Cinder-Dart

This cinderblock allows you to embed the Dart virtual machine in a cinder (C++) app, providing scripting functionality in a modern web language.

Installation instructions

Clone this repo to your cinder/blocks folder and use TinderBox to create your project, selecting Cinder-Dart as a dependency.

You'll need to install the dart runtime libraries before running your app. 64-bit binaries are supplied for Mac OS X and Windows Desktop (you'll have to build for 32-bit if needed).

Get them by running the following command:

./fetch_libs.sh

In any event, or if fmy ghetto script doesn't work, ensure the dart_runtime folder layout is as such (if needed, you can manually download the lib binaries by looking at the package url output from the script):

Mac:

dart-runtime
  include
  lib
    macosx
      Debug
        libdart_runtime.a
      Release
        libdart_runtime.a
    snapshot_gen.bin

Windows:

dart-runtime
  include
  lib
    msw
      x64
        Debug
          libdart_runtime.lib
        Release
          libdart_runtime.lib
    snapshot_gen.bin

Resource files utilized by the VM:

There are a couple files that, while not technically necessary, improve usage of the Dart VM.

• cinder.dart: This file maps dart's print function back to the cinder's app::console(), and also provides you with some basic objects like Color, Vec2, and Rect. It is loaded when the Script initializes, so it is required.
• snapshot_gen.bin: this file dramatically speeds up startup time, since it provides the VM with an already serializd binary heap of an initialized Dart isolate, including all of its libraries. More info on snapshots in dart can be found here.

If you're using tinderbox, both of the files are added as resources to your app project. Use the following to tell the VM where they are:

#include "cidart/VM.h"

cidart::VM::setCinderDartScriptDataSource( app::loadResource( CIDART_RES_CINDER_DART ) );
cidart::VM::setSnapshotBinDataSource( app::loadResource( CIDART_RES_SNAPSHOT_BIN ) );

loadScript();

Alternatively, there are methods on cidart::VM to set the full paths to the resource file.

Usage

The api is a combination of the dart embedder's api and helper functions in cidart/Types.h. Refer to the samples for how to interpret Dart_Handles.

Below are a couple brief examples as an introduction.

Load a script that calls a native function

main.dart:

void customCallback( String message ) native "customCallback";

void main()
{
	customCallback( "Hey Hey" );
}

cpp:

auto opts = cidart::Script::Options().native( "customCallback",
      [this] ( Dart_NativeArguments args ) {
        string message = cidart::getArg<string>( args, 1 );
      } );

mScript = cidart::Script::create( loadAsset( "main.dart" ), opts );

Note that when using std::functions to connect native callbacks to C++, the first argument passed back in Dart_NativeArguments is the native id string (e.g. "customCallback" in above example), followed by the rest of the arguments passed from dart.

Parse fields from a dart class

(snippet taken from DartFields sample)

dart:

import 'cinder.dart';

class BreathingRect {
	Vec2	  pos = new Vec2( 50, 50 );
	Vec2	  size = new Vec2( 20, 20 );
	Color 	color = new Color( 1, 1, 1 );
	num   	speed = 1;
	num     seed = 0;
}

cpp:

BreathingRect br;
br.pos = cidart::getField<vec2>( handle, "pos" );
br.size = cidart::getField<vec2>( handle, "size" );
br.color = cidart::getField<ColorA>( handle, "color" );
br.speed = cidart::getField<float>( handle, "speed" );
br.seed = cidart::getField<float>( handle, "seed" );

See the samples folder for more detailed examples.

Credits

• The Google Dart team
• Richard Eakin ([email protected])
• http://www.libcinder.org