// Demeter Terrain Visualization Library by Clay Fowler
// Copyright (C) 2001 Clay Fowler

/*
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; either
version 2.1 of the License, or (at your option) any later version.

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
Library General Public License for more details.

You should have received a copy of the GNU Library General Public
License along with this library; if not, write to the
Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA  02111-1307, USA.
*/

#include "Matrix.h"

using namespace Demeter;

inline float &Matrix::operator() (int i, int j)
{
	return m_Elements[i][j];
}

inline const float &Matrix::operator() (int i, int j)
     const
     {
	     return m_Elements[i][j];
     }

     void Matrix::SetIdentity()
{
	m_Elements[0][0] = 1.0f;
	m_Elements[0][1] = 0.0f;
	m_Elements[0][2] = 0.0f;
	m_Elements[0][3] = 0.0f;

	m_Elements[1][0] = 0.0f;
	m_Elements[1][1] = 1.0f;
	m_Elements[1][2] = 0.0f;
	m_Elements[1][3] = 0.0f;

	m_Elements[2][0] = 0.0f;
	m_Elements[2][1] = 0.0f;
	m_Elements[2][2] = 1.0f;
	m_Elements[2][3] = 0.0f;

	m_Elements[3][0] = 0.0f;
	m_Elements[3][1] = 0.0f;
	m_Elements[3][2] = 0.0f;
	m_Elements[3][3] = 1.0f;
}

void Matrix::SetRotateZ(float theta)
{
	SetIdentity();
	m_Elements[0][0] = (float)cos(theta);
	m_Elements[0][1] = (float)sin(theta);
	m_Elements[1][0] = -(float)sin(theta);
	m_Elements[1][1] = (float)cos(theta);
}

void Matrix::SetRotateX(float theta)
{
	SetIdentity();
	m_Elements[1][1] = (float)cos(theta);
	m_Elements[1][2] = (float)sin(theta);
	m_Elements[2][1] = -(float)sin(theta);
	m_Elements[2][2] = (float)cos(theta);
}

void Matrix::SetRotateY(float theta)
{
	SetIdentity();
	m_Elements[0][0] = (float)cos(theta);
	m_Elements[0][2] = -(float)sin(theta);
	m_Elements[2][0] = (float)sin(theta);
	m_Elements[2][2] = (float)cos(theta);
}

Matrix Matrix::operator *(const Matrix & matOther)
{
	long int i, j;
	Matrix matResult;
	Matrix & matThis = *this;

	for (i = 0; i <= 3; i++)
	{
		for (j = 0; j <= 3; j++)
		{
			matResult(i, j) = matThis(i, 0) * matOther(0, j) + matThis(i, 1) * matOther(1, j) + matThis(i, 2) * matOther(2, j) + matThis(i, 3) * matOther(3, j);
		}
	}

	return matResult;
}

Vector Matrix::operator *(const Vector & v)
{
	Vector vResult;
	Matrix & matThis = *this;

	vResult.x = v.x * matThis(0, 0) + v.y * matThis(1, 0) + v.z * matThis(2, 0);
	vResult.y = v.x * matThis(0, 1) + v.y * matThis(1, 1) + v.z * matThis(2, 1);
	vResult.z = v.z * matThis(0, 2) + v.y * matThis(1, 2) + v.z * matThis(2, 2);

	return vResult;
}