Matrix.cpp

/**
 *	File Matrix.cpp
 *	Description: implementation of Matrix class
 *
 */

#include "Matrix.hpp"
#include "Vector.hpp"


// construct an identity matrix as mat
Matrix::Matrix() {
	for (int i = 0; i < 4; i++) {
		for (int j = 0; j < 4; j++) {
			if (i == j)
				this->mat[i][j] = 1;
			else
				this->mat[i][j] = 0;
		}
	}
}

// multiplication  mat <- m * mat
void Matrix::matrix_pre_multiply(Matrix* m) {
	Matrix* temp = new Matrix();
	for (int i = 0; i < 4; i++) {
		for (int j = 0; j < 4; j++) {
			GLfloat sum = 0;
			for (int k = 0; k < 4; k++) {
				sum += m->mat[i][k] * this->mat[k][j];
			}
			temp->mat[i][j] = sum;
		}
	}
	for (int i = 0; i < 4; i++) {
		for (int j = 0; j < 4; j++) {
			this->mat[i][j] = temp->mat[i][j];
		}
	}
	delete temp;
}

// translate the origin of MC
void Matrix::translate(GLfloat tx, GLfloat ty, GLfloat tz) {
	this->mat[0][3] += tx;
	this->mat[1][3] += ty;
	this->mat[2][3] += tz;
	this->mat[3][3] = 1;
}

void Matrix::transpose() {

}

// normalize MC
void Matrix::normalize() {
	GLfloat norm;

	norm = sqrt(this->mat[0][0]*this->mat[0][0] + this->mat[1][0]*this->mat[1][0]+this->mat[2][0]*this->mat[2][0]);

	this->mat[0][0] = this->mat[0][0]/norm;
	this->mat[1][0] = this->mat[1][0]/norm;
	this->mat[2][0] = this->mat[2][0]/norm;

	this->mat[0][2] = this->mat[1][0]*this->mat[2][1]-this->mat[2][0]*this->mat[1][1];
	this->mat[1][2] = this->mat[2][0]*this->mat[0][1]-this->mat[0][0]*this->mat[2][1];
	this->mat[2][2] = this->mat[0][0]*this->mat[1][1]-this->mat[1][0]*this->mat[0][1];

	norm = sqrt(this->mat[0][2]*this->mat[0][2] + this->mat[1][2]*this->mat[1][2]+this->mat[2][2]*this->mat[2][2]);

	this->mat[0][2] = this->mat[0][2]/norm;
	this->mat[1][2] = this->mat[1][2]/norm;
	this->mat[2][2] = this->mat[2][2]/norm;

	this->mat[0][1] = this->mat[1][2]*this->mat[2][0]-this->mat[1][0]*this->mat[2][2];
	this->mat[1][1] = this->mat[2][2]*this->mat[0][0]-this->mat[2][0]*this->mat[0][2];
	this->mat[2][1] = this->mat[0][2]*this->mat[1][0]-this->mat[0][0]*this->mat[1][2];

	this->mat[3][0] = 0;
	this->mat[3][1] = 0;
	this->mat[3][2] = 0;
	this->mat[3][3] = 1;
}


// v  <- mat * v
void Matrix::multiply_vector(GLfloat* v) {

	GLfloat sum, temp[4];
	for( int i = 0; i < 4; i++ ) {
	sum = 0;
	for( int j = 0; j < 4; j++ ) {
	sum += v[j] * this->mat[i][j];
	}
	temp[i] = sum;
	}
	for( int i = 0; i < 4; i++ ) {
	v[i] = temp[i];
	}

}


// MC <= rotation matrix * MC, i.e., rotate cordinate vectors and the origin 
void Matrix::rotate(GLfloat x, GLfloat y, GLfloat z, GLfloat angle) {

	angle = angle * 3.1415926/180;
	float oneC = 1 - cos(angle);
	float COS = cos(angle);
	float SIN = sin(angle);

	Matrix* m = new Matrix();

	m->mat[0][0] = x * x * oneC + cos( angle );
	m->mat[0][1] = y * x * oneC + z * sin( angle );
	m->mat[0][2] = x * z * oneC - y * SIN;
	m->mat[0][3] = 0;

	m->mat[1][0] = x * y * oneC - z * SIN;
	m->mat[1][1] = y * y * oneC + COS;
	m->mat[1][2] = y * z * oneC + x * SIN;
	m->mat[1][3] = 0;

	m->mat[2][0] = x * z * oneC + y * SIN;
	m->mat[2][1] = y * z * oneC - x * SIN;
	m->mat[2][2] = z * z * oneC + COS;
	m->mat[2][3] = 0;

	m->mat[3][0] = 0;
	m->mat[3][1] = 0;
	m->mat[3][2] = 0;
	m->mat[3][3] = 1;

	this->matrix_pre_multiply(m);
	delete m;
}