feat : entity view

Author: elebras1

examples/src/main/java/com/github/elebras1/flecs/examples/ViewExample.java

@@ -1,6 +1,7 @@
 package com.github.elebras1.flecs.examples;
 
 import com.github.elebras1.flecs.Entity;
+import com.github.elebras1.flecs.EntityView;
 import com.github.elebras1.flecs.World;
 import com.github.elebras1.flecs.examples.components.*;
 import com.github.elebras1.flecs.util.FlecsConstants;
@@ -13,24 +14,27 @@ public static void main(String[] args) {
             world.component(Velocity.class);
             world.component(Inventory.class);
 
-            for (int i = 0; i < 10; i++) {
-                long entityId = world.entity("Entity_" + i);
-                Entity entity = world.obtainEntity(entityId);
-                entity.set(new Position(i * 10.0f, i * 5.0f));
-                entity.set(new Velocity(1.0f, 0.5f));
-                int[] elements = new int[10];
-                for(int j = 0; j < elements.length; j++) {
-                    elements[j] = j;
+            // obtainEntityView() requires an active scope to function properly.
+            world.scope(() -> {
+                for (int i = 0; i < 10; i++) {
+                    long entityId = world.entity("Entity_" + i);
+                    EntityView entityView = world.obtainEntityView(entityId);
+                    entityView.set(new Position(i * 10.0f, i * 5.0f));
+                    entityView.set(new Velocity(1.0f, 0.5f));
+                    int[] elements = new int[10];
+                    for(int j = 0; j < elements.length; j++) {
+                        elements[j] = j;
+                    }
+                    entityView.set(new Inventory(elements));
                 }
-                entity.set(new Inventory(elements));
-            }
+            });
 
             world.system("MovementSystem").kind(FlecsConstants.EcsOnUpdate).with(Position.class).with(Velocity.class).multiThreaded().each(entityId -> {
-                Entity entity = world.obtainEntity(entityId);
+                EntityView entityView = world.obtainEntityView(entityId);
 
-                PositionView positionView = entity.getMutView(Position.class);
-                VelocityView velocityView = entity.getMutView(Velocity.class);
-                InventoryView inventoryView = entity.getMutView(Inventory.class);
+                PositionView positionView = entityView.getMutView(Position.class);
+                VelocityView velocityView = entityView.getMutView(Velocity.class);
+                InventoryView inventoryView = entityView.getMutView(Inventory.class);
 
                 float currentX = positionView.x();
                 float currentY = positionView.y();

src/main/java/com/github/elebras1/flecs/Entity.java

@@ -9,14 +9,22 @@
 
 public class Entity {
 
-    private final World world;
-    private final long id;
+    private World world;
+    private long id;
 
     Entity(World world, long id) {
         this.world = world;
         this.id = id;
     }
 
+    protected void setWorld(World world) {
+        this.world = world;
+    }
+
+    protected void setId(long id) {
+        this.id = id;
+    }
+
     public long id() {
         return id;
     }

src/main/java/com/github/elebras1/flecs/EntityView.java

@@ -0,0 +1,8 @@
+package com.github.elebras1.flecs;
+
+public class EntityView extends Entity {
+
+    EntityView(World world, long id) {
+        super(world, id);
+    }
+}

src/main/java/com/github/elebras1/flecs/FlecsContext.java

@@ -8,9 +8,11 @@ public class FlecsContext {
 
     public static class ViewCache {
         private final Map<Class<?>, ComponentView> views;
+        private final EntityView entityView;
 
         public ViewCache() {
             this.views = new IdentityHashMap<>(8);
+            this.entityView = new EntityView(null, 0);
         }
 
         public ComponentView get(Class<?> componentClass) {
@@ -27,5 +29,9 @@ public ComponentView get(Class<?> componentClass) {
 
             return view;
         }
+
+        public EntityView getEntityView() {
+            return this.entityView;
+        }
     }
 }

src/main/java/com/github/elebras1/flecs/World.java

@@ -184,6 +184,17 @@ public Entity obtainEntity(long entityId) {
         return new Entity(this, entityId);
     }
 
+    public EntityView obtainEntityView(long entityId) {
+        if(entityId <= 0) {
+            throw new IllegalArgumentException("Invalid entity ID: " + entityId);
+        }
+
+        EntityView entityView = FlecsContext.CURRENT_CACHE.get().getEntityView();
+        entityView.setWorld(this);
+        entityView.setId(entityId);
+        return entityView;
+    }
+
     MemorySegment getComponentBuffer(long size) {
         return this.defaultBuffers.componentBuffer().ensure(size);
     }