define([], function () {
"use strict";
/**
* Mat2 - 2x2 Matrix
* Any javascript array containing at least 4 numeric elements can serve as a mat2, however creating matrices
* using Mat2 constructor functions will use Float32Array
* @class Mat2
* @namespace kick.math
*/
return {
/**
* Creates a new instance of a mat2 using Float32Array<br>
*
* @method create
* @return {kick.math.Mat2} New mat2
* @static
*/
create: function () {
var out = new Float32Array(4);
out[0] = 1;
out[3] = 1;
return out;
},
/**
* Creates a new mat2 initialized with values from an existing matrix
* @method clone
* @param {kick.math.Mat2} a matrix to clone
* @return {kick.math.Mat2} a new 2x2 matrix
* @static
*/
clone: function (a) {
var out = new Float32Array(4);
out[0] = a[0];
out[1] = a[1];
out[2] = a[2];
out[3] = a[3];
return out;
},
/**
* Copies the values of one mat3 to another
* @method copy
* @param {kick.math.Mat2} out the receiving matrix
* @param {kick.math.Mat2} a the source matrix
* @return {kick.math.Mat2} out
* @static
*/
copy: function (out, a) {
out[0] = a[0];
out[1] = a[1];
out[2] = a[2];
out[3] = a[3];
return out;
},
/**
* Sets a Mat2 to the identity matrix
* @method identity
* @param {kick.math.Mat2} out the receiving matrix
* @return {kick.math.Mat2} out
* @static
*/
identity: function (out) {
out[0] = 1;
out[1] = 0;
out[2] = 0;
out[3] = 1;
return out;
},
/**
* Transposes a Mat2 (flips the values over the diagonal)
* @method transpose
* @param {kick.math.Mat2} out the receiving matrix
* @param {kick.math.Mat2} a the source matrix
* @return {kick.math.Mat2} out
* @static
*/
transpose: function (out, a) {
// If we are transposing ourselves we can skip a few steps but have to cache some values
if (out === a) {
var a1 = a[1];
out[1] = a[2];
out[2] = a1;
} else {
out[0] = a[0];
out[1] = a[2];
out[2] = a[1];
out[3] = a[3];
}
return out;
},
/**
* Inverts a Mat2
* @method invert
* @param {kick.math.Mat2} out the receiving matrix
* @param {kick.math.Mat2} a the source matrix
* @return {kick.math.Mat2} out
* @static
*/
invert: function (out, a) {
var a0 = a[0], a1 = a[1], a2 = a[2], a3 = a[3],
// Calculate the determinant
det = a0 * a3 - a2 * a1;
if (!det) {
return null;
}
det = 1.0 / det;
out[0] = a3 * det;
out[1] = -a1 * det;
out[2] = -a2 * det;
out[3] = a0 * det;
return out;
},
/**
* Calculates the adjugate of a mat2
* @method adjoint
* @param {kick.math.Mat2} out the receiving matrix
* @param {kick.math.Mat2} a the source matrix
* @return {kick.math.Mat2} out
* @static
*/
adjoint: function (out, a) {
// Caching this value is nessecary if out == a
var a0 = a[0];
out[0] = a[3];
out[1] = -a[1];
out[2] = -a[2];
out[3] = a0;
return out;
},
/**
* Calculates the determinant of a Mat2
* @method determinant
* @param {kick.math.Mat2} a the source matrix
* @return {Number} determinant of a
* @static
*/
determinant: function (a) {
return a[0] * a[3] - a[2] * a[1];
},
/**
* Multiplies two Mat2's
* @method multiply
* @param {kick.math.Mat2} out the receiving matrix
* @param {kick.math.Mat2} a the first operand
* @param {kick.math.Mat2} b the second operand
* @return {kick.math.Mat2} out
* @static
*/
multiply: function (out, a, b) {
var a0 = a[0], a1 = a[1], a2 = a[2], a3 = a[3],
b0 = b[0], b1 = b[1], b2 = b[2], b3 = b[3];
out[0] = a0 * b0 + a1 * b2;
out[1] = a0 * b1 + a1 * b3;
out[2] = a2 * b0 + a3 * b2;
out[3] = a2 * b1 + a3 * b3;
return out;
},
/**
* Rotates a mat2 by the given angle
* @method rotate
* @param {kick.math.Mat2} out the receiving matrix
* @param {kick.math.Mat2} a the matrix to rotate
* @param {Number} rad the angle to rotate the matrix by
* @return {kick.math.Mat2} out
* @static
*/
rotate: function (out, a, rad) {
var a0 = a[0], a1 = a[1], a2 = a[2], a3 = a[3],
s = Math.sin(rad),
c = Math.cos(rad);
out[0] = a0 * c + a1 * s;
out[1] = a0 * -s + a1 * c;
out[2] = a2 * c + a3 * s;
out[3] = a2 * -s + a3 * c;
return out;
},
/**
* Scales the mat2 by the dimensions in the given vec2
* @method scale
* @param {kick.math.Mat2} out the receiving matrix
* @param {kick.math.Mat2} a the matrix to rotate
* @param {kick.math.Vec2} v the vec2 to scale the matrix by
* @return {kick.math.Mat2} out
* @static
**/
scale: function (out, a, v) {
var a0 = a[0], a1 = a[1], a2 = a[2], a3 = a[3],
v0 = v[0], v1 = v[1];
out[0] = a0 * v0;
out[1] = a1 * v1;
out[2] = a2 * v0;
out[3] = a3 * v1;
return out;
},
/**
* Returns a string representation of a Mat2
* @method str
* @param {kick.math.Mat2} a matrix to represent as a string
* @return {String} string representation of the matrix
* @static
*/
str: function (a) {
return '[' + a[0] + ', ' + a[1] + ', ' + a[2] + ', ' + a[3] + ']';
},
/**
* Returns a string representation of a Mat2 printed as a 2x2 matrix (on 2 lines)
* @method strPretty
* @param {kick.math.Mat2} mat mat2 to represent as a string
* @return {String} string representation of mat
* @static
*/
strPretty: function (mat) {
return '[' + mat[0] + ', ' + mat[2] + '\n' +
', ' + mat[1] + ', ' + mat[3] + ']';
}
};
});
