love2d.love/src/common/Matrix.cpp

/**
 * Copyright (c) 2006-2012 LOVE Development Team
 *
 * This software is provided 'as-is', without any express or implied
 * warranty.  In no event will the authors be held liable for any damages
 * arising from the use of this software.
 *
 * Permission is granted to anyone to use this software for any purpose,
 * including commercial applications, and to alter it and redistribute it
 * freely, subject to the following restrictions:
 *
 * 1. The origin of this software must not be misrepresented; you must not
 *    claim that you wrote the original software. If you use this software
 *    in a product, an acknowledgment in the product documentation would be
 *    appreciated but is not required.
 * 2. Altered source versions must be plainly marked as such, and must not be
 *    misrepresented as being the original software.
 * 3. This notice may not be removed or altered from any source distribution.
 **/

#include "Matrix.h"

// STD
#include <cstring> // memcpy
#include <cmath>

namespace love
{

// | e0 e4 e8  e12 |
// | e1 e5 e9  e13 |
// | e2 e6 e10 e14 |
// | e3 e7 e11 e15 |

Matrix::Matrix()
{
	setIdentity();
}

Matrix::~Matrix()
{
}

//                 | e0 e4 e8  e12 |
//                 | e1 e5 e9  e13 |
//                 | e2 e6 e10 e14 |
//                 | e3 e7 e11 e15 |
// | e0 e4 e8  e12 |
// | e1 e5 e9  e13 |
// | e2 e6 e10 e14 |
// | e3 e7 e11 e15 |

Matrix Matrix::operator * (const Matrix &m) const
{
	Matrix t;

	t.e[0] = (e[0]*m.e[0]) + (e[4]*m.e[1]) + (e[8]*m.e[2]) + (e[12]*m.e[3]);
	t.e[4] = (e[0]*m.e[4]) + (e[4]*m.e[5]) + (e[8]*m.e[6]) + (e[12]*m.e[7]);
	t.e[8] = (e[0]*m.e[8]) + (e[4]*m.e[9]) + (e[8]*m.e[10]) + (e[12]*m.e[11]);
	t.e[12] = (e[0]*m.e[12]) + (e[4]*m.e[13]) + (e[8]*m.e[14]) + (e[12]*m.e[15]);

	t.e[1] = (e[1]*m.e[0]) + (e[5]*m.e[1]) + (e[9]*m.e[2]) + (e[13]*m.e[3]);
	t.e[5] = (e[1]*m.e[4]) + (e[5]*m.e[5]) + (e[9]*m.e[6]) + (e[13]*m.e[7]);
	t.e[9] = (e[1]*m.e[8]) + (e[5]*m.e[9]) + (e[9]*m.e[10]) + (e[13]*m.e[11]);
	t.e[13] = (e[1]*m.e[12]) + (e[5]*m.e[13]) + (e[9]*m.e[14]) + (e[13]*m.e[15]);

	t.e[2] = (e[2]*m.e[0]) + (e[6]*m.e[1]) + (e[10]*m.e[2]) + (e[14]*m.e[3]);
	t.e[6] = (e[2]*m.e[4]) + (e[6]*m.e[5]) + (e[10]*m.e[6]) + (e[14]*m.e[7]);
	t.e[10] = (e[2]*m.e[8]) + (e[6]*m.e[9]) + (e[10]*m.e[10]) + (e[14]*m.e[11]);
	t.e[14] = (e[2]*m.e[12]) + (e[6]*m.e[13]) + (e[10]*m.e[14]) + (e[14]*m.e[15]);

	t.e[3] = (e[3]*m.e[0]) + (e[7]*m.e[1]) + (e[11]*m.e[2]) + (e[15]*m.e[3]);
	t.e[7] = (e[3]*m.e[4]) + (e[7]*m.e[5]) + (e[11]*m.e[6]) + (e[15]*m.e[7]);
	t.e[11] = (e[3]*m.e[8]) + (e[7]*m.e[9]) + (e[11]*m.e[10]) + (e[15]*m.e[11]);
	t.e[15] = (e[3]*m.e[12]) + (e[7]*m.e[13]) + (e[11]*m.e[14]) + (e[15]*m.e[15]);

	return t;
}

void Matrix::operator *= (const Matrix &m)
{
	Matrix t = (*this) * m;
	memcpy((void *)this->e, (void *)t.e, sizeof(float)*16);
}

const float *Matrix::getElements() const
{
	return e;
}

void Matrix::setIdentity()
{
	memset(e, 0, sizeof(float)*16);
	e[0] = e[5] = e[10] = e[15] = 1;
}

void Matrix::setTranslation(float x, float y)
{
	setIdentity();
	e[12] = x;
	e[13] = y;
}

void Matrix::setRotation(float rad)
{
	setIdentity();
	float c = cos(rad), s = sin(rad);
	e[0] = c;
	e[4] = -s;
	e[1] = s;
	e[5] = c;
}

void Matrix::setScale(float sx, float sy)
{
	setIdentity();
	e[0] = sx;
	e[5] = sy;
}

void Matrix::setShear(float kx, float ky)
{
	setIdentity();
	e[1] = ky;
	e[4] = kx;
}

void Matrix::setTransformation(float x, float y, float angle, float sx, float sy, float ox, float oy, float kx, float ky)
{
	memset(e, 0, sizeof(float)*16); // zero out matrix
	float c = cos(angle), s = sin(angle);
	// matrix multiplication carried out on paper:
	// |1     x| |c -s    | |sx       | | 1 ky    | |1     -ox|
	// |  1   y| |s  c    | |   sy    | |kx  1    | |  1   -oy|
	// |    1  | |     1  | |      1  | |      1  | |    1    |
	// |      1| |       1| |        1| |        1| |       1 |
	//   move      rotate      scale       skew       origin
	e[10] = e[15] = 1.0f;
	e[0]  = c * sx - ky * s * sy; // = a
	e[1]  = s * sx + ky * c * sy; // = b
	e[4]  = kx * c * sx - s * sy; // = c
	e[5]  = kx * s * sx + c * sy; // = d
	e[12] = x - ox * e[0] - oy * e[4];
	e[13] = y - ox * e[1] - oy * e[5];
}

void Matrix::translate(float x, float y)
{
	Matrix t;
	t.setTranslation(x, y);
	this->operator *=(t);
}

void Matrix::rotate(float rad)
{
	Matrix t;
	t.setRotation(rad);
	this->operator *=(t);
}

void Matrix::scale(float sx, float sy)
{
	Matrix t;
	t.setScale(sx, sy);
	this->operator *=(t);
}

void Matrix::shear(float kx, float ky)
{
	Matrix t;
	t.setShear(kx,ky);
	this->operator *=(t);
}

//                 | x |
//                 | y |
//                 | 0 |
//                 | 1 |
// | e0 e4 e8  e12 |
// | e1 e5 e9  e13 |
// | e2 e6 e10 e14 |
// | e3 e7 e11 e15 |

void Matrix::transform(vertex *dst, const vertex *src, int size) const
{
	for (int i = 0; i<size; i++)
	{
		// Store in temp variables in case src = dst
		float x = (e[0]*src[i].x) + (e[4]*src[i].y) + (0) + (e[12]);
		float y = (e[1]*src[i].x) + (e[5]*src[i].y) + (0) + (e[13]);

		dst[i].x = x;
		dst[i].y = y;
	}
}


} // love