Transitioning from scalar to vector

glv · November 23, 2021, 4:25am

Hello,

Some references for you to peruse:

processing/processing-android/blob/main/core/src/processing/core/PVector.java

/* -*- mode: java; c-basic-offset: 2; indent-tabs-mode: nil -*- */

/*
  Part of the Processing project - http://processing.org

  Copyright (c) 2012-21 The Processing Foundation
  Copyright (c) 2008-12 Ben Fry and Casey Reas
  Copyright (c) 2008 Dan Shiffman


  This library is free software; you can redistribute it and/or
  modify it under the terms of the GNU Lesser General Public
  License version 2.1 as published by the Free Software Foundation.

  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
  Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General

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https://natureofcode.com/book/chapter-1-vectors/

github.com

processing/p5.js/blob/main/src/math/p5.Vector.js

/**
 * @module Math
 * @submodule Vector
 * @requires constants
 */

import p5 from '../core/main';
import * as constants from '../core/constants';


/**
 * A class to describe a two or three-dimensional vector. A vector is like an
 * arrow pointing in space. Vectors have both magnitude (length) and
 * direction.
 *
 * `p5.Vector` objects are often used to program motion because they simplify
 * the math. For example, a moving ball has a position and a velocity.
 * Position describes where the ball is in space. The ball's position vector
 * extends from the origin to the ball's center. Velocity describes the ball's
 * speed and the direction it's moving. If the ball is moving straight up, its

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github.com/processing/p5.js

A few thoughts about p5.Vector implementation

opened 11:47AM - 28 Oct 17 UTC

closed 02:56AM - 07 Dec 17 UTC

tawez

I can make PR, but first I would like to discuss the list below. 1. Whenever… Vector instance is created with `new p5.Vector(...)`, the default value for x, y and z is 0. Then in every Vector method that accepts Vector as argument value, default 0 is applied again and again, for example: ```javascript p5.Vector.prototype.set = function (x, y, z) { if (x instanceof p5.Vector) { this.x = x.x || 0; this.y = x.y || 0; this.z = x.z || 0; return this; } ... }; ``` I think it is not necessary, because the default value is already there. 2. The default value of `n` in `p5.Vector.prototype.mult` is 0. When I call `mult` with no argument, my vector will be mutated. I think the default value of `n` should be 1. 3. We don't check if we divide by 0 in `p5.Vector.prototype.div`. There is a lot of validation in other methods, but not in `div`. Is it done by design? Checking divide by 0 case in `div` method would make `p5.Vector.prototype.normalize` a bit simpler. 4. Performance optimisations: - this.p5.random() => Math.random() - Math.PI*2 => constants.TWO_PI BTW. I can't get the fundamental difference between `if` and `else` parts, as the results seems to be the same, except the `if` part will be slower. ```javascript p5.Vector.random3D = function random3D() { ... if (this.p5) { angle = this.p5.random(0,constants.TWO_PI); vz = this.p5.random(-1,1); } else { angle = Math.random()*Math.PI*2; vz = Math.random()*2-1; } ... } ``` 5. Constructor could be much simpler if there were named arguments and different order of them. `function() => function(x, y, z, context)` ```javascript p5.Vector = function(x, y, z, context) { // This is how it comes in with createVector() if (context instanceof p5) { this.p5 = context; } this.x = x || 0; this.y = y || 0; this.z = z || 0; this.name = 'p5.Vector'; }; ``` This of course should be propagated in other places, but there is only a few such a cases. 6. Functions should be named. This will help during debugging. ```javascript // Bad example p5.Vector.prototype.set = function (x, y, z) {...} // Good example p5.Vector.prototype.set = function set(x, y, z) {...} // Still good, but over engineered example p5.Vector.prototype.set = function p5VectorSet(x, y, z) {...} ```

:)

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