Bgcolor with transparent alpha value has strange behavior

[grant-wilson]

Pts behaves strangely when the bgcolor is transparent. The canvas slowly darkens and visual artifacts appear.
This can be demonstrated with this simple demo.
pts_demo.zip

[williamngan]

Hi @grant-wilson -- you can use "transparent" or false to set the bgcolor instead of an rgba value. Eg:

space.setup( {bgcolor: "transparent"} );

Alternatively, you can clear the canvas by calling space.clear("transparent") when needed.

I just realize the CanvasSpace's setup documentation was truncated so the parameters were hidden. I will fix it asap.

Thanks!

[grant-wilson]

Hi @williamngan ,

Thank you for the quick reply.
You are right that using the color name "transparent" works great!
This is exactly what I needed.

However I would argue that the behavior seen when using an rgba value with an alpha less than ff is probably not intended.
You can see what happens by running the pts_demo.html file I attached.

I have updated the title to reflect more clearly what I am talking about.

[williamngan]

Thanks @grant-wilson. I see what you mean now -- that's a good catch. I will try to fix it in the next release.

In the meantime, you can call space.clear( "transparent" ) and then draw a semi-transparent rect that fills the canvas as a temporary fix.

[jperrett256]

Not sure if should be separate issue, but it falls under same heading, so I thought it was worth mentioning here.
While "transparent" does work, using false for bgcolor does not seem to work. (Contradicts the documentation.)
pts_demo.zip

[williamngan]

Thanks for report this @jperrett256 -- this looks like a regression and we will fix it in the next patch release!

[williamngan]

@jperrett256 - this should be fixed in v0.10.4. Thanks again for reporting the issue.

[williamngan]

Closing this issue now. Please reopen if there're still issues.