A simple example of a custom shader in a Flutter app.
The shader under shaders/example.frag computes a color for each pixel
that depends only on the position and the "time". The time is supplied as
a uniform to the shader, and so we can use a CustomPainter to animate it.
This example uses the API as found in the 3.3 stable release of Flutter.
After this PR lands, the API
will be different. Please see the TODO comments in the source code for details
of what the migration looks like.
To run on platforms other than macOS, first run the appropriate
flutter create command to generate their platform specific files.