Changing Current Preset for RNBO patch

tmarasco125

Hi there!

I'm working on a project using RNBO and Bela. The RNBO patch I'm exporting to C++ has presets established, and I read on the Getting Started post [https://learn.bela.io/using-bela/languages/rnbo/#loading-presets](https://) that the first present included in the present.json file will be auto loaded on start up.

I'd like to hook up a button to my Bela and use button presses to cycle through and load the presets available in my JSON file. However, I'm unsure what function to call when assigning my digital input in the render.cpp file to tie the button press to this behavior. Can someone point me in the right direction for getting this set-up?

giuliomoro

In https://github.com/giuliomoro/rnbo.example.bela/blob/dev/render.cpp the first preset is loaded in setup() at these lines:

		if(presetList->size())
		{
			unsigned int idx = 0;
			RNBO::UniquePresetPtr preset = presetList->presetAtIndex(idx);
			printf("Loading preset %d: %s\n", idx, presetList->presetNameAtIndex(idx).c_str());
			rnbo->setPreset(std::move(preset));
		}

what you would need is something in render.cpp that from within render() does the following:

checks for a button press
increments a counter of the current preset
loads the next preset

E.g. something like this might work:

void render(BelaContext *context, void *userData)
{
...
    const int kPresetBtn = 10; // digital in 10
    static bool pastPresetBtnRead = false; // button reads low when not pressed and high when pressed
    bool presetRead = digitalRead(context, 0, kPresetBtn);
    // checks for a button press
    if(presetRead && presetRead != pastPresetBtnRead)
    {
         // button press just started: load next preset
        if(presetList->size())
        {
            static unsigned int currentPreset = 0; 
            currentPreset++;
            if(currentPreset >= presetList->size())
               currentPreset = 0;
            RNBO::UniquePresetPtr preset = presetList->presetAtIndex(currentPreset);
            printf("Loading preset %d: %s\n", currentPreset, presetList->presetNameAtIndex(currentPreset).c_str());
            rnbo->setPreset(std::move(preset));
        }
    }
...
}