feat : field with view component

Author: elebras1

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

@@ -42,10 +42,16 @@ public static void main(String[] args) {
                 System.out.println("--- Benchmark 1: each() + entity.get(Component.class) ---");
                 runBenchmark("each+get", () -> benchmarkEachGet(world, query));
 
-                System.out.println("--- Benchmark 2: iter() + Field<T>.get(i) ---");
-                runBenchmark("iter+Field", () -> benchmarkIterField(query));
+                System.out.println("--- Benchmark 2: each() + entity.getMutView(Component.class) ---");
+                runBenchmark("each+getMutView", () -> benchmarkEachGetMutView(world, query));
 
-                System.out.println("--- Benchmark 3: iter() + fieldFloat() (native) ---");
+                System.out.println("--- Benchmark 3: iter() + Field<T>.get(i) ---");
+                runBenchmark("iter+Field+get", () -> benchmarkIterFieldGet(query));
+
+                System.out.println("--- Benchmark 4: iter() + Field<T>.getMutView(i) ---");
+                runBenchmark("iter+Field+getMutView", () -> benchmarkIterFieldGetMutView(query));
+
+                System.out.println("--- Benchmark 5: iter() + fieldFloat() (native) ---");
                 runBenchmark("iter+native", () -> benchmarkIterNative(query));
 
                 System.out.println();
@@ -67,7 +73,20 @@ private static float benchmarkEachGet(World world, Query query) {
         return sum[0];
     }
 
-    private static float benchmarkIterField(Query query) {
+    private static float benchmarkEachGetMutView(World world, Query query) {
+        final float[] sum = {0.0f};
+
+        query.each(entityId -> {
+            Entity entity = world.obtainEntity(entityId);
+            PositionView pos = entity.getMutView(Position.class);
+            VelocityView vel = entity.getMutView(Velocity.class);
+            sum[0] += pos.x() + pos.y() + vel.dx() + vel.dy();
+        });
+
+        return sum[0];
+    }
+
+    private static float benchmarkIterFieldGet(Query query) {
         final float[] sum = {0.0f};
 
         query.iter(iter -> {
@@ -84,6 +103,23 @@ private static float benchmarkIterField(Query query) {
         return sum[0];
     }
 
+    private static float benchmarkIterFieldGetMutView(Query query) {
+        final float[] sum = {0.0f};
+
+        query.iter(iter -> {
+            Field<Position> positions = iter.field(Position.class, 0);
+            Field<Velocity> velocities = iter.field(Velocity.class, 1);
+
+            for (int i = 0; i < iter.count(); i++) {
+                PositionView pos = positions.getMutView(i);
+                VelocityView vel = velocities.getMutView(i);
+                sum[0] += pos.x() + pos.y() + vel.dx() + vel.dy();
+            }
+        });
+
+        return sum[0];
+    }
+
     private static float benchmarkIterNative(Query query) {
         final float[] sum = {0.0f};
 

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

@@ -200,7 +200,7 @@ public <T> T get(Class<T> componentClass, long target) {
     }
 
     @SuppressWarnings("unchecked")
-    public <T> T getMutView(Class<?> componentClass) {
+    public <T extends ComponentView> T getMutView(Class<?> componentClass) {
         ComponentView view = FlecsContext.CURRENT_CACHE.get().get(componentClass);
 
         long componentId = this.world.componentRegistry().getComponentId(componentClass);

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

@@ -7,11 +7,13 @@ public class Field<T> {
     private final MemorySegment memorySegment;
     private final int count;
     private final Component<T> component;
+    private final ComponentView componentView;
 
     Field(MemorySegment memorySegment, int count, World world, Class<T> componentClass) {
         this.memorySegment = memorySegment;
         this.count = count;
         this.component = world.componentRegistry().getComponent(componentClass);
+        this.componentView = FlecsContext.CURRENT_CACHE.get().get(componentClass);
     }
 
     public boolean isSet() {
@@ -36,6 +38,22 @@ public T get(int i) {
         return this.component.read(elementSegment);
     }
 
+    @SuppressWarnings("unchecked")
+    public <V extends ComponentView> V getMutView(int i) {
+        if (!this.isSet()) {
+            throw new IllegalStateException("Field is not set.");
+        }
+        if (i < 0 || i >= this.count) {
+            throw new IndexOutOfBoundsException("Index " + i + " out of bounds for count " + this.count);
+        }
+
+        long elementOffset = i * this.component.size();
+        MemorySegment elementSegment = this.memorySegment.asSlice(elementOffset, this.component.size());
+        this.componentView.setMemorySegment(elementSegment);
+
+        return (V) this.componentView;
+    }
+
     public void set(int i, T componentData) {
         if (!this.isSet()) {
             throw new IllegalStateException("Field is not set.");