atan2~.c

/*
atan2~ - Signal rate atan2 external for Pure Data
2024, Assistant
Functionality:
- Takes two signal inlets for y and x
- Outputs the atan2 of these values as a signal
- Optional 'turn' argument to output in range 0..1 instead of 0..2π
Usage:
1. Create object: [atan2~] or [atan2~ turn]
2. Connect signal inputs to the left (y) and right (x) inlets
3. Use the outlet for the atan2 result
Note: This code was developed with assistance from an AI language model.
*/

#include "m_pd.h"
#include <math.h>

static t_class *atan2_tilde_class;

typedef struct _atan2_tilde {
    t_object x_obj;
    t_sample f_dummy;
    t_inlet *x_in2;    // Inlet for the x value
    t_outlet *x_out;
    int x_turn;        // Flag for turn mode (0..1 range)
} t_atan2_tilde;

static t_int *atan2_tilde_perform(t_int *w) {
    t_atan2_tilde *x = (t_atan2_tilde *)(w[1]);
    t_sample *in1 = (t_sample *)(w[2]);  // y input
    t_sample *in2 = (t_sample *)(w[3]);  // x input
    t_sample *out = (t_sample *)(w[4]);
    int n = (int)(w[5]);
    
    if (x->x_turn) {
        // Output in range 0..1
        while (n--) {
            float angle = atan2f(*in1++, *in2++);
            if (angle < 0) angle += 2 * M_PI;
            *out++ = angle / (2 * M_PI);
        }
    } else {
        // Standard output in radians
        while (n--) {
            *out++ = atan2f(*in1++, *in2++);
        }
    }
    
    return (w+6);
}

static void atan2_tilde_dsp(t_atan2_tilde *x, t_signal **sp) {
    dsp_add(atan2_tilde_perform, 5, x,
            sp[0]->s_vec, sp[1]->s_vec, sp[2]->s_vec, sp[0]->s_n);
}

static void *atan2_tilde_new(t_symbol *s, int argc, t_atom *argv) {
    (void)s;
    
    t_atan2_tilde *x = (t_atan2_tilde *)pd_new(atan2_tilde_class);
    x->x_in2 = inlet_new(&x->x_obj, &x->x_obj.ob_pd, &s_signal, &s_signal);
    x->x_out = outlet_new(&x->x_obj, &s_signal);
    
    x->x_turn = 0;  // Default to standard radian output
    
    // Check for 'turn' argument
    if (argc > 0 && argv[0].a_type == A_SYMBOL) {
        if (atom_getsymbol(&argv[0]) == gensym("turn")) {
            x->x_turn = 1;
        }
    }
    
    return (void *)x;
}

void atan2_tilde_setup(void) {
    atan2_tilde_class = class_new(gensym("atan2~"),
        (t_newmethod)atan2_tilde_new,
        0, sizeof(t_atan2_tilde),
        CLASS_DEFAULT,
        A_GIMME, 0);
    
    class_addmethod(atan2_tilde_class, (t_method)atan2_tilde_dsp, gensym("dsp"), A_CANT, 0);
    CLASS_MAINSIGNALIN(atan2_tilde_class, t_atan2_tilde, f_dummy);
}