nih-plug/plugins/examples/gain/src/lib.rs

#[macro_use]
extern crate nih_plug;

use nih_plug::{
    formatters, util, Buffer, BufferConfig, BusConfig, Plugin, ProcessContext, ProcessStatus,
    Vst3Plugin,
};
use nih_plug::{BoolParam, FloatParam, Params, Range, Smoother, SmoothingStyle};
use parking_lot::RwLock;
use std::pin::Pin;
use std::sync::Arc;

struct Gain {
    params: Pin<Box<GainParams>>,
}

#[derive(Params)]
struct GainParams {
    #[id = "gain"]
    pub gain: FloatParam,

    #[id = "as_long_as_this_name_stays_constant"]
    pub the_field_name_can_change: BoolParam,

    /// This field isn't used in this exampleq, but anything written to the vector would be restored
    /// together with a preset/state file saved for this plugin. This can be useful for storign
    /// things like sample data.
    #[persist = "industry_secrets"]
    pub random_data: RwLock<Vec<f32>>,
}

impl Default for Gain {
    fn default() -> Self {
        Self {
            params: Box::pin(GainParams::default()),
        }
    }
}

impl Default for GainParams {
    fn default() -> Self {
        Self {
            // There are three ways to specify parameters:
            //
            // ...either manually specify all fields:
            gain: FloatParam {
                value: 0.0,
                smoothed: Smoother::new(SmoothingStyle::Linear(50.0)),
                value_changed: None,
                range: Range::Linear {
                    min: -30.0,
                    max: 30.0,
                },
                name: "Gain",
                unit: " dB",
                value_to_string: Some(formatters::f32_rounded(2)),
                string_to_value: None,
                // ...or specify the fields you want to initialize directly and leave the other
                // fields at their defaults:
                // // ..Default::default(),
            },
            // ...or use the builder interface:
            the_field_name_can_change: BoolParam::new("Important value", false).with_callback(
                Arc::new(|_new_value: bool| {
                    // If, for instance, updating this parameter would require other parts of the
                    // plugin's internal state to be updated other values to also be updated, then
                    // you can use this callback to for instance modify an atomic in the plugin.
                }),
            ),
            // Persisted fields can be intialized like any other fields, and they'll keep their when
            // restoring the plugin's state.
            random_data: RwLock::new(Vec::new()),
        }
    }
}

impl Plugin for Gain {
    const NAME: &'static str = "Gain";
    const VENDOR: &'static str = "Moist Plugins GmbH";
    const URL: &'static str = "https://youtu.be/dQw4w9WgXcQ";
    const EMAIL: &'static str = "info@example.com";

    const VERSION: &'static str = "0.0.1";

    const DEFAULT_NUM_INPUTS: u32 = 2;
    const DEFAULT_NUM_OUTPUTS: u32 = 2;

    const ACCEPTS_MIDI: bool = false;

    fn params(&self) -> Pin<&dyn Params> {
        self.params.as_ref()
    }

    fn accepts_bus_config(&self, config: &BusConfig) -> bool {
        // This works with any symmetrical IO layout
        config.num_input_channels == config.num_output_channels && config.num_input_channels > 0
    }

    fn initialize(
        &mut self,
        _bus_config: &BusConfig,
        _buffer_config: &BufferConfig,
        _context: &mut impl ProcessContext,
    ) -> bool {
        // This plugin doesn't need any special initialization, but if you need to do anything
        // expensive then this would be the place. State is kept around while when the host
        // reconfigures the plugin.
        true
    }

    fn process(
        &mut self,
        buffer: &mut Buffer,
        _context: &mut impl ProcessContext,
    ) -> ProcessStatus {
        for samples in buffer.iter_mut() {
            // Smoothing is optionally built into the parameters themselves
            let gain = self.params.gain.smoothed.next();

            for sample in samples {
                *sample *= util::db_to_gain(gain);
            }
        }

        ProcessStatus::Normal
    }
}

impl Vst3Plugin for Gain {
    const VST3_CLASS_ID: [u8; 16] = *b"GainMoistestPlug";
    const VST3_CATEGORIES: &'static str = "Fx|Dynamics";
}

nih_export_vst3!(Gain);