From 66e291b57d595282dc47d23b522b3619e9e758ef Mon Sep 17 00:00:00 2001
From: liabru <liabru@brm.io>
Date: Fri, 2 Sep 2022 20:29:35 +0100
Subject: [PATCH] refactor body base delta constant

---
 src/body/Body.js | 34 ++++++++--------------------------
 1 file changed, 8 insertions(+), 26 deletions(-)

diff --git a/src/body/Body.js b/src/body/Body.js
index e2e07ce..ceba18d 100644
--- a/src/body/Body.js
+++ b/src/body/Body.js
@@ -25,25 +25,7 @@ var Axes = require('../geometry/Axes');
     Body._nextCollidingGroupId = 1;
     Body._nextNonCollidingGroupId = -1;
     Body._nextCategory = 0x0001;
-
-    /**
-     * The constant unit of time in milliseconds in relation to getting or setting body
-     * speed, velocity or force related properties or methods (except friction related).
-     * 
-     * This defaults to `1000 / 60` milliseconds.
-     * To use 1 second (as in the [SI base time unit](https://en.wikipedia.org/wiki/SI_base_unit)) then set this value to `1000`.
-     * 
-     * _Note about the default:_ For ease of use in browser games and compatibility with previous versions, the current default time unit 
-     * is chosen so that with the default engine delta `1000 / 60` milliseconds and default rendering at _1:1_, velocity matches _pixels_ per _frame_.
-     * 
-     * If your project requires real-world metrics or a different engine delta, consider using SI units shown above instead of this default.
-     *
-     * @static
-     * @property timeUnit
-     * @type number
-     * @default 1000 / 60
-     */
-    Body.timeUnit = 1000 / 60;
+    Body._baseDelta = 1000 / 60;
 
     /**
      * Creates a new rigid body model. The options parameter is an object that specifies any properties you wish to override the defaults.
@@ -551,7 +533,7 @@ var Axes = require('../geometry/Axes');
      * @param {vector} velocity
      */
     Body.setVelocity = function(body, velocity) {
-        var timeScale = body.deltaTime / Body.timeUnit;
+        var timeScale = body.deltaTime / Body._baseDelta;
         body.positionPrev.x = body.position.x - velocity.x * timeScale;
         body.positionPrev.y = body.position.y - velocity.y * timeScale;
         body.velocity.x = (body.position.x - body.positionPrev.x) / timeScale;
@@ -566,7 +548,7 @@ var Axes = require('../geometry/Axes');
      * @return {vector} velocity
      */
     Body.getVelocity = function(body) {
-        var timeScale = Body.timeUnit / body.deltaTime;
+        var timeScale = Body._baseDelta / body.deltaTime;
 
         return {
             x: (body.position.x - body.positionPrev.x) * timeScale,
@@ -604,7 +586,7 @@ var Axes = require('../geometry/Axes');
      * @param {number} velocity
      */
     Body.setAngularVelocity = function(body, velocity) {
-        var timeScale = body.deltaTime / Body.timeUnit;
+        var timeScale = body.deltaTime / Body._baseDelta;
         body.anglePrev = body.angle - velocity * timeScale;
         body.angularVelocity = (body.angle - body.anglePrev) / timeScale;
         body.angularSpeed = Math.abs(body.angularVelocity);
@@ -617,7 +599,7 @@ var Axes = require('../geometry/Axes');
      * @return {number} angular velocity
      */
     Body.getAngularVelocity = function(body) {
-        return (body.angle - body.anglePrev) * Body.timeUnit / body.deltaTime;
+        return (body.angle - body.anglePrev) * Body._baseDelta / body.deltaTime;
     };
 
     /**
@@ -802,12 +784,12 @@ var Axes = require('../geometry/Axes');
     };
 
     /**
-     * Updates properties `body.velocity`, `body.speed`, `body.angularVelocity` and `body.angularSpeed` which are normalised in relation to `Body.timeUnit`.
+     * Updates properties `body.velocity`, `body.speed`, `body.angularVelocity` and `body.angularSpeed` which are normalised in relation to `Body._baseDelta`.
      * @method updateVelocities
      * @param {body} body
      */
     Body.updateVelocities = function(body) {
-        var timeScale = Body.timeUnit / body.deltaTime,
+        var timeScale = Body._baseDelta / body.deltaTime,
             bodyVelocity = body.velocity;
 
         bodyVelocity.x = (body.position.x - body.positionPrev.x) * timeScale;
@@ -831,7 +813,7 @@ var Axes = require('../geometry/Axes');
      * @param {vector} force
      */
     Body.applyForce = function(body, position, force) {
-        var timeScale = body.deltaTime / Body.timeUnit;
+        var timeScale = body.deltaTime / Body._baseDelta;
         body.force.x += force.x / timeScale;
         body.force.y += force.y / timeScale;
         var offset = { x: position.x - body.position.x, y: position.y - body.position.y };