import * as glMatrix from "./common.js";
/**
* 2 Dimensional Vector
* @module vec2
*/
/**
* Creates a new, empty vec2
*
* @returns {vec2} a new 2D vector
*/
export function create() {
let out = new glMatrix.ARRAY_TYPE(2);
out[0] = 0;
out[1] = 0;
return out;
}
/**
* Creates a new vec2 initialized with values from an existing vector
*
* @param {vec2} a vector to clone
* @returns {vec2} a new 2D vector
*/
export function clone(a) {
let out = new glMatrix.ARRAY_TYPE(2);
out[0] = a[0];
out[1] = a[1];
return out;
}
/**
* Creates a new vec2 initialized with the given values
*
* @param {Number} x X component
* @param {Number} y Y component
* @returns {vec2} a new 2D vector
*/
export function fromValues(x, y) {
let out = new glMatrix.ARRAY_TYPE(2);
out[0] = x;
out[1] = y;
return out;
}
/**
* Copy the values from one vec2 to another
*
* @param {vec2} out the receiving vector
* @param {vec2} a the source vector
* @returns {vec2} out
*/
export function copy(out, a) {
out[0] = a[0];
out[1] = a[1];
return out;
}
/**
* Set the components of a vec2 to the given values
*
* @param {vec2} out the receiving vector
* @param {Number} x X component
* @param {Number} y Y component
* @returns {vec2} out
*/
export function set(out, x, y) {
out[0] = x;
out[1] = y;
return out;
}
/**
* Adds two vec2's
*
* @param {vec2} out the receiving vector
* @param {vec2} a the first operand
* @param {vec2} b the second operand
* @returns {vec2} out
*/
export function add(out, a, b) {
out[0] = a[0] + b[0];
out[1] = a[1] + b[1];
return out;
}
/**
* Subtracts vector b from vector a
*
* @param {vec2} out the receiving vector
* @param {vec2} a the first operand
* @param {vec2} b the second operand
* @returns {vec2} out
*/
export function subtract(out, a, b) {
out[0] = a[0] - b[0];
out[1] = a[1] - b[1];
return out;
}
/**
* Multiplies two vec2's
*
* @param {vec2} out the receiving vector
* @param {vec2} a the first operand
* @param {vec2} b the second operand
* @returns {vec2} out
*/
export function multiply(out, a, b) {
out[0] = a[0] * b[0];
out[1] = a[1] * b[1];
return out;
}
/**
* Divides two vec2's
*
* @param {vec2} out the receiving vector
* @param {vec2} a the first operand
* @param {vec2} b the second operand
* @returns {vec2} out
*/
export function divide(out, a, b) {
out[0] = a[0] / b[0];
out[1] = a[1] / b[1];
return out;
}
/**
* Math.ceil the components of a vec2
*
* @param {vec2} out the receiving vector
* @param {vec2} a vector to ceil
* @returns {vec2} out
*/
export function ceil(out, a) {
out[0] = Math.ceil(a[0]);
out[1] = Math.ceil(a[1]);
return out;
}
/**
* Math.floor the components of a vec2
*
* @param {vec2} out the receiving vector
* @param {vec2} a vector to floor
* @returns {vec2} out
*/
export function floor(out, a) {
out[0] = Math.floor(a[0]);
out[1] = Math.floor(a[1]);
return out;
}
/**
* Returns the minimum of two vec2's
*
* @param {vec2} out the receiving vector
* @param {vec2} a the first operand
* @param {vec2} b the second operand
* @returns {vec2} out
*/
export function min(out, a, b) {
out[0] = Math.min(a[0], b[0]);
out[1] = Math.min(a[1], b[1]);
return out;
}
/**
* Returns the maximum of two vec2's
*
* @param {vec2} out the receiving vector
* @param {vec2} a the first operand
* @param {vec2} b the second operand
* @returns {vec2} out
*/
export function max(out, a, b) {
out[0] = Math.max(a[0], b[0]);
out[1] = Math.max(a[1], b[1]);
return out;
}
/**
* Math.round the components of a vec2
*
* @param {vec2} out the receiving vector
* @param {vec2} a vector to round
* @returns {vec2} out
*/
export function round (out, a) {
out[0] = Math.round(a[0]);
out[1] = Math.round(a[1]);
return out;
}
/**
* Scales a vec2 by a scalar number
*
* @param {vec2} out the receiving vector
* @param {vec2} a the vector to scale
* @param {Number} b amount to scale the vector by
* @returns {vec2} out
*/
export function scale(out, a, b) {
out[0] = a[0] * b;
out[1] = a[1] * b;
return out;
}
/**
* Adds two vec2's after scaling the second operand by a scalar value
*
* @param {vec2} out the receiving vector
* @param {vec2} a the first operand
* @param {vec2} b the second operand
* @param {Number} scale the amount to scale b by before adding
* @returns {vec2} out
*/
export function scaleAndAdd(out, a, b, scale) {
out[0] = a[0] + (b[0] * scale);
out[1] = a[1] + (b[1] * scale);
return out;
}
/**
* Calculates the euclidian distance between two vec2's
*
* @param {vec2} a the first operand
* @param {vec2} b the second operand
* @returns {Number} distance between a and b
*/
export function distance(a, b) {
var x = b[0] - a[0],
y = b[1] - a[1];
return Math.sqrt(x*x + y*y);
}
/**
* Calculates the squared euclidian distance between two vec2's
*
* @param {vec2} a the first operand
* @param {vec2} b the second operand
* @returns {Number} squared distance between a and b
*/
export function squaredDistance(a, b) {
var x = b[0] - a[0],
y = b[1] - a[1];
return x*x + y*y;
}
/**
* Calculates the length of a vec2
*
* @param {vec2} a vector to calculate length of
* @returns {Number} length of a
*/
export function length(a) {
var x = a[0],
y = a[1];
return Math.sqrt(x*x + y*y);
}
/**
* Calculates the squared length of a vec2
*
* @param {vec2} a vector to calculate squared length of
* @returns {Number} squared length of a
*/
export function squaredLength (a) {
var x = a[0],
y = a[1];
return x*x + y*y;
}
/**
* Negates the components of a vec2
*
* @param {vec2} out the receiving vector
* @param {vec2} a vector to negate
* @returns {vec2} out
*/
export function negate(out, a) {
out[0] = -a[0];
out[1] = -a[1];
return out;
}
/**
* Returns the inverse of the components of a vec2
*
* @param {vec2} out the receiving vector
* @param {vec2} a vector to invert
* @returns {vec2} out
*/
export function inverse(out, a) {
out[0] = 1.0 / a[0];
out[1] = 1.0 / a[1];
return out;
}
/**
* Normalize a vec2
*
* @param {vec2} out the receiving vector
* @param {vec2} a vector to normalize
* @returns {vec2} out
*/
export function normalize(out, a) {
var x = a[0],
y = a[1];
var len = x*x + y*y;
if (len > 0) {
//TODO: evaluate use of glm_invsqrt here?
len = 1 / Math.sqrt(len);
out[0] = a[0] * len;
out[1] = a[1] * len;
}
return out;
}
/**
* Calculates the dot product of two vec2's
*
* @param {vec2} a the first operand
* @param {vec2} b the second operand
* @returns {Number} dot product of a and b
*/
export function dot(a, b) {
return a[0] * b[0] + a[1] * b[1];
}
/**
* Computes the cross product of two vec2's
* Note that the cross product must by definition produce a 3D vector
*
* @param {vec3} out the receiving vector
* @param {vec2} a the first operand
* @param {vec2} b the second operand
* @returns {vec3} out
*/
export function cross(out, a, b) {
var z = a[0] * b[1] - a[1] * b[0];
out[0] = out[1] = 0;
out[2] = z;
return out;
}
/**
* Performs a linear interpolation between two vec2's
*
* @param {vec2} out the receiving vector
* @param {vec2} a the first operand
* @param {vec2} b the second operand
* @param {Number} t interpolation amount, in the range [0-1], between the two inputs
* @returns {vec2} out
*/
export function lerp(out, a, b, t) {
var ax = a[0],
ay = a[1];
out[0] = ax + t * (b[0] - ax);
out[1] = ay + t * (b[1] - ay);
return out;
}
/**
* Generates a random vector with the given scale
*
* @param {vec2} out the receiving vector
* @param {Number} [scale] Length of the resulting vector. If ommitted, a unit vector will be returned
* @returns {vec2} out
*/
export function random(out, scale) {
scale = scale || 1.0;
var r = glMatrix.RANDOM() * 2.0 * Math.PI;
out[0] = Math.cos(r) * scale;
out[1] = Math.sin(r) * scale;
return out;
}
/**
* Transforms the vec2 with a mat2
*
* @param {vec2} out the receiving vector
* @param {vec2} a the vector to transform
* @param {mat2} m matrix to transform with
* @returns {vec2} out
*/
export function transformMat2(out, a, m) {
var x = a[0],
y = a[1];
out[0] = m[0] * x + m[2] * y;
out[1] = m[1] * x + m[3] * y;
return out;
}
/**
* Transforms the vec2 with a mat2d
*
* @param {vec2} out the receiving vector
* @param {vec2} a the vector to transform
* @param {mat2d} m matrix to transform with
* @returns {vec2} out
*/
export function transformMat2d(out, a, m) {
var x = a[0],
y = a[1];
out[0] = m[0] * x + m[2] * y + m[4];
out[1] = m[1] * x + m[3] * y + m[5];
return out;
}
/**
* Transforms the vec2 with a mat3
* 3rd vector component is implicitly '1'
*
* @param {vec2} out the receiving vector
* @param {vec2} a the vector to transform
* @param {mat3} m matrix to transform with
* @returns {vec2} out
*/
export function transformMat3(out, a, m) {
var x = a[0],
y = a[1];
out[0] = m[0] * x + m[3] * y + m[6];
out[1] = m[1] * x + m[4] * y + m[7];
return out;
}
/**
* Transforms the vec2 with a mat4
* 3rd vector component is implicitly '0'
* 4th vector component is implicitly '1'
*
* @param {vec2} out the receiving vector
* @param {vec2} a the vector to transform
* @param {mat4} m matrix to transform with
* @returns {vec2} out
*/
export function transformMat4(out, a, m) {
let x = a[0];
let y = a[1];
out[0] = m[0] * x + m[4] * y + m[12];
out[1] = m[1] * x + m[5] * y + m[13];
return out;
}
/**
* Rotate a 2D vector
* @param {vec2} out The receiving vec2
* @param {vec2} a The vec2 point to rotate
* @param {vec2} b The origin of the rotation
* @param {Number} c The angle of rotation
* @returns {vec2} out
*/
export function rotate(out, a, b, c) {
//Translate point to the origin
let p0 = a[0] - b[0],
p1 = a[1] - b[1],
sinC = Math.sin(c),
cosC = Math.cos(c);
//perform rotation and translate to correct position
out[0] = p0*cosC - p1*sinC + b[0];
out[1] = p0*sinC + p1*cosC + b[1];
return out;
}
/**
* Get the angle between two 2D vectors
* @param {vec2} a The first operand
* @param {vec2} b The second operand
* @returns {Number} The angle in radians
*/
export function angle(a, b) {
let x1 = a[0],
y1 = a[1],
x2 = b[0],
y2 = b[1];
let len1 = x1*x1 + y1*y1;
if (len1 > 0) {
//TODO: evaluate use of glm_invsqrt here?
len1 = 1 / Math.sqrt(len1);
}
let len2 = x2*x2 + y2*y2;
if (len2 > 0) {
//TODO: evaluate use of glm_invsqrt here?
len2 = 1 / Math.sqrt(len2);
}
let cosine = (x1 * x2 + y1 * y2) * len1 * len2;
if(cosine > 1.0) {
return 0;
}
else if(cosine < -1.0) {
return Math.PI;
} else {
return Math.acos(cosine);
}
}
/**
* Returns a string representation of a vector
*
* @param {vec2} a vector to represent as a string
* @returns {String} string representation of the vector
*/
export function str(a) {
return 'vec2(' + a[0] + ', ' + a[1] + ')';
}
/**
* Returns whether or not the vectors exactly have the same elements in the same position (when compared with ===)
*
* @param {vec2} a The first vector.
* @param {vec2} b The second vector.
* @returns {Boolean} True if the vectors are equal, false otherwise.
*/
export function exactEquals(a, b) {
return a[0] === b[0] && a[1] === b[1];
}
/**
* Returns whether or not the vectors have approximately the same elements in the same position.
*
* @param {vec2} a The first vector.
* @param {vec2} b The second vector.
* @returns {Boolean} True if the vectors are equal, false otherwise.
*/
export function equals(a, b) {
let a0 = a[0], a1 = a[1];
let b0 = b[0], b1 = b[1];
return (Math.abs(a0 - b0) <= glMatrix.EPSILON*Math.max(1.0, Math.abs(a0), Math.abs(b0)) &&
Math.abs(a1 - b1) <= glMatrix.EPSILON*Math.max(1.0, Math.abs(a1), Math.abs(b1)));
}
/**
* Alias for {@link vec2.length}
* @function
*/
export const len = length;
/**
* Alias for {@link vec2.subtract}
* @function
*/
export const sub = subtract;
/**
* Alias for {@link vec2.multiply}
* @function
*/
export const mul = multiply;
/**
* Alias for {@link vec2.divide}
* @function
*/
export const div = divide;
/**
* Alias for {@link vec2.distance}
* @function
*/
export const dist = distance;
/**
* Alias for {@link vec2.squaredDistance}
* @function
*/
export const sqrDist = squaredDistance;
/**
* Alias for {@link vec2.squaredLength}
* @function
*/
export const sqrLen = squaredLength;
/**
* Perform some operation over an array of vec2s.
*
* @param {Array} a the array of vectors to iterate over
* @param {Number} stride Number of elements between the start of each vec2. If 0 assumes tightly packed
* @param {Number} offset Number of elements to skip at the beginning of the array
* @param {Number} count Number of vec2s to iterate over. If 0 iterates over entire array
* @param {Function} fn Function to call for each vector in the array
* @param {Object} [arg] additional argument to pass to fn
* @returns {Array} a
* @function
*/
export const forEach = (function() {
let vec = create();
return function(a, stride, offset, count, fn, arg) {
let i, l;
if(!stride) {
stride = 2;
}
if(!offset) {
offset = 0;
}
if(count) {
l = Math.min((count * stride) + offset, a.length);
} else {
l = a.length;
}
for(i = offset; i < l; i += stride) {
vec[0] = a[i]; vec[1] = a[i+1];
fn(vec, vec, arg);
a[i] = vec[0]; a[i+1] = vec[1];
}
return a;
};
})();