Fix onGround field and gravityTickCount

src/main/java/net/minestom/server/collision/CollisionUtils.java

@@ -26,7 +26,10 @@ public class CollisionUtils {
      * @param velocityOut   the Vector object in which the new velocity will be saved
      * @return whether this entity is on the ground
      */
-    public static boolean handlePhysics(Entity entity, Vector deltaPosition, Position positionOut, Vector velocityOut) {
+    public static boolean handlePhysics(@NotNull Entity entity,
+                                        @NotNull Vector deltaPosition,
+                                        @NotNull Position positionOut,
+                                        @NotNull Vector velocityOut) {
         // TODO handle collisions with nearby entities (should it be done here?)
         final Instance instance = entity.getInstance();
         final Position currentPosition = entity.getPosition();
@@ -75,7 +78,7 @@ public class CollisionUtils {
      * @param stepAmount    how much to step in the direction (in blocks)
      * @param positionOut   the vector in which to store the new position
      * @param corners       the corners to check against
-     * @return true iif a collision has been found
+     * @return true if a collision has been found
      */
     private static boolean stepAxis(Instance instance, Vector startPosition, Vector axis, float stepAmount, Vector positionOut, Vector... corners) {
         positionOut.copy(startPosition);

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

@@ -453,6 +453,13 @@ public abstract class Entity implements Viewable, EventHandler, DataContainer, P
         // Entity tick
         {
 
+            // Cache the number of "gravity tick"
+            if (!onGround) {
+                gravityTickCount++;
+            } else {
+                gravityTickCount = 0;
+            }
+
             // Velocity
             boolean applyVelocity;
             // Non-player entities with either velocity or gravity enabled
@@ -467,32 +474,19 @@ public abstract class Entity implements Viewable, EventHandler, DataContainer, P
                 final float newZ = position.getZ() + velocity.getZ() / tps;
                 Position newPosition = new Position(newX, newY, newZ);
 
-                // Gravity
-                {
-                    // Cache the number of "gravity tick"
-                    if (!onGround) {
-                        gravityTickCount++;
-                    } else {
-                        gravityTickCount = 0;
-                    }
-
-                    // Compute the gravity change (drag per tick + acceleration)
-                    final float gravityY = Math.min(
-                            gravityDragPerTick + (gravityAcceleration * (float) gravityTickCount),
-                            gravityTerminalVelocity);
-
-                    // Change velocity to apply gravity
-                    if (!noGravity) {
-                        velocity.setY(velocity.getY() - gravityY);
-                    }
-                }
-
                 Vector newVelocityOut = new Vector();
+
+                // Gravity force
+                final float gravityY = !noGravity ? Math.min(
+                        gravityDragPerTick + (gravityAcceleration * (float) gravityTickCount),
+                        gravityTerminalVelocity) : 0f;
+
                 final Vector deltaPos = new Vector(
                         getVelocity().getX() / tps,
-                        getVelocity().getY() / tps,
+                        (getVelocity().getY() - gravityY) / tps,
                         getVelocity().getZ() / tps
                 );
+
                 this.onGround = CollisionUtils.handlePhysics(this, deltaPos, newPosition, newVelocityOut);
 
                 // Stop here if the position is the same
@@ -535,7 +529,7 @@ public abstract class Entity implements Viewable, EventHandler, DataContainer, P
 
                         // Stop player velocity
                         if (PlayerUtils.isNettyClient(this)) {
-                            velocity.zero();
+                            this.velocity.zero();
                         }
                     } else {
                         drag = 0.98f; // air drag

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

@@ -130,7 +130,6 @@ public class Player extends LivingEntity implements CommandSender {
     protected final Set<Chunk> viewableChunks = new CopyOnWriteArraySet<>();
     private final AtomicInteger teleportId = new AtomicInteger();
 
-    protected boolean onGround;
     private final Queue<ClientPlayPacket> packets = Queues.newConcurrentLinkedQueue();
     private final boolean levelFlat;
     private final PlayerSettings settings;

src/main/java/net/minestom/server/listener/PlayerPositionListener.java

@@ -52,7 +52,6 @@ public class PlayerPositionListener {
 
     private static void processMovement(@NotNull Player player, float x, float y, float z,
                                         float yaw, float pitch, boolean onGround) {
-
         final Instance instance = player.getInstance();
 
         // Prevent moving before the player spawned, probably a modified client (or high latency?)

src/main/java/net/minestom/server/utils/Vector.java

@@ -21,13 +21,15 @@ public class Vector implements PublicCloneable<Vector> {
         this.z = z;
     }
 
-    public Vector add(Vector vec) {
+    @NotNull
+    public Vector add(@NotNull Vector vec) {
         x += vec.x;
         y += vec.y;
         z += vec.z;
         return this;
     }
 
+    @NotNull
     public Vector add(float x, float y, float z) {
         this.x += x;
         this.y += y;
@@ -41,13 +43,15 @@ public class Vector implements PublicCloneable<Vector> {
      * @param vec The other vector
      * @return the same vector
      */
-    public Vector subtract(Vector vec) {
+    @NotNull
+    public Vector subtract(@NotNull Vector vec) {
         x -= vec.x;
         y -= vec.y;
         z -= vec.z;
         return this;
     }
 
+    @NotNull
     public Vector subtract(float x, float y, float z) {
         this.x -= x;
         this.y -= y;
@@ -61,7 +65,8 @@ public class Vector implements PublicCloneable<Vector> {
      * @param vec The other vector
      * @return the same vector
      */
-    public Vector multiply(Vector vec) {
+    @NotNull
+    public Vector multiply(@NotNull Vector vec) {
         x *= vec.x;
         y *= vec.y;
         z *= vec.z;
@@ -74,7 +79,8 @@ public class Vector implements PublicCloneable<Vector> {
      * @param vec The other vector
      * @return the same vector
      */
-    public Vector divide(Vector vec) {
+    @NotNull
+    public Vector divide(@NotNull Vector vec) {
         x /= vec.x;
         y /= vec.y;
         z /= vec.z;
@@ -87,7 +93,8 @@ public class Vector implements PublicCloneable<Vector> {
      * @param vec The other vector
      * @return the same vector
      */
-    public Vector copy(Vector vec) {
+    @NotNull
+    public Vector copy(@NotNull Vector vec) {
         x = vec.x;
         y = vec.y;
         z = vec.z;
@@ -128,7 +135,7 @@ public class Vector implements PublicCloneable<Vector> {
      * @param o The other vector
      * @return the distance
      */
-    public double distance(Vector o) {
+    public double distance(@NotNull Vector o) {
         return Math.sqrt(MathUtils.square(x - o.x) + MathUtils.square(y - o.y) + MathUtils.square(z - o.z));
     }
 
@@ -138,7 +145,7 @@ public class Vector implements PublicCloneable<Vector> {
      * @param o The other vector
      * @return the squared distance
      */
-    public double distanceSquared(Vector o) {
+    public double distanceSquared(@NotNull Vector o) {
         return MathUtils.square(x - o.x) + MathUtils.square(y - o.y) + MathUtils.square(z - o.z);
     }
 
@@ -149,6 +156,7 @@ public class Vector implements PublicCloneable<Vector> {
      * @param m The factor
      * @return the same vector
      */
+    @NotNull
     public Vector multiply(int m) {
         x *= m;
         y *= m;
@@ -163,6 +171,7 @@ public class Vector implements PublicCloneable<Vector> {
      * @param m The factor
      * @return the same vector
      */
+    @NotNull
     public Vector multiply(double m) {
         x *= m;
         y *= m;
@@ -177,6 +186,7 @@ public class Vector implements PublicCloneable<Vector> {
      * @param m The factor
      * @return the same vector
      */
+    @NotNull
     public Vector multiply(float m) {
         x *= m;
         y *= m;
@@ -204,6 +214,7 @@ public class Vector implements PublicCloneable<Vector> {
      *
      * @return the same vector
      */
+    @NotNull
     public Vector zero() {
         x = 0;
         y = 0;
@@ -295,7 +306,17 @@ public class Vector implements PublicCloneable<Vector> {
      *
      * @return this vector as a position
      */
+    @NotNull
     public Position toPosition() {
         return new Position(x, y, z);
     }
+
+    /**
+     * Get the threshold used for equals().
+     *
+     * @return The epsilon.
+     */
+    public static double getEpsilon() {
+        return epsilon;
+    }
 }

src/test/java/demo/PlayerInit.java

@@ -8,7 +8,6 @@ import net.minestom.server.chat.ColoredText;
 import net.minestom.server.entity.*;
 import net.minestom.server.entity.damage.DamageType;
 import net.minestom.server.entity.type.monster.EntityZombie;
-import net.minestom.server.entity.type.other.EntityEndCrystal;
 import net.minestom.server.event.GlobalEventHandler;
 import net.minestom.server.event.entity.EntityAttackEvent;
 import net.minestom.server.event.entity.EntityPotionAddEvent;
@@ -192,12 +191,6 @@ public class PlayerInit {
             EntityZombie entityZombie = new EntityZombie(new Position(0, 41, 0));
             entityZombie.setInstance(player.getInstance());
             entityZombie.setPathTo(player.getPosition());
-
-            {
-                EntityEndCrystal entityEndCrystal = new EntityEndCrystal(player.getPosition());
-                entityEndCrystal.setInstance(instanceContainer);
-                entityEndCrystal.setBeamTarget(player.getPosition().toBlockPosition().add(5, 5, 0));
-            }
         });
 
         globalEventHandler.addEventCallback(PlayerDisconnectEvent.class, event -> {
@@ -223,7 +216,7 @@ public class PlayerInit {
 
         globalEventHandler.addEventCallback(PlayerSpawnEvent.class, event -> {
             final Player player = event.getPlayer();
-            player.setGameMode(GameMode.SURVIVAL);
+            player.setGameMode(GameMode.CREATIVE);
 
             PlayerInventory inventory = player.getInventory();
             ItemStack itemStack = new ItemStack(Material.STONE, (byte) 64);