From 83e46c00a65b6e4cd19821fe75cd8d498662306b Mon Sep 17 00:00:00 2001
From: Mojtaba Javan <javan.mojtaba@gmail.com>
Date: Wed, 8 Apr 2020 20:26:22 +0430
Subject: [PATCH] Change mouse.position to mouse.absolute

When using a device with `devicePixelRatio` other than 1 and applying `pixelRatio` on Renderer (e.g. `pixelRatio: "auto"`), mouse constraints don't behave correctly. They use `mouse.position` which is a relative position, so, for example, dragging an elastic object on such devices wouldn't occur at the object's location.

**How to produce**:
Try [slingshot demo](https://brm.io/matter-js/demo/#slingshot) on a mobile device with a pixel ratio other than 1.
---
 src/constraint/MouseConstraint.js | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/src/constraint/MouseConstraint.js b/src/constraint/MouseConstraint.js
index 4dc5561..ec280a3 100644
--- a/src/constraint/MouseConstraint.js
+++ b/src/constraint/MouseConstraint.js
@@ -48,7 +48,7 @@ var Bounds = require('../geometry/Bounds');
 
         var constraint = Constraint.create({ 
             label: 'Mouse Constraint',
-            pointA: mouse.position,
+            pointA: mouse.absolute,
             pointB: { x: 0, y: 0 },
             length: 0.01, 
             stiffness: 0.1,
@@ -99,14 +99,14 @@ var Bounds = require('../geometry/Bounds');
             if (!constraint.bodyB) {
                 for (var i = 0; i < bodies.length; i++) {
                     body = bodies[i];
-                    if (Bounds.contains(body.bounds, mouse.position) 
+                    if (Bounds.contains(body.bounds, mouse.absolute) 
                             && Detector.canCollide(body.collisionFilter, mouseConstraint.collisionFilter)) {
                         for (var j = body.parts.length > 1 ? 1 : 0; j < body.parts.length; j++) {
                             var part = body.parts[j];
-                            if (Vertices.contains(part.vertices, mouse.position)) {
-                                constraint.pointA = mouse.position;
+                            if (Vertices.contains(part.vertices, mouse.absolute)) {
+                                constraint.pointA = mouse.absolute;
                                 constraint.bodyB = mouseConstraint.body = body;
-                                constraint.pointB = { x: mouse.position.x - body.position.x, y: mouse.position.y - body.position.y };
+                                constraint.pointB = { x: mouse.absolute.x - body.position.x, y: mouse.absolute.y - body.position.y };
                                 constraint.angleB = body.angle;
 
                                 Sleeping.set(body, false);
@@ -119,7 +119,7 @@ var Bounds = require('../geometry/Bounds');
                 }
             } else {
                 Sleeping.set(constraint.bodyB, false);
-                constraint.pointA = mouse.position;
+                constraint.pointA = mouse.absolute;
             }
         } else {
             constraint.bodyB = mouseConstraint.body = null;