On Wed, Mar 13, 2013 at 9:49 PM, Gregg Tavares <[email protected]> wrote:
> On Wed, Mar 13, 2013 at 9:20 PM, Maciej Stachowiak <[email protected]> wrote: > >> >> Two questions/comments: >> >> 1) What happens if I do: >> gl = canvas.getContext("experimental-webgl", { alpha: false }); >> and then later, in an unrelated piece of code I do the following on the >> same canvas: >> gl = canvas.getContext("experimental-webgl"); >> >> Will the canvas remain opaque? Will the buffer be wiped? Will it turn >> non-opaque without wiping the buffer? Based on my guesses of the answers to >> these questions, I feel like this approach is dangerous because you have to >> remember to pass the right parameters each time you retrieve the context. >> But really you should be able to set it once and then retrieve the context >> an arbitrary number of times without repeating yourself. >> > > The parameters are ignored the second time. The spec already says you get > the same context that was create the first time you called getContext. > That sounds horribly confusing. Can we please change this API? 2) I think alpha: false is a particularly bad name for the reasons Elliott >> stated - it sounds like it would disable all alpha compositing for all >> drawing operations done within the canvas, whereas what it actually does is >> force the composited results of canvas drawing to have alpha of 1.0. Is >> WebGL locked into the "alpha: false" syntax? >> > > "alpha: false" means there is no alpha channel, effectively making it 1.0. > You can't write to it. If you try to read it (readPixels, getImageData) all > the alpha data will be 255. It says nothing about compositing. But, the > fact that the UA knows this guarantees there is either no alpha or that > alpha is 1.0 through the entire surface means that UA and choose to render > without blending when appropriate. > I agree with others that this is a very misleading name. I get the sentiment of it but it's a bad name nonetheless. - R. Niwa
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