API: Canvas (r2)

This API is for Worlds that use a canvas to do their own 2D or WebGL rendering. It does not come with a graphics library or with any Ancient Brain framework. Anything written in JS for a canvas should run using this API without change.

This API has the following features:

• No graphics library.
• No Ancient Brain framework.
• The author has to do create canvas themselves and do their own 2D or WebGL rendering.
• See 2D rendering documentation and WebGL rendering documentation.
• Includes jQuery 3.6.0.
• Loads up minimal CSS that should not conflict with user CSS.
• The screenshot assumes a canvas exists and takes a screenshot of that.

• Run header on RHS. Many JS worlds use fixed small dimension canvas, which will go in top LHS. So this API puts run header on RHS.
• If World uses Minds, World author must call the Mind themselves:

   AB.mind.getAction ( state );  

---

Templates

• World with no Mind

• World with Mind
• Mind

ABWorld

This API defines a global variable called "ABWorld" with not much in it:

 

 ABWorld;                 // instance of class ABWorldClass  
 

 ABWorld.canvas;          // a variable to point to the canvas   		
 
 // When making a screenshot, Ancient Brain will search for the canvas.
 // If it cannot find the canvas, set this variable to point to it.
 
 
 ABWorld.fullwidth();     // return full width of window on desktop / screen on mobile 
 ABWorld.fullheight();    // return full height of window on desktop / screen on mobile

getContext: preserveDrawingBuffer

The following is important if you are creating a "webgl" context.

Ancient Brain needs runs to be able to generate a screenshot.
If you are doing WebGL rendering (context "webgl"), you need in canvas.getContext to set "preserveDrawingBuffer" = true.
You need something like:

 
 ctx = canvas.getContext ( "webgl", { preserveDrawingBuffer: true } );	

You might set it to true for "generate image" runs and false for normal runs:

 
 if ( AB.isScreenshotRun() )
	 ctx = canvas.getContext ( "webgl", { preserveDrawingBuffer: true } );	
 else                       
	 ctx = canvas.getContext ( "webgl", { preserveDrawingBuffer: false } );	

Examples

Examples of Worlds that use this API: