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add custom octave scaling, more efficient persistence handling
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@ben-wes
ben-wes committed May 7, 2024
1 parent 00c005e commit 3f15acd
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72 changes: 37 additions & 35 deletions simplex~-help.pd
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#N struct 1082-path-template float x float y array 1082-data 1082-data-template;
#N struct 1082-data-template float x float y;
#N struct 1085-path-template float x float y array 1085-data 1085-data-template;
#N struct 1085-data-template float x float y;
#N struct 1086-path-template float x float y array 1086-data 1086-data-template;
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#N struct 1087-path-template float x float y array 1087-data 1087-data-template;
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#N struct 1014-data-template float x float y;
#N canvas 366 153 1104 831 10;
#N canvas 200 100 298 221 (subpatch) 0;
#X obj 50 70 inlet~;
Expand Down Expand Up @@ -133,7 +133,6 @@
#X text 834 237 <-- activate to see visualizations below;
#X obj 599 738 output~;
#X msg 890 146 seed;
#X text 379 83 single numerical argument sets octave count (default: 1);
#X text 402 104 additional numerical argument sets persistence (default: 0.5), f 61;
#X msg 890 125 normalize 0;
#X text 967 125 on/off;
Expand Down Expand Up @@ -204,6 +203,9 @@
#X text 449 695 circular scan \, slowly moving upwards (i.e. spiral movement) \, resulting in a periodic waveform. sampled values displace y-position., f 22;
#X text 611 695 the periodic signal based on the spiral movement., f 23;
#X text 806 695 scanning a spherical shape \, moving in 4th dimension (w-coord). sampled values displace radius., f 23;
#X text 890 167 <-- custom octave scale factors;
#X msg 809 167 coeffs 1 3 5;
#X text 379 83 single numerical argument sets octave count (default: 1 \, max: 24), f 65;
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51 changes: 43 additions & 8 deletions simplex~.c
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Expand Up @@ -9,6 +9,7 @@

#define PERSISTENCE 0.5f
#define MAX_DIMENSIONS 4
#define MAX_OCTAVES 24

#define F2 0.36602540378f // 0.5*(sqrt(3.0)-1.0);

Expand All @@ -33,6 +34,7 @@ typedef struct _simplex_tilde {
t_inlet *inlet_persistence;
int normalize;
int octaves;
t_float octave_factors[MAX_OCTAVES];
int perm[512];
} t_simplex_tilde;

Expand Down Expand Up @@ -388,19 +390,33 @@ static t_float snoise4(t_simplex_tilde *x, t_float x_in, t_float y_in, t_float z
}

static inline t_float generate_noise(t_simplex_tilde *x, t_float *pos, t_float persistence, int channel_count) {
t_float result = 0.0, persistence_sum = 0.0, scale, coeff;
t_float result = 0.0f;
t_float coeff = 1.0f;
t_float normalize_factor = 1.0f;
t_float scale;

// normalization according to inversed geometric series including a^0 based
// on given persistence:
//
// a - 1
// s = -------
// a^n - 1
//
if (x->normalize) {
normalize_factor = persistence - 1.0f;
normalize_factor /= pow(persistence, x->octaves) - 1.0f;
}
static t_float (*noise_func[])(t_simplex_tilde *, t_float, t_float, t_float, t_float) = {
snoise1, snoise2, snoise3, snoise4
};

for (int octave = 0; octave < x->octaves; octave++) {
scale = pow(2, octave);
coeff = pow(persistence, octave);
persistence_sum += fabs(coeff);
if (octave > 0)
coeff *= persistence;
scale = x->octave_factors[octave];
result += noise_func[channel_count-1](x, pos[0] * scale, pos[1] * scale, pos[2] * scale, pos[3] * scale) * coeff;
}

return x->normalize ? result / persistence_sum : result;
return result * normalize_factor;
}

static t_int *simplex_tilde_perform(t_int *w) {
Expand All @@ -426,8 +442,14 @@ void simplex_tilde_dsp(t_simplex_tilde *x, t_signal **sp) {
dsp_add(simplex_tilde_perform, 6, x, (t_int)sp[0]->s_n, (t_int)sp[0]->s_nchans, sp[0]->s_vec, sp[1]->s_vec, sp[2]->s_vec);
}

static inline void init_octave_factors(t_simplex_tilde *x){
for (int octave = 0; octave < x->octaves; octave++)
x->octave_factors[octave] = (t_float)(1 << octave);
}

static void simplex_tilde_octaves(t_simplex_tilde *x, t_floatarg f){
x->octaves = fastfloor(f);
x->octaves = fastfloor(min(MAX_OCTAVES, f));
init_octave_factors(x);
}

static void simplex_tilde_normalize(t_simplex_tilde *x, t_floatarg f){
Expand All @@ -446,6 +468,16 @@ static void simplex_tilde_seed(t_simplex_tilde *x, t_symbol *s, int ac, t_atom *
(void)s;
}

static void simplex_tilde_coeffs(t_simplex_tilde *x, t_symbol *s, int ac, t_atom *av) {
int i;
x->octaves = min(MAX_OCTAVES, ac);
for (i = 0; i < x->octaves; i++){
x->octave_factors[i] = atom_getfloat(av);
av++;
}
(void)s;
}

static void simplex_tilde_free(t_simplex_tilde *x){
inlet_free(x->inlet_persistence);
}
Expand All @@ -466,8 +498,10 @@ static void *simplex_tilde_new(t_symbol *s, int ac, t_atom *av) {
pd_error(x, "[simplex~]: invalid argument");
ac--, av++;
}
x->octaves = ac-- ? atom_getint(av++) : 1;
x->octaves = ac-- ? min(MAX_OCTAVES, atom_getint(av++)) : 1;
persistence = ac>0 ? atom_getfloat(av) : PERSISTENCE;
init_octave_factors(x);

x->inlet_persistence = inlet_new(&x->x_obj, &x->x_obj.ob_pd, &s_signal, &s_signal);
pd_float((t_pd *)x->inlet_persistence, persistence);
outlet_new(&x->x_obj, &s_signal);
Expand All @@ -484,6 +518,7 @@ void simplex_tilde_setup(void) {
class_addmethod(simplex_tilde_class, nullfn, gensym("signal"), 0);
class_addmethod(simplex_tilde_class, (t_method)simplex_tilde_dsp, gensym("dsp"), 0);
class_addmethod(simplex_tilde_class, (t_method)simplex_tilde_seed, gensym("seed"), A_GIMME, 0);
class_addmethod(simplex_tilde_class, (t_method)simplex_tilde_coeffs, gensym("coeffs"), A_GIMME, 0);
class_addmethod(simplex_tilde_class, (t_method)simplex_tilde_octaves, gensym("octaves"), A_FLOAT, 0);
class_addmethod(simplex_tilde_class, (t_method)simplex_tilde_normalize, gensym("normalize"), A_FLOAT, 0);
class_addmethod(simplex_tilde_class, (t_method)simplex_tilde_persistence, gensym("persistence"), A_FLOAT, 0);
Expand Down

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