Changeable Arguments & Attributes
Hello all,
This is a dumb question that I should know by now, but how do I make argument or attribute values accessible from outside an object so that they can be changed dynamically with values from elsewhere in the patch? In other words, if there's a number value or symbol that can't remain static, but must change while operating the patch, how can they be changed with a separate input on that object or by using a message object?
For example, if there is an application where I have a buffer~ object, but I need to change the number of channels, @filetype, and @samps on the fly without editing the object each time, how can this be done?
In the attached image, I'm trying to use the face bounds being generated from the cv.jit.faces object to manipulate the viewport of a jit.gl.camera object. How can this be done?
[pak attribute f i I etc] or attribute $
works in [p window]
where attrui does not
in many cases set without triggering
use [pack ] instead of [pak ]
In a more general way, to change an objects attribute, you need to send to the object a message starting with the attribute name followed by the new value. When you have only the value and just need to add the attributes name, [prepend] can help too.
In your case, if you want to control the vieport of jit.gl.camera using the matrix output from [cv.jit.faces], you'll need a few extra steps:
Convert the rectangles coordinates from pixel number (going from 0 to dim-1) to normalized values (going from 0. to 1.)
Convert the data type from matrix to list (you can use [jit.iter] for that)
You can perform the first step either in the matrix domain using [jit.gen] or [jit.expr], or in the list domain using [vexpr].
Here's an example using jit.gen
Thanks, this all helps a lot.
The other question is the use of $ and # for changing arguments and attributes. I think I've seen them used for that purpose before. Using $ to create inputs for the expr object for example, ie. "expr $f1 + $f2", is pretty straightforward, but I think I've seen them for more varied/complex applications. I've read the documents page for arguments, but still don't completely understand the syntax for this. Do they go inside the object with the attributes or arguments you want to manipulate, as in the case of the expr object, or do they always go in a message before the object with a prepend object to indicate what parameter is being manipulated? If you could describe how $ and # is used and/or some common use cases for this, that would help a lot.