Add a me.Path2D API for better abstraction between Canvas and WebGL

[agmcleod]

melonJS/src/video/canvas/canvas_renderer.js

Line 454 in 939428e

drawShape : function (shape) {

This method uses stroke calls. It should be an option to do stroke or fill.

[parasyte]

Reminder: We don't have fill operations in the WebGL compositor.

[agmcleod]

Oh that's a good point, hmmm.

[parasyte]

We will need an equivalent of the Canvas Path API to support all of the fill operations in WebGL. At the moment we can only fill rectangles using the quad shader.

[obiot]

moving to 3.0.0, looks like too many changes to have this ready for 2.2.0

[obiot]

looking at this old ticket, we already have some fill[Shape] function :
https://github.com/melonjs/melonJS/blob/master/src/video/canvas/canvas_renderer.js#L223

but to make it generic, i would rather keep only the generic drawShape one as the public one :
https://github.com/melonjs/melonJS/blob/master/src/video/canvas/canvas_renderer.js#L500

and then mimic the canvas API by adding a fillStyle and setStroke properties or function that can be called before and after the drawShape function

note: Flash defines a beginFill and endFill function, we could reuse the same approach and extend to stroke with beginStroke and endStroke ?
http://help.adobe.com/en_US/AS2LCR/Flash_10.0/help.html?content=00001280.html

that would give the following semantic :

renderer.beginFill(0x333333);
renderer.beginStroke(0xFFFFFF);

renderer.drawShape(myShape);

renderer.endFill(); // optional if subsequent shapes should use the same
renderer.endStroke(); // optional if subsequent shapes should use the same

[parasyte]

That Flash API doesn't feel much like Canvas. What we really need to do is polyfill the Path2D API: https://developer.mozilla.org/en-US/docs/Web/API/Path2D (and implement it directly for WebGL) as a replacement for custom stuff like drawShape.

[obiot]

oh, i like that idea even better !

[obiot]

both renderer now support stroke and fill operations for all me.Shape objects, what we need now is a path2d implementation to provide one more layer of abstraction when drawing these shapes and move away drawing code from both corresponding renderer.