We can use XY slider objects as graphical representation of activity (state changes) on assigned audio process parameters. The XY slider can be activated with mouse point click-drag or any gesture control device such as joystick or sensors (via MCU and serial communication protocol) to output XY data.
Alternatively, you can create ‘similar’ XY slider (primitive) above in Pure Data using layer of [array] and [Hslider] object. Only mouse point steady-click is working for the [array] object as opposed to Hslider ‘jump on click’ setting. Therefore, you need to click your mouse over the array-hslider to input the XY data. However, you can use serial/MIDI data for continuous Y data feed to emulate the ‘drag’ motion.
Quick solution for drag option with mouse; you may use [else/slider2d] object via ELSE external library for PD and explore the process behind it. Note that complex graphical object may affect your PD CPU load and performance (latency).
Another ‘long-learning-route’ option is to explore using [mousestate] object from cyclone library. You may want to explore this if you want to design complex GUI sonic motion-event gate/trigger such as spatial audio controller.