C++ API Reference

Game

Game is the base class for your application. Override Start(), Update(), and optionally Stop(). Instantiate via the factory function CreateGame<T>() which sets up all engine internals before returning.

#include <Simple3D/Core/Game.h>

class MyGame : public Simple3D::Game {
public:
    void Start()           override;
    void Update(float dt)  override;
    void Stop()            override;  // optional
};

int main() {
    return Simple3D::CreateGame<MyGame>()->Run();
}

Lifecycle callbacks

Scene creation

Audio

Keyboard & Mouse Input

Key enum — full reference

Touch Input

Touch input is available on Android, iOS, and desktop systems with a touch screen. On desktop without a touch screen, all touch counts return 0.

int n = GetTouchCount();           // number of active touch points (0–10)

for (int i = 0; i < n; ++i) {
    Vector2 pos  = GetTouchPosition(i);   // screen pixels; (0,0) top-left
    Vector2 dlt  = GetTouchDelta(i);      // movement since last frame
    float   pres = GetTouchPressure(i);   // 0.0 (lightest) – 1.0 (hardest)
}

// Detect tap (first frame of new touch):
bool tapped = (GetTouchCount() > 0 && GetTouchDelta(0).Length() < 2.0f);

Rendering & Window

Navigation (NavMesh)

Navigation mesh baking must be called after placing all static level geometry in Start(). It is a potentially expensive one-time operation (runs on a worker thread in Urho3D, so Start() returns immediately).

Miscellaneous

Entity

Entities are created via Game::CreateEntity(name) and destroyed via Game::DestroyEntity(e). Do not delete them manually.

Entity* e = CreateEntity("MyObject");

Transform

3D Rendering

2D Rendering

Physics — 3D (Bullet)

// ── Adding physics ─────────────────────────────────────────────────
e->AddRigidBody(70.0f);                        // 70 kg dynamic body
e->AddRigidBody(0.0f);                         // 0 kg = static (immovable)

e->AddBoxCollider(Vector3(1, 2, 1));           // full-size (not half-extents)
e->AddCapsuleCollider(0.4f, 1.75f);           // radius, total height
e->AddSphereCollider(0.5f);                   // radius
e->AddMeshCollider("Models/dungeon.obj");      // triangle mesh (static only)

// ── Forces & velocity ──────────────────────────────────────────────
e->ApplyImpulse(Vector3(0, 8, 0));             // instant velocity change (jump)
e->ApplyForce(Vector3(0, 0, 20));              // continuous force (rocket)
e->SetLinearVelocity(Vector3(5, 0, 0));       // override velocity directly
Vector3 v = e->GetLinearVelocity();

// ── Ground detection ──────────────────────────────────────────────
bool grounded = e->IsOnGround();                // raycast 0.7m downward

// ── Collision filtering ────────────────────────────────────────────
e->SetCollisionLayer(1);   // bit flags — which layer this body IS on
e->SetCollisionMask(0xFF); // bit flags — which layers it COLLIDES with

Trigger volumes

// Trigger shapes
e->AddTriggerBox(Vector3(4, 3, 4));
e->AddTriggerSphere(2.5f);
e->AddTriggerCapsule(0.8f, 2.0f);

// Callbacks — 'other' is the Entity that entered / exited
e->SetOnTriggerEnter([](Entity* other) {
    // Fire on first overlapping frame.
    // 'other' pointer is guaranteed valid during this call.
});
e->SetOnTriggerExit([](Entity* other) {
    // Fire on first non-overlapping frame after overlap.
});

Full 3D physics method table

Physics — 2D (Box2D)

e->AddRigidBody2D(60.0f);            // dynamic; mass in kg
e->AddRigidBody2D(0.0f);             // static
e->AddBoxCollider2D(1.0f, 2.0f);    // width, height in world units
e->AddCircleCollider2D(0.5f);       // radius in world units

e->SetLinearVelocity2D(Vector2(5, 0));
Vector2 v = e->GetLinearVelocity2D();
e->ApplyImpulse2D(Vector2(0, 8));

bool grounded = e->IsOnGround2D();   // downward ray 0.6 m

Animation

e->AddAnimationController();
AnimationController* anim = e->GetAnimationController();
// Returns nullptr if AddAnimationController() has not been called yet.

Navigation

// First, bake nav-mesh in Start() after placing all static terrain:
BuildNavMesh(0.35f, 1.8f, 0.25f);

// Query path from enemy to a target (returns empty vector if no path):
std::vector<Vector3> path = enemy->FindPath(player);
std::vector<Vector3> path = enemy->FindPath(Vector3(10, 0, 5));

// Auto-follow: call in Update(). Recomputes path when target drifts > 1 m.
// Returns true while still moving, false when destination reached.
bool moving = enemy->MoveToward(player, 3.5f, dt);   // 3.5 m/s
bool moving = enemy->MoveToward(Vector3(10, 0, 5), 3.5f, dt);

enemy->StopMoving();   // clear cached path, zero horizontal velocity

Scripting

e->AddScript("Scripts/enemy.lua");

Each entity can have one script. The script file is loaded from the resource cache. If the file is not found, a warning is logged and no script is attached (the entity continues to work normally). The script's Start() is called on the first frame after Start() of the game has completed.

Hierarchy

Entity* child  = parent->CreateChild("Weapon");
Entity* parent = child->GetParent();   // nullptr for root entities

Child entities inherit their parent's transform (position, rotation, scale). Moving the parent moves all children. This is used for weapon attachment, character sub-parts, and complex hierarchical objects.

When the parent entity is destroyed via DestroyEntity(parent), all children are also destroyed and removed from the registry.

Camera

Camera* cam = CreateCamera();

Third-Person Follow

Orbit Mode

First-Person (FPS) Mode

Camera Collision Avoidance

cam->SetCollisionEnabled(true);

When enabled, the camera raycasts between the follow target and its intended position. If a static collision object is in the way, the camera is pulled in to avoid clipping. Only raycasts against static bodies on collision layer 2. Dynamic objects (enemies, crates) do not block the camera.

2D / Orthographic Setup

cam->Setup2D(100.0f);   // 100 pixels per world unit
// Equivalent to:
cam->SetOrthographic(true);
cam->SetOrthoSize(7.2f);   // 720 px / 100 ppu = 7.2 world units visible vertically

Split-Screen

cam1->SetViewport(0, 0.0f, 0.0f, 0.5f, 1.0f);  // index, x, y, w, h  (0–1 normalized)
cam2->SetViewport(1, 0.5f, 0.0f, 0.5f, 1.0f);

Viewport coordinates are in the range 0–1 (fraction of the window). The index parameter (0, 1, 2, …) determines render order; higher indices draw on top. All viewport cameras share the same scene.

Projection Parameters

NetworkManager

NetworkManager* net = CreateNetworkManager();

Server side

Client side

Both sides

net->SetOnMessage([](int sender, int msgId,
                    const std::vector<uint8_t>& data) {
    // sender == 0  → came from server (on client)
    // sender == N  → came from client N (on server)
    if (msgId == 100) {
        // unpack data …
    }
});

Label (UI)

Label* lbl = CreateLabel("Score: 0");

Math Types

All types are re-exported from Urho3D math as Simple3D:: aliases. They are ABI-identical — no conversion overhead when crossing the API boundary.