hasVelocity is now false if the entity just has gravity (#975)

src/main/java/net/minestom/server/entity/Entity.java

@@ -909,10 +909,16 @@ public class Entity implements Viewable, Tickable, Schedulable, Snapshotable, Ev
     /**
      * Gets if the entity currently has a velocity applied.
      *
-     * @return true if velocity is not set to 0
+     * @return true if the entity is moving
      */
     public boolean hasVelocity() {
-        return !velocity.isZero();
+        if (isOnGround()) {
+            // if the entity is on the ground and only "moves" downwards, it does not have a velocity.
+            return Double.compare(velocity.x(), 0) != 0 || Double.compare(velocity.z(), 0) != 0 || velocity.y() > 0;
+        } else {
+            // The entity does not have velocity if the velocity is zero
+            return !velocity.isZero();
+        }
     }
 
     /**

src/test/java/net/minestom/server/entity/EntityVelocityIntegrationTest.java

@@ -8,8 +8,9 @@ import net.minestom.server.instance.Instance;
 import net.minestom.server.utils.chunk.ChunkUtils;
 import org.junit.jupiter.api.Test;
 
-import static org.junit.jupiter.api.Assertions.assertEquals;
-import static org.junit.jupiter.api.Assertions.assertTrue;
+import java.time.Duration;
+
+import static org.junit.jupiter.api.Assertions.*;
 
 @EnvTest
 public class EntityVelocityIntegrationTest {
@@ -79,6 +80,8 @@ public class EntityVelocityIntegrationTest {
         entity.takeKnockback(0.4f, 0, -1);
         entity.takeKnockback(0.5f, 0, -1);
 
+        assertTrue(entity.hasVelocity());
+
         testMovement(env, entity, new Vec[] {
                 new Vec(0.0, 40.0, 0.0),
                 new Vec(0.0, 40.4, 0.7000000029802322),
@@ -102,6 +105,29 @@ public class EntityVelocityIntegrationTest {
         });
     }
 
+    @Test
+    public void testHasVelocity(Env env) {
+        var instance = env.createFlatInstance();
+        loadChunks(instance);
+
+        var entity = new Entity(EntityType.ZOMBIE);
+        // Should  be false because the new entity should have no velocity
+        assertFalse(entity.hasVelocity());
+
+        entity.setInstance(instance, new Pos(0, 41, 0)).join();
+
+        env.tick();
+
+        // Should be true: The entity is currently falling (in the air), so it does have a velocity.
+        // Only entities on the ground should ignore the default velocity.
+        assertTrue(entity.hasVelocity());
+
+        env.tick();
+
+        // Now that the entity is on the ground, it should no longer have a velocity.
+        assertFalse(entity.hasVelocity());
+    }
+
     private void testMovement(Env env, Entity entity, Vec[] sample) {
         final double epsilon = 0.003;
         for (Vec vec : sample) {