Entity API

Entity (abstract)
  ├── Mob
  │     ├── Player
  │     │     ├── LocalPlayer
  │     │     └── MultiplayerLocalPlayer
  │     ├── Monster
  │     ├── Animal
  │     └── WaterAnimal
  ├── ItemEntity
  ├── PrimedTnt
  ├── FallingTile
  ├── Boat
  ├── Minecart
  ├── Arrow
  └── ExperienceOrb

static const short TOTAL_AIR_SUPPLY = 300;  // 20 * 15 seconds

int entityId;                    // Unique entity ID

Level *level;                    // World containing this entity

// Position
double x, y, z;                  // Current position
double xo, yo, zo;               // Previous tick position
double xd, yd, zd;               // Velocity/motion

// Rotation
float yRot, xRot;                // Current rotation (yaw, pitch)
float yRotO, xRotO;              // Previous tick rotation

// Bounding box
AABB *bb;                        // Collision bounding box
float bbWidth, bbHeight;         // Bounding box dimensions

// State flags
bool onGround;                   // Is entity on ground?
bool removed;                    // Is entity marked for removal?
bool inChunk;                    // Is entity in a chunk?
bool noPhysics;                  // Disable physics?

// Collision state
bool horizontalCollision;        // Hit wall this tick?
bool verticalCollision;          // Hit floor/ceiling this tick?
bool collision;                  // Any collision this tick?

// Movement
float walkDist, walkDistO;       // Walk animation distance
float fallDistance;              // Distance fallen

// Fire & damage
int flameTime;                   // Ticks on fire
int invulnerableTime;            // Ticks of invulnerability

// Riding
shared_ptr<Entity> riding;       // Entity being ridden
weak_ptr<Entity> rider;          // Entity riding this

// Misc
int tickCount;                   // Age in ticks
bool slide;                      // Slippery movement?
float heightOffset;              // Render Y offset

enum EEntityDamageType {
    eEntityDamageType_Entity,      // Attacked by entity
    eEntityDamageType_Fall,        // Fall damage
    eEntityDamageType_Fire,        // Fire/lava surface
    eEntityDamageType_Lava,        // Inside lava
    eEntityDamageType_Water,       // Drowning
    eEntityDamageType_Suffocate,   // Inside block
    eEntityDamageType_OutOfWorld,  // Void damage
    eEntityDamageType_Cactus       // Cactus contact
};

// Spawn an item at position
auto itemEntity = make_shared<ItemEntity>(level, x, y, z, itemStack);
level->addEntity(itemEntity);

// Spawn with velocity
itemEntity->xd = 0.1;
itemEntity->yd = 0.2;
itemEntity->zd = 0.0;

// Move entity with collision
entity->move(entity->xd, entity->yd, entity->zd);

if (entity->horizontalCollision) {
    // Hit a wall
    entity->xd = 0;
    entity->zd = 0;
}

if (entity->onGround) {
    // On ground - apply friction
    entity->xd *= 0.91;
    entity->zd *= 0.91;
}

// Find nearest player
shared_ptr<Player> nearest = nullptr;
double minDist = 16.0 * 16.0;  // Squared distance

for (auto& player : level->players) {
    double dist = entity->distanceToSqr(player);
    if (dist < minDist) {
        minDist = dist;
        nearest = player;
    }
}

// Fast type check
if (entity->GetType() == eTYPE_PLAYER) {
    auto player = dynamic_pointer_cast<Player>(entity);
    // Do player-specific logic
}

// Alternative with dynamic_cast
auto player = dynamic_pointer_cast<Player>(entity);
if (player) {
    // It's a player
}