MushMachine/docs/framework/engine/engine.md

Engine

The Engine is the heart of the MushMachine framework. It holds the Storage of all MM::Services, update callbacks and is responsible for calling them.

Usage

Provides a forwarding header <mm/engine_fwd.hpp>.

Construction

The MM::Engine provides a Constructor which accepts a time interval, in which .fixedUpdate() is called. The Default is 1/60.

Starting

#include <mm/engine.hpp>

MM::Engine engine;

// add and enable MM::Services here

engine.run();

The MM::Engine disables all enabled MM::Services in reverse order on destruction or .cleanup().

Managing MM::Services

Adding a MM::Service

Before a MM::Service can be enabled, it needs to be added to the engine. .addService<MyService>(my, args) adds a service and forwards args to its constructor. There is currently no way of removing a MM::Service.

Getting a MM::Service

You can get a Pointer via .tryService<MyService>() and an asserted reference via .getService<MyService>(). If the MM::Service does not exist, it returns a `nullptr. "Enablement Status" makes no difference.

Provide a MM::Service (Interfaces)

.provide<MyServiceInterface, MyService>() registers MyService also as MyServiceInterface, so MyService becomes getable via MyServiceInterface. MyService needs to be added beforehand.

Enabling/Disabling a MM::Service

MM::Services can be Enabled/Disabled during .run() as a deferred operation (see .addFixedDefer(...))

• .enableService<MyService>() calles the .enable() of MyService. Also returns true on success.
• .disableService<MyService>() calles the .disable() of MyService. There are also overloads, which accept a type id.

Update / FixedUpdate

FixedUpdates are called with update interval (default 1/60, set on engine ctr), while Updates are called "as fast as possible". Since Rendering is usually done using Update and blocks on VSync, this is as fast as VSync.

Since fixedUpdate callbacks don't get a time delta, querying .getFixedDeltaTime() is mandatory.

adding Update callbacks

.addUpdate(MyFn) and .addFixedUpdate(MyFn) add MyFn as an update and fixedUpdate respectively and return a FunctionDataHandle(ptr) to remove them again.

removing Update callbacks

.removeUpdate(myHandle) and .removeFixedUpdate(myHandle) remove those callbacks again.

.run()

.run() is a blocking call, which calles .fixedUpdate() in a fixed interval with an accumulator. Inbetween those .fixedUpdate()s, .update() gets called "as fast as possible".

You don't need to call .run(), instead you can call .update() and .fixedUpdate() yourself.

.stop()

Stops the Engine... Actually quits the loop in .run().