From 205aaa50660bb72ccd7ce62b2ce28648f0aa04aa Mon Sep 17 00:00:00 2001
From: liabru <liabru@brm.io>
Date: Sun, 22 Oct 2023 23:58:04 +0100
Subject: [PATCH] added Example.substep

---
 demo/src/Compare.js |   1 -
 examples/index.js   |   1 +
 examples/substep.js | 120 ++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 121 insertions(+), 1 deletion(-)
 create mode 100644 examples/substep.js

diff --git a/demo/src/Compare.js b/demo/src/Compare.js
index e93fdfc..f4bad67 100644
--- a/demo/src/Compare.js
+++ b/demo/src/Compare.js
@@ -116,7 +116,6 @@ var compare = function(examples, isDev) {
             ticks += 1;
 
             var demoBuildInstance = demoBuild.example.instance;
-            runner.isFixed = demoBuildInstance.runner.isFixed = true;
             runner.delta = demoBuildInstance.runner.delta = 1000 / 60;
 
             window.Matter = MatterBuild;
diff --git a/examples/index.js b/examples/index.js
index 6e1a615..e146895 100644
--- a/examples/index.js
+++ b/examples/index.js
@@ -41,6 +41,7 @@ module.exports = {
     stress2: require('./stress2.js'),
     stress3: require('./stress3.js'),
     stress4: require('./stress4.js'),
+    substep: require('./substep.js'),
     svg: require('./svg.js'),
     terrain: require('./terrain.js'),
     timescale: require('./timescale.js'),
diff --git a/examples/substep.js b/examples/substep.js
new file mode 100644
index 0000000..f9ef1ee
--- /dev/null
+++ b/examples/substep.js
@@ -0,0 +1,120 @@
+var Example = Example || {};
+
+Example.substep = function() {
+    var Engine = Matter.Engine,
+        Render = Matter.Render,
+        Runner = Matter.Runner,
+        Events = Matter.Events,
+        Composite = Matter.Composite,
+        MouseConstraint = Matter.MouseConstraint,
+        Mouse = Matter.Mouse,
+        Bodies = Matter.Bodies;
+
+    // create engine
+    var engine = Engine.create(),
+        world = engine.world;
+
+    // create renderer
+    var render = Render.create({
+        element: document.body,
+        engine: engine,
+        options: {
+            width: 800,
+            height: 600,
+            wireframes: false,
+            showDebug: true,
+            background: '#000',
+            pixelRatio: 2
+        }
+    });
+
+    Render.run(render);
+
+    // create runner with higher precision timestep (requires >= v0.20.0 beta)
+    var runner = Runner.create({
+        delta: 1000 / (60 * 10), // 600Hz delta = 1.666ms = 10upf @ 60fps (10x default precision)
+        maxFrameTime: 1000 / 50 // performance budget
+    });
+
+    Runner.run(runner, engine);
+
+    // demo substepping using very thin bodies (than is typically recommended)
+    Composite.add(world, [
+        Bodies.rectangle(250, 250, 300, 1.25, {
+            frictionAir: 0, 
+            friction: 0,
+            restitution: 0.9,
+            angle: 0.5,
+            render: {
+                lineWidth: 0.5,
+                fillStyle: '#f55a3c'
+            }
+        }),
+        Bodies.circle(200, 200, 2.25, {
+            frictionAir: 0, 
+            friction: 0,
+            restitution: 0.9,
+            angle: 0.5,
+            render: {
+                fillStyle: '#fff'
+            }
+        })
+    ]);
+
+    // add bodies
+    Composite.add(world, [
+        Bodies.rectangle(400, 0, 800, 50, { isStatic: true, render: { visible: false } }),
+        Bodies.rectangle(400, 600, 800, 50, { isStatic: true, render: { visible: false } }),
+        Bodies.rectangle(800, 300, 50, 600, { isStatic: true, render: { visible: false } }),
+        Bodies.rectangle(0, 300, 50, 600, { isStatic: true, render: { visible: false } })
+    ]);
+
+    // scene animation
+    Events.on(engine, 'afterUpdate', function(event) {
+        engine.gravity.scale = 0.00035;
+        engine.gravity.x = Math.cos(engine.timing.timestamp * 0.0005);
+        engine.gravity.y = Math.sin(engine.timing.timestamp * 0.0005);
+    });
+
+    // add mouse control
+    var mouse = Mouse.create(render.canvas),
+        mouseConstraint = MouseConstraint.create(engine, {
+            mouse: mouse,
+            constraint: {
+                stiffness: 0.2,
+                render: {
+                    visible: false
+                }
+            }
+        });
+
+    Composite.add(world, mouseConstraint);
+
+    // keep the mouse in sync with rendering
+    render.mouse = mouse;
+
+    // fit the render viewport to the scene
+    Render.lookAt(render, {
+        min: { x: 0, y: 0 },
+        max: { x: 800, y: 600 }
+    });
+
+    // context for MatterTools.Demo
+    return {
+        engine: engine,
+        runner: runner,
+        render: render,
+        canvas: render.canvas,
+        stop: function() {
+            Matter.Render.stop(render);
+            Matter.Runner.stop(runner);
+        }
+    };
+};
+
+Example.substep.title = 'High Substeps (Low Delta)';
+Example.substep.for = '>=0.20.0';
+
+if (typeof module !== 'undefined') {
+    module.exports = Example.substep;
+}
\ No newline at end of file