Channels effect crashes when setting alphaSource when source is undefined

[positlabs]

I tried making an alpha mask for a webcam feed, but it's failing if I assign alphaSource immediately after instantiating the channels effect.

            var img = document.createElement('img');
            img.src = 'assets/imgs/alphamask-test.png';

            var cameraMask = seriously.effect('channels');
            cameraMask.alphaSource = seriously.source(img); // fails!

But if I wait a tick, it works just fine.

            setTimeout(function(){
                cameraMask.alphaSource = seriously.source(img); // succeeds!
            }, 1);

Seems like it's probably a simple thing to fix, but for now I'll use this workaround.

Here's some screenshots, in case they help.

[positlabs]

Seems like there is also a problem when setting cameraMask.source a second time. I get this error: Uncaught TypeError: Cannot read property 'useProgram' of undefined

[positlabs]

Maybe not the best approach, but checking for undefined source before adding it to the array works. It fixes the issue of having to delay assigning source, but not the issue of reassigning source.

        function validateSource(name) {
            ...
            if (j < 0 && s !== undefined) {
                ...
            }
        }

[brianchirls]

Thanks for reporting. I'm making some progress on this. Can you share some sample code or a stacktrace for the reassigning source problem?

[brianchirls]

Looks like the reason your workaround works is that somewhere after the setTimeout, you set a source or another channel on that node. So it's not really about waiting a tick - it's just about setting alphaSource after another input. Is that right?

[positlabs]

I'll work on making a test case.

Yep, assigning source before alphaSource does the trick!

Here are some shots of what happens when I try switching source after it's been assigned once.

[positlabs]

Here's a test case.

https://drive.google.com/file/d/0BxHpmZYCB3c2WXhTYXdmUGN1SUk/view?usp=sharing