[Public WebGL] using the same context with multiple canvases

Tony Parisi [email protected]
Wed Dec 12 08:13:43 PST 2012

Long thread...

I just wanted to throw my opinion in to mirror Ian's, that if we go down
this path, it should work for 2d canvas drawing contexts as well. a) seems
just as useful for 2D drawing and b) I would think that consistency with
the other canvas context behavior would be highly desirable.


On Wed, Dec 12, 2012 at 8:00 AM, Florian Bösch <[email protected]> wrote:

> On Wed, Dec 12, 2012 at 4:45 PM, Vladimir Vukicevic <[email protected]>wrote:
>> does that getContext conceptually create a Drawingbuffer and call
>> setDrawingbuffer on the canvas, as well as call bindDrawingbuffer on the gl
>> context?
> Yes
>> Is Drawingbuffer webgl-specific, or a general abstraction? (Bikeshed
>> note: we need a better name than "Drawingbuffer" IMO...). However, we'd
>> still need to determine the types of contexts that it can be used with if
>> it's general.  Maybe something like:
> We've iterated this already on this thread in October, Frontbuffer was
> worse, framebuffer is easily confused with framebuffer object,
> drawingbuffer is actually a pretty good description.
>> gl = new WebGLRenderingContext();
>> db1 = gl.createDrawingBuffer({ depth: false });
>> canvas.displayDrawingBuffer(**db1);  // setDrawingBuffer on the canvas
>> seems like a weird API name, as we're really choosing what buffer to
>> display; what buffer is drawn to is selected by the context
> How about canvas.setDisplayBuffer(db1) ?
>> twodee = Canvas2DRenderingContext();
>> db2 = twodee.createDrawingBuffer({ doubleBuffer: true });
>> canvas.displayDrawingBuffer(**db2);  // is this legal; canvas originally
>> displayed a webgl buffer?
> It should be legal in my opinion to attach an entirely different drawing
> buffer to the same canvas. The context specificity goes with the drawing
> buffer.
>> db1 = new Drawingbuffer("webgl", { depth: false });
>> db2 = new Drawingbuffer("2d", { doubleBuffer: true });
> It's an interesting question, I might be wrong but people where arguing
> for a context independent way to create drawing buffers (somewhere back in
> october?).

Tony Parisi                             [email protected]
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