To update a part of the attributes, you have an array with a fitting size. In your example, you are trying to stuff an array with the size of 420 into VAs with the size of 420, starting at index 6. It doesn't work that way. Your array should be 414 in size and the data has to start at index 0, not 6 in that array.
Does it mean 'start' parameter always has to be zero?
'start' parameter is the index for updatedData right?
With same vertex attribute data above (length 420), I've tried:
float[] updatedData = { 1, 2, 3, 4 };
attribs.update(updatedData, 1);
with same Exception, Invalid size: 1/4.
Now, I'm just curious why it doesn't work when 'start' parameter has a value larger than zero.
And,
when I update VertexAttributes data, the order of the vertex is often change between each run.
Is this the expected behaviour when vertex sharing is enabled?
Thanks.