////////////////////////////////////////////////////////////////////////////////
// Filename: modelclass.cpp
////////////////////////////////////////////////////////////////////////////////
#include "modelclass.h"


ModelClass::ModelClass()
{
	m_vertexBuffer = 0;
	m_indexBuffer = 0;
	m_Textures = 0;
	m_model = 0;
}


ModelClass::ModelClass(const ModelClass& other)
{
}


ModelClass::~ModelClass()
{
}


bool ModelClass::Initialize(ID3D11Device* device, ID3D11DeviceContext* deviceContext, char* modelFilename, char* textureFilename1, char* textureFilename2, char* textureFilename3)
{
	bool result;


	// Load in the model data.
	result = LoadModel(modelFilename);
	if(!result)
	{
		return false;
	}

	// Calculate the tangent and binormal vectors for the model.
	CalculateModelVectors();

	// Initialize the vertex and index buffers.
	result = InitializeBuffers(device);
	if(!result)
	{
		return false;
	}

	// Load the textures for this model.
	result = LoadTextures(device, deviceContext, textureFilename1, textureFilename2, textureFilename3);
	if(!result)
	{
		return false;
	}

	return true;
}


void ModelClass::Shutdown()
{
	// Release the model textures.
	ReleaseTextures();

	// Shutdown the vertex and index buffers.
	ShutdownBuffers();

	// Release the model data.
	ReleaseModel();

	return;
}


void ModelClass::Render(ID3D11DeviceContext* deviceContext)
{
	// Put the vertex and index buffers on the graphics pipeline to prepare them for drawing.
	RenderBuffers(deviceContext);

	return;
}


int ModelClass::GetIndexCount()
{
	return m_indexCount;
}


ID3D11ShaderResourceView* ModelClass::GetTexture(int index)
{
	return m_Textures[index].GetTexture();
}


bool ModelClass::InitializeBuffers(ID3D11Device* device)
{
	VertexType* vertices;
	unsigned long* indices;
	D3D11_BUFFER_DESC vertexBufferDesc, indexBufferDesc;
    D3D11_SUBRESOURCE_DATA vertexData, indexData;
	HRESULT result;
	int i;


	// Create the vertex array.
	vertices = new VertexType[m_vertexCount];

	// Create the index array.
	indices = new unsigned long[m_indexCount];

	// Load the vertex array and index array with data.
	for(i=0; i<m_vertexCount; i++)
	{
		vertices[i].position = XMFLOAT3(m_model[i].x, m_model[i].y, m_model[i].z);
		vertices[i].texture = XMFLOAT2(m_model[i].tu, m_model[i].tv);
		vertices[i].normal = XMFLOAT3(m_model[i].nx, m_model[i].ny, m_model[i].nz);
		vertices[i].tangent = XMFLOAT3(m_model[i].tx, m_model[i].ty, m_model[i].tz);
		vertices[i].binormal = XMFLOAT3(m_model[i].bx, m_model[i].by, m_model[i].bz);

		indices[i] = i;
	}

	// Set up the description of the static vertex buffer.
    vertexBufferDesc.Usage = D3D11_USAGE_DEFAULT;
    vertexBufferDesc.ByteWidth = sizeof(VertexType) * m_vertexCount;
    vertexBufferDesc.BindFlags = D3D11_BIND_VERTEX_BUFFER;
    vertexBufferDesc.CPUAccessFlags = 0;
    vertexBufferDesc.MiscFlags = 0;
	vertexBufferDesc.StructureByteStride = 0;

	// Give the subresource structure a pointer to the vertex data.
    vertexData.pSysMem = vertices;
	vertexData.SysMemPitch = 0;
	vertexData.SysMemSlicePitch = 0;

	// Now create the vertex buffer.
    result = device->CreateBuffer(&vertexBufferDesc, &vertexData, &m_vertexBuffer);
	if(FAILED(result))
	{
		return false;
	}

	// Set up the description of the static index buffer.
    indexBufferDesc.Usage = D3D11_USAGE_DEFAULT;
    indexBufferDesc.ByteWidth = sizeof(unsigned long) * m_indexCount;
    indexBufferDesc.BindFlags = D3D11_BIND_INDEX_BUFFER;
    indexBufferDesc.CPUAccessFlags = 0;
    indexBufferDesc.MiscFlags = 0;
	indexBufferDesc.StructureByteStride = 0;

	// Give the subresource structure a pointer to the index data.
    indexData.pSysMem = indices;
	indexData.SysMemPitch = 0;
	indexData.SysMemSlicePitch = 0;

	// Create the index buffer.
	result = device->CreateBuffer(&indexBufferDesc, &indexData, &m_indexBuffer);
	if(FAILED(result))
	{
		return false;
	}

	// Release the arrays now that the vertex and index buffers have been created and loaded.
	delete [] vertices;
	vertices = 0;

	delete [] indices;
	indices = 0;

	return true;
}


void ModelClass::ShutdownBuffers()
{
	// Release the index buffer.
	if(m_indexBuffer)
	{
		m_indexBuffer->Release();
		m_indexBuffer = 0;
	}

	// Release the vertex buffer.
	if(m_vertexBuffer)
	{
		m_vertexBuffer->Release();
		m_vertexBuffer = 0;
	}

	return;
}


void ModelClass::RenderBuffers(ID3D11DeviceContext* deviceContext)
{
	unsigned int stride;
	unsigned int offset;


	// Set vertex buffer stride and offset.
	stride = sizeof(VertexType); 
	offset = 0;
    
	// Set the vertex buffer to active in the input assembler so it can be rendered.
	deviceContext->IASetVertexBuffers(0, 1, &m_vertexBuffer, &stride, &offset);

    // Set the index buffer to active in the input assembler so it can be rendered.
	deviceContext->IASetIndexBuffer(m_indexBuffer, DXGI_FORMAT_R32_UINT, 0);

    // Set the type of primitive that should be rendered from this vertex buffer, in this case triangles.
	deviceContext->IASetPrimitiveTopology(D3D11_PRIMITIVE_TOPOLOGY_TRIANGLELIST);

	return;
}


bool ModelClass::LoadTextures(ID3D11Device* device, ID3D11DeviceContext* deviceContext, char* filename1, char* filename2, char* filename3)
{
	bool result;


	// Create and initialize the texture object array.
	m_Textures = new TextureClass[3];

	result = m_Textures[0].Initialize(device, deviceContext, filename1);
	if(!result)
	{
		return false;
	}

	result = m_Textures[1].Initialize(device, deviceContext, filename2);
	if(!result)
	{
		return false;
	}

	result = m_Textures[2].Initialize(device, deviceContext, filename3);
	if(!result)
	{
		return false;
	}

	return true;
}


void ModelClass::ReleaseTextures()
{
	// Release the texture object array.
	if(m_Textures)
	{
		m_Textures[0].Shutdown();
		m_Textures[1].Shutdown();
		m_Textures[2].Shutdown();

		delete [] m_Textures;
		m_Textures = 0;
	}

	return;
}


bool ModelClass::LoadModel(char* filename)
{
	ifstream fin;
	char input;
	int i;


	// Open the model file.
	fin.open(filename);

	// If it could not open the file then exit.
	if(fin.fail())
	{
		return false;
	}

	// Read up to the value of vertex count.
	fin.get(input);
	while (input != ':')
	{
		fin.get(input);
	}

	// Read in the vertex count.
	fin >> m_vertexCount;

	// Set the number of indices to be the same as the vertex count.
	m_indexCount = m_vertexCount;

	// Create the model using the vertex count that was read in.
	m_model = new ModelType[m_vertexCount];

	// Read up to the beginning of the data.
	fin.get(input);
	while (input != ':')
	{
		fin.get(input);
	}
	fin.get(input);
	fin.get(input);

	// Read in the vertex data.
	for(i=0; i<m_vertexCount; i++)
	{
		fin >> m_model[i].x >> m_model[i].y >> m_model[i].z;
		fin >> m_model[i].tu >> m_model[i].tv;
		fin >> m_model[i].nx >> m_model[i].ny >> m_model[i].nz;
	}

	// Close the model file.
	fin.close();

	return true;
}


void ModelClass::ReleaseModel()
{
	if(m_model)
	{
		delete [] m_model;
		m_model = 0;
	}

	return;
}


void ModelClass::CalculateModelVectors()
{
    int faceCount, i, index;
    TempVertexType vertex1, vertex2, vertex3;
    VectorType tangent, binormal;


    // Calculate the number of faces in the model.
    faceCount = m_vertexCount / 3;

    // Initialize the index to the model data.
    index = 0;

    // Go through all the faces and calculate the the tangent and binormal vectors.
    for(i=0; i<faceCount; i++)
    {
        // Get the three vertices for this face from the model.
        vertex1.x = m_model[index].x;
        vertex1.y = m_model[index].y;
        vertex1.z = m_model[index].z;
        vertex1.tu = m_model[index].tu;
        vertex1.tv = m_model[index].tv;
        index++;
        
        vertex2.x = m_model[index].x;
        vertex2.y = m_model[index].y;
        vertex2.z = m_model[index].z;
        vertex2.tu = m_model[index].tu;
        vertex2.tv = m_model[index].tv;
        index++;

        vertex3.x = m_model[index].x;
        vertex3.y = m_model[index].y;
        vertex3.z = m_model[index].z;
        vertex3.tu = m_model[index].tu;
        vertex3.tv = m_model[index].tv;
        index++;

        // Calculate the tangent and binormal of that face.
        CalculateTangentBinormal(vertex1, vertex2, vertex3, tangent, binormal);

        // Store the tangent and binormal for this face back in the model structure.
        m_model[index-1].tx = tangent.x;
        m_model[index-1].ty = tangent.y;
        m_model[index-1].tz = tangent.z;
        m_model[index-1].bx = binormal.x;
        m_model[index-1].by = binormal.y;
        m_model[index-1].bz = binormal.z;

        m_model[index-2].tx = tangent.x;
        m_model[index-2].ty = tangent.y;
        m_model[index-2].tz = tangent.z;
        m_model[index-2].bx = binormal.x;
        m_model[index-2].by = binormal.y;
        m_model[index-2].bz = binormal.z;

        m_model[index-3].tx = tangent.x;
        m_model[index-3].ty = tangent.y;
        m_model[index-3].tz = tangent.z;
        m_model[index-3].bx = binormal.x;
        m_model[index-3].by = binormal.y;
        m_model[index-3].bz = binormal.z;
    }

    return;
}


void ModelClass::CalculateTangentBinormal(TempVertexType vertex1, TempVertexType vertex2, TempVertexType vertex3, VectorType& tangent, VectorType& binormal)
{
    float vector1[3], vector2[3];
    float tuVector[2], tvVector[2];
    float den;
    float length;


    // Calculate the two vectors for this face.
    vector1[0] = vertex2.x - vertex1.x;
    vector1[1] = vertex2.y - vertex1.y;
    vector1[2] = vertex2.z - vertex1.z;

    vector2[0] = vertex3.x - vertex1.x;
    vector2[1] = vertex3.y - vertex1.y;
    vector2[2] = vertex3.z - vertex1.z;

    // Calculate the tu and tv texture space vectors.
    tuVector[0] = vertex2.tu - vertex1.tu;
    tvVector[0] = vertex2.tv - vertex1.tv;

    tuVector[1] = vertex3.tu - vertex1.tu;
    tvVector[1] = vertex3.tv - vertex1.tv;

    // Calculate the denominator of the tangent/binormal equation.
    den = 1.0f / (tuVector[0] * tvVector[1] - tuVector[1] * tvVector[0]);

    // Calculate the cross products and multiply by the coefficient to get the tangent and binormal.
    tangent.x = (tvVector[1] * vector1[0] - tvVector[0] * vector2[0]) * den;
    tangent.y = (tvVector[1] * vector1[1] - tvVector[0] * vector2[1]) * den;
    tangent.z = (tvVector[1] * vector1[2] - tvVector[0] * vector2[2]) * den;

    binormal.x = (tuVector[0] * vector2[0] - tuVector[1] * vector1[0]) * den;
    binormal.y = (tuVector[0] * vector2[1] - tuVector[1] * vector1[1]) * den;
    binormal.z = (tuVector[0] * vector2[2] - tuVector[1] * vector1[2]) * den;

    // Calculate the length of this normal.
    length = sqrt((tangent.x * tangent.x) + (tangent.y * tangent.y) + (tangent.z * tangent.z));

    // Normalize the normal and then store it
    tangent.x = tangent.x / length;
    tangent.y = tangent.y / length;
    tangent.z = tangent.z / length;

    // Calculate the length of this normal.
    length = sqrt((binormal.x * binormal.x) + (binormal.y * binormal.y) + (binormal.z * binormal.z));

    // Normalize the normal and then store it
    binormal.x = binormal.x / length;
    binormal.y = binormal.y / length;
    binormal.z = binormal.z / length;

    return;
}