscanf(pFile, "%s", buffer) != EOF)
	{
		switch (buffer[0])
		{
			case 'N': // Ns
				fscanf(pFile, "%f", &pMaterial->shininess);

				// Wavefront .MTL file shininess is from [0,1000].
				// Scale back to a generic [0,1] range.
				pMaterial->shininess /= 1000.0f;
				break;

			case 'K': // Ka, Kd, or Ks
				switch (buffer[1])
				{
					case 'a': // Ka
						fscanf(pFile, "%f %f %f",
								&pMaterial->ambient[0],
								&pMaterial->ambient[1],
								&pMaterial->ambient[2]);
						pMaterial->ambient[3] = 1.0f;
						break;

					case 'd': // Kd
						fscanf(pFile, "%f %f %f",
								&pMaterial->diffuse[0],
								&pMaterial->diffuse[1],
								&pMaterial->diffuse[2]);
						pMaterial->diffuse[3] = 1.0f;
						break;

					case 's': // Ks
						fscanf(pFile, "%f %f %f",
								&pMaterial->specular[0],
								&pMaterial->specular[1],
								&pMaterial->specular[2]);
						pMaterial->specular[3] = 1.0f;
						break;

					default:
						fgets(buffer, sizeof(buffer), pFile);
						break;
				}
				break;

			case 'T': // Tr
				switch (buffer[1])
				{
					case 'r': // Tr
						fscanf(pFile, "%f", &pMaterial->alpha);
						pMaterial->alpha = 1.0f - pMaterial->alpha;
						break;

					default:
						fgets(buffer, sizeof(buffer), pFile);
						break;
				}
				break;

			case 'd':
				fscanf(pFile, "%f", &pMaterial->alpha);
				break;

			case 'i': // illum
				fscanf(pFile, "%d", &illum);

				if (illum == 1)
				{
					pMaterial->specular[0] = 0.0f;
					pMaterial->specular[1] = 0.0f;
					pMaterial->specular[2] = 0.0f;
					pMaterial->specular[3] = 1.0f;
				}
				break;

			case 'm': // map_Kd, map_bump
				if (strstr(buffer, "map_Kd") != 0)
				{
					fgets(buffer, sizeof(buffer), pFile);
					sscanf(buffer, "%s %s", buffer, buffer);
					file_path = m_directoryPath;
					file_path /= buffer;
					pMaterial->colorMapFilename = file_path.string();
					LogMessage ("colorMapFilename = %s", pMaterial->colorMapFilename.c_str());
				}
				else if (strstr(buffer, "map_bump") != 0)
				{
					fgets(buffer, sizeof(buffer), pFile);
					sscanf(buffer, "%s %s", buffer, buffer);
					file_path = m_directoryPath;
					file_path /= buffer;
					pMaterial->bumpMapFilename = file_path.string();
					LogMessage ("bumpMapFilename = %s", pMaterial->bumpMapFilename.c_str());
				}
				else
				{
					fgets(buffer, sizeof(buffer), pFile);
				}
				break;

			case 'n': // newmtl
				fgets(buffer, sizeof(buffer), pFile);
				sscanf(buffer, "%s %s", buffer, buffer);

				pMaterial = &m_materials[numMaterials];
				pMaterial->ambient[0] = 0.2f;
				pMaterial->ambient[1] = 0.2f;
				pMaterial->ambient[2] = 0.2f;
				pMaterial->ambient[3] = 1.0f;
				pMaterial->diffuse[0] = 0.8f;
				pMaterial->diffuse[1] = 0.8f;
				pMaterial->diffuse[2] = 0.8f;
				pMaterial->diffuse[3] = 1.0f;
				pMaterial->specular[0] = 0.0f;
				pMaterial->specular[1] = 0.0f;
				pMaterial->specular[2] = 0.0f;
				pMaterial->specular[3] = 1.0f;
				pMaterial->shininess = 0.0f;
				pMaterial->alpha = 1.0f;
				pMaterial->name = buffer;
				pMaterial->colorMapFilename.clear();
				pMaterial->bumpMapFilename.clear();

				m_materialCache[pMaterial->name] = numMaterials;
				++numMaterials;
				break;

			default:
				fgets(buffer, sizeof(buffer), pFile);
				break;
		}
	}

	fclose(pFile);
	return true;
}

}