Add "Conveyor Belt" scene.

Author: MelvMay-Unity

LowLevel/Sandbox/Assets/Sandbox.unity

@@ -400,6 +400,10 @@ MonoBehaviour:
     Category: Shapes
     Description: Demonstrates how multiple shapes on a single body produce a compound
       shape and how to mitigate overlaps.
+  - ScenePath: Assets/Scenes/Shapes/ConveyorBelt/ConveyorBelt.unity
+    Name: Conveyor Belt
+    Category: Shapes
+    Description: Demonstrates the use of the Tangent Speed surface material property.
   - ScenePath: Assets/Scenes/Shapes/EllipsePolygons/EllipsePolygons.unity
     Name: Ellipse Polygons
     Category: Shapes

LowLevel/Sandbox/Assets/Scenes/Shapes/ConveyorBelt.meta

@@ -0,0 +1,155 @@
+using Unity.Collections;
+using UnityEngine;
+using UnityEngine.LowLevelPhysics2D;
+using UnityEngine.UIElements;
+
+public class ConveyorBelt : MonoBehaviour
+{
+    private SandboxManager m_SandboxManager;
+    private SceneManifest m_SceneManifest;
+    private UIDocument m_UIDocument;
+    private CameraManipulator m_CameraManipulator;
+
+    private PhysicsWorld m_PhysicsWorld;
+    
+    private Button m_SpawnButton;
+    private PhysicsBody m_ConveyorBeltBody;
+    private PhysicsShape m_ConveyorBeltShape;
+    
+    private float m_ConveyorSpeed;
+    private float m_ConveyorAngle;
+    
+    private void OnEnable()
+    {
+        m_SandboxManager = FindFirstObjectByType<SandboxManager>();
+        m_SceneManifest = FindFirstObjectByType<SceneManifest>();
+        m_UIDocument = GetComponent<UIDocument>();
+
+        m_CameraManipulator = FindFirstObjectByType<CameraManipulator>();
+        m_CameraManipulator.CameraSize = 12;
+        m_CameraManipulator.CameraPosition = new Vector2(0f, 7f);
+
+        // Set up the scene reset action.
+        m_SandboxManager.SceneResetAction = SetupScene;
+
+        // Set Overrides.
+        m_SandboxManager.SetOverrideColorShapeState(false);
+
+        m_PhysicsWorld = PhysicsWorld.defaultWorld;
+
+        m_ConveyorSpeed = 20f;
+        m_ConveyorAngle = 0f;
+        
+        SetupOptions();
+
+        SetupScene();
+    }
+
+    private void OnDisable()
+    {
+	    // Reset overrides.
+	    m_SandboxManager.ResetOverrideColorShapeState();        
+    }
+
+    private void SetupOptions()
+    {
+        var root = m_UIDocument.rootVisualElement;
+
+        {
+            // Menu Region (for camera manipulator).
+            var menuRegion = root.Q<VisualElement>("menu-region");
+            menuRegion.RegisterCallback<PointerEnterEvent>(_ => ++m_CameraManipulator.OverlapUI);
+            menuRegion.RegisterCallback<PointerLeaveEvent>(_ => --m_CameraManipulator.OverlapUI);
+
+            // Conveyor Speed.
+            var conveyorSpeed = root.Q<Slider>("conveyor-speed");
+            conveyorSpeed.value = m_ConveyorSpeed;
+            conveyorSpeed.RegisterValueChangedCallback(evt =>
+            {
+	            m_ConveyorSpeed = evt.newValue;
+	            
+	            // Update the tangent speed.
+	            var surfaceMaterial = m_ConveyorBeltShape.surfaceMaterial;
+				surfaceMaterial.tangentSpeed = m_ConveyorSpeed;
+	            m_ConveyorBeltShape.surfaceMaterial = surfaceMaterial;
+            });
+
+            // Conveyor Angle.
+            var conveyorAngle = root.Q<Slider>("conveyor-angle");
+            conveyorAngle.value = m_ConveyorAngle;
+            conveyorAngle.RegisterValueChangedCallback(evt =>
+            {
+	            m_ConveyorAngle = evt.newValue;
+	            
+	            // Update the conveyor angle.
+	            m_ConveyorBeltBody.rotation = new PhysicsRotate(PhysicsMath.ToRadians(m_ConveyorAngle));
+            });
+            
+            // Spawn.
+            m_SpawnButton = root.Q<Button>("spawn");
+            m_SpawnButton.clicked += () => Spawn(10);
+            
+            // Reset Scene.
+            var resetScene = root.Q<Button>("reset-scene");
+            resetScene.clicked += SetupScene;
+
+            // Fetch the scene description.
+            var sceneDescription = root.Q<Label>("scene-description");
+            sceneDescription.text = $"\"{m_SceneManifest.LoadedSceneName}\"\n{m_SceneManifest.LoadedSceneDescription}";
+        }
+    }
+
+    private void SetupScene()
+    {
+        // Reset the scene state.
+        m_SandboxManager.ResetSceneState();
+
+        var bodies = m_SandboxManager.Bodies;
+
+        // Ground.
+        {
+            var body = m_PhysicsWorld.CreateBody();
+            bodies.Add(body);
+            using var vertices = new NativeList<Vector2>(Allocator.Temp)
+            {
+	            new(-20f, 0f),
+	            new(-20f, 23f),
+	            new(20f, 23f),
+	            new(20f, 0f)
+            };
+            body.CreateChain(new ChainGeometry(vertices.AsArray()), PhysicsChainDefinition.defaultDefinition);
+        }
+        
+		// Platform.
+		{
+			m_ConveyorBeltBody = m_PhysicsWorld.CreateBody(new PhysicsBodyDefinition { position = Vector2.up * 8f });
+			bodies.Add(m_ConveyorBeltBody);
+
+			var geometry = PolygonGeometry.CreateBox(new Vector2(20f, 0.5f), 0.25f);
+			var shapeDef = new PhysicsShapeDefinition { surfaceMaterial = new PhysicsShape.SurfaceMaterial { friction = 0.8f, tangentSpeed = 2f } };
+			m_ConveyorBeltShape = m_ConveyorBeltBody.CreateShape(geometry, shapeDef);
+		}
+		
+		// Boxes.
+		{
+			Spawn(10);
+		}
+    }
+
+    private void Spawn(int spawnCount)
+    {
+	    var bodies = m_SandboxManager.Bodies;
+	    ref var random = ref m_SandboxManager.Random;
+
+	    for (var n = 0; n < spawnCount; ++n)
+	    {
+		    var spawnPosition = new Vector2(random.NextFloat(-5f, 5f), random.NextFloat(9f, 20f));
+		    var scale = random.NextFloat(0.05f, 1f);
+		    var radius = random.NextFloat(0f, 0.2f);
+		    
+		    var body = m_PhysicsWorld.CreateBody(new PhysicsBodyDefinition { bodyType = RigidbodyType2D.Dynamic, position = spawnPosition });
+		    bodies.Add(body);
+		    body.CreateShape(PolygonGeometry.CreateBox(Vector2.one * scale, radius));
+	    }
+    }
+}