C3 runtime SDK documentation now available

I'm about to migrate my plugin to the C3 runtime.

Now expression methods should return the value using "return" statement instead of calling ret.set_int/set_float/set_string like it was in the C2 runtime. It's cool and all but I need to support both (C2 runtime and C3 runtime) versions of the plugin and the last thing I need is having two of every expression methods that are almost identical.

I thought I could avoid having identical methods by doing both "return" and "ret_set":

Expression() 
{ 
	// code goes here ------------

	ret.set_any( result ); 
	return result;
}

Well it does work because it's actually:

Expression()
{
	//- C2-C3 COMPATIBILITY ------------------------
	var params_ = Array.from(arguments);
	var ret;
	
	if( __CONSTRUCT3_RUNTIME3__ )
		ret = {set_int(){}, set_float(){}, set_string(){}, set_any(){}};
	else
	{
		ret = params_[0];
	
		for( var i=0; i<params_.length-1; i++ ) 
		params_[i] = params_[i+1];
	
		params_.pop();
	}
	//----------------------------------------------

	// runtime-independent code goes here ----------

	ret.set_any( result );
	return result;
}

Ashley

Why do you need them?

I want to port, or at least, make a basic preloader addon. I really need it for my project. I need those references to stabilize the preload and also to integrate the Construct 3 Loading. I hope you understand.

Why do you need them for a preloader addon? What does it do and why can't you do it without these? In particular requiring the FPS for this seems particularly weird.

Given we are obligated to permanently support all APIs we document with backwards-compatibility forever, I'd prefer to keep the SDK to the essential minimum.

scirra.com/store/construct2-plugins/mmpreloader-layout-preloader-3620

TobyR made some preloader addon that a lot of us agreed useful on Construct 2. To make it stable, taking FPS into account is important and the loading progress to integrate the Construct Loader Layout loading progress with the preloader layout to extend the Layout-by-Layout loading.

I actually asked this from you guys but you guys seem to have your hands full at the moment with the c3runtime and I don't want to disturb that. I only ask this so I can finally port to the c3runtime. Thank You.

Ashley

That's the wrong solution, and uses an extremely coarse measurement anyway. You probably should use something like requestIdleCallback instead.

Okay. I'll look that up.

Besides in the C3 runtime layout loading is now asynchronous so may not jank the game any more while loading. Also the whole idea of preloading an entire other layout will spike the memory usage high, significantly increasing the risk of out-of-memory crashes... it kind of defeats the point of the layout-by-layout memory management that aims to keep peak memory usage low.

Well, I'm not sure about that. But I surely haven't encountered that in c2runtime on Construct 3 at least.

Although, aside from the conventional usage of that addon, there is an exclusive use for that addon that the normal layout-by-layout loading can't do.

Imagine having 100 Spriter Character objects / 100 Sprite objects.

You have to preload only 10 of those characters per game. As you only use 10 Players per battle match.

You can't do that with normal layout-by-layout loading as you will have to load image memory that isn't even used.

With this, it ensures that images that are only needed are the ones only loaded.

Plus, you can add custom initializations per layout.

I'm not sure why this needs to have anything to do with loadingprogress either - why not just give the plugin its own expression? The more you hack in to the runtime code, the more brittle it is in the face of future changes. The best architecture is to keep as much code as possible entirely independent of the runtime.

It needs to. For example, you are on the loader layout. Before going to the main layout, you need to preload the main layout to only load the images needed and also for some custom initializations. But, you need to wait for the Construct Engine to load first or at least finish.

I hope that explains it all.

Ashley

What is the bare minimum needed to convert a C2 runtime plugin to a C3 runtime plugin? I tried looking through the plugin examples and the SDK docs, but I want to be sure I'm understanding this correctly.

From what I can tell, the following is needed:

ACES

• All ACES moved from plugin.js to their respective files
• ACES work slightly differently now and need to use return instead of SetRet

Plugin

• Boilerplate constructor code and such under plugin class such as cr.plugins_.MyCompany_MyPlugin = function(runtime) gets moved to plugin.js and adapted to the new format

Type

• Code for pluginProto.Type needs to be moved to type.js and boilerplate code like pluginProto.Type = function(plugin) adapted to the new format

Instance

• Anything that was previously instanceProto is now moved to instance.js.
• Loading resources and drawing work very differently and require adaption.
• As in the other sections, boilerplate code, constructors, etc need to be adapted.

Aside from small changes like properties being passed to constructor, as opposed to being accessed via this/

Is there anything I got wrong, or I'm missing? Also, the meat of the plugin and js methods should all function the same otherwise, or are there any additional requirements or restrictions for general code?