Documented slow-mo timestepping keybind and pulled it into the demo harness. LockMouse moved to the first control slot for visibility.

Author: RossNordby

Demos/Controls.cs

@@ -220,13 +220,14 @@ public struct Controls
         public float CameraMoveSpeed;
         public float CameraFastMoveSpeed;
 
+        public HoldableBind SlowTimesteps;
         public InstantBind LockMouse;
         public InstantBind Exit;
         public InstantBind ShowConstraints;
         public InstantBind ShowContacts;
         public InstantBind ShowBoundingBoxes;
         public InstantBind ChangeTimingDisplayMode;
-        public HoldableBind ChangeDemo;
+        public InstantBind ChangeDemo;
         public InstantBind ShowControls;
 
         public static Controls Default
@@ -247,6 +248,7 @@ public static Controls Default
                     CameraSlowMoveSpeed = 0.5f,
                     CameraMoveSpeed = 5,
                     CameraFastMoveSpeed = 50,
+                    SlowTimesteps = MouseButton.Middle,
 
                     LockMouse = Key.Tab,
                     Exit = Key.Escape,

Demos/Demo.cs

@@ -35,24 +35,13 @@ protected Demo()
         }
 
         public abstract void Initialize(Camera camera);
-
-        int frameCount = 0;
+        
         public virtual void Update(Input input, float dt)
         {
-            ++frameCount;
-            //If we're running headless, there is no input.
-            if (input != null && input.IsDown(OpenTK.Input.MouseButton.Middle))
-            {
-                if (frameCount % 20 == 0)
-                    Simulation.Timestep(1 / 60f, ThreadDispatcher);
-            }
-            else
-            {
-                //TODO: While for the sake of the demos, using one update per render is probably the easiest/best choice,
-                //we can't assume that every monitor has a 60hz refresh rate. One simple option here is to just measure the primary display's refresh rate ahead of time
-                //and use that as the simulation timestep duration. Different displays would affect the simulation, but it wouldn't be too bad, and it would be locally consistent.
-                Simulation.Timestep(1 / 60f, ThreadDispatcher);
-            }
+            //TODO: While for the sake of the demos, using one update per render is probably the easiest/best choice,
+            //we can't assume that every monitor has a 60hz refresh rate. One simple option here is to just measure the primary display's refresh rate ahead of time
+            //and use that as the simulation timestep duration. Different displays would affect the simulation, but it wouldn't be too bad, and it would be locally consistent.
+            Simulation.Timestep(1 / 60f, ThreadDispatcher);
         }
 
         public virtual void Render(Renderer renderer, TextBuilder text, Font font)

Demos/DemoHarness.cs

@@ -20,6 +20,7 @@ public class DemoHarness : IDisposable
         bool showConstraints = true;
         bool showContacts;
         bool showBoundingBoxes;
+        int frameCount;
 
         enum TimingDisplayMode
         {
@@ -259,7 +260,11 @@ public void Update(float dt)
             {
                 input.MouseLocked = false;
             }
-            demo.Update(input, dt);
+            ++frameCount;
+            if (!controls.SlowTimesteps.IsDown(input) || frameCount % 20 == 0)
+            {
+                demo.Update(input, dt);
+            }
             timeSamples.RecordFrame(demo.Simulation);
         }
 
@@ -279,7 +284,7 @@ public void Render(Renderer renderer)
             if (showControls)
             {
                 var penPosition = new Vector2(window.Resolution.X - textHeight * 6 - 25, window.Resolution.Y - 25);
-                penPosition.Y -= 16 * lineSpacing;
+                penPosition.Y -= 17 * lineSpacing;
                 uiText.Clear().Append("Controls: ");
                 var headerHeight = textHeight * 1.2f;
                 renderer.TextBatcher.Write(uiText, penPosition - new Vector2(0.5f * GlyphBatch.MeasureLength(uiText, font, headerHeight), 0), headerHeight, textColor, font);
@@ -300,6 +305,7 @@ void WriteName(string controlName, string control)
                 }
 
                 //Conveniently, enum strings are cached. Every (Key).ToString() returns the same reference for the same key, so no garbage worries.
+                WriteName(nameof(controls.LockMouse), controls.LockMouse.ToString());
                 WriteName(nameof(controls.MoveForward), controls.MoveForward.ToString());
                 WriteName(nameof(controls.MoveBackward), controls.MoveBackward.ToString());
                 WriteName(nameof(controls.MoveLeft), controls.MoveLeft.ToString());
@@ -308,7 +314,7 @@ void WriteName(string controlName, string control)
                 WriteName(nameof(controls.MoveDown), controls.MoveDown.ToString());
                 WriteName(nameof(controls.MoveSlower), controls.MoveSlower.ToString());
                 WriteName(nameof(controls.MoveFaster), controls.MoveFaster.ToString());
-                WriteName(nameof(controls.LockMouse), controls.LockMouse.ToString());
+                WriteName(nameof(controls.SlowTimesteps), controls.SlowTimesteps.ToString());
                 WriteName(nameof(controls.Exit), controls.Exit.ToString());
                 WriteName(nameof(controls.ShowConstraints), controls.ShowConstraints.ToString());
                 WriteName(nameof(controls.ShowContacts), controls.ShowContacts.ToString());