instrument: try to simulate violin

But apparently it still sounds very bad.

1 files changed, 58 insertions, 43 deletions

diff --git a/instrument.c b/instrument.c
index edb2f76..097ede4 100644
--- a/instrument.c
+++ b/instrument.c
@@ -179,21 +179,37 @@ UH_ATTR
 Pulse
 violin_sound_internal(Instrument *in, float theta)
 {
-  /* return -1.0f*fmod(theta, 2.0f*M_PI)/M_PI + 1.0f; */
+  return -1.0f*fmod(theta, 2.0f*M_PI)/M_PI + 1.0f;
   /* return (*(in->sin_coefs)*sin(theta)+
    *         *(in->sin_coefs+1)*sin(2.0f*theta)+
    *         *(in->sin_coefs+2)*sin(3.0f*theta)+
    *         *(in->sin_coefs+3)*sin(4.0f*theta)+
    *         *(in->sin_coefs+4)*sin(5.0f*theta)); */
-  Pulse result = 0.0f;
-  for (int i = 0; i < 26; i++)
-    result += *(in->sin_coefs+i) * sin((float) (i+1)*theta);
+  /* Pulse result = 0.0f;
+   * for (int i = 0; i < 4; i++)
+   *   result += *(in->sin_coefs+i) * sin((float) (i+1)*theta); */
   /* result = sin(theta); */
   
-  return result;
+  /* return result; */
 }
 
 UH_ATTR
+float violin_adsr(Instrument *violin, float t)
+{
+  if (t <= 0.0f || t > 1.0f)
+    return 0.0f;
+  
+  if (t <= violin->adsr.attack_p)
+    return log(1.0f + 2.7f*(t / violin->adsr.attack_p));
+  else if (t <= violin->adsr.decay_p+violin->adsr.attack_p)
+    return (t - violin->adsr.attack_p) / violin->adsr.decay_p;
+  else if (t <= 1.0f - violin->adsr.release_p)
+    return violin->adsr.sustain_level;
+  else
+    return 1.0f - (1.0f - t) / violin->adsr.release_p;
+}
+  
+UH_ATTR
 WaveFrag
 violin_sound(void * in, Volume v, Hertz h, Seconds s)
 {
@@ -205,52 +221,51 @@ violin_sound(void * in, Volume v, Hertz h, Seconds s)
   
   float step = (float) (h * 2 * M_PI) / SAMPLE_RATE;
   LENT sample_num = (LENT) floor(SAMPLE_RATE * s);
-  float attack_step = 1.0f / (float) (sample_num * violin->adsr.attack_p);
-  float decay_step = 1.0f / (float) (sample_num * violin->adsr.decay_p);
-  float sustain_step = 1.0f / (float) (sample_num * violin->adsr.sustain_p);
-  float release_step = 1.0f / (float) (sample_num * violin->adsr.release_p);
+  /* float attack_step = 1.0f / (float) (sample_num * violin->adsr.attack_p);
+   * float decay_step = 1.0f / (float) (sample_num * violin->adsr.decay_p);
+   * float sustain_step = 1.0f / (float) (sample_num * violin->adsr.sustain_p);
+   * float release_step = 1.0f / (float) (sample_num * violin->adsr.release_p); */
 
   Wave w = MYALLOC(Pulse, sizeof(*w) * sample_num);
   
   float theta = 0.0f, temp = 0.0f, adsrcounter = 0.0f;
 
-  unsigned char phase = 0, sustain_flag = 0;
-  
   for (LENT i = 0; i < sample_num; i++, theta += step) {
     temp = violin_sound_internal(violin, theta);
+    adsrcounter = violin_adsr(violin, (float) i / sample_num);
     /* temp += temp*temp*temp; */
     /* *(w+i) = (float) v * temp * ((sustain_flag) ? SUSTAIN_LEVEL : adsrcounter); */
-    *(w+i) = (float) v * temp;
+    *(w+i) = (float) v * temp * adsrcounter;
     
-    switch (phase) {
-    case 0:                     /* attack phase */
-      adsrcounter += attack_step;
-      if (adsrcounter >= 1.0f) {
-        adsrcounter = 1.0f;
-        phase++;
-      }
-      break;
-    case 1:                     /* decay phase */
-      adsrcounter -= decay_step;
-      if (adsrcounter <= SUSTAIN_LEVEL) {
-        adsrcounter = 0.0f;
-        sustain_flag = 1;
-        phase++;
-      }
-      break;
-    case 2:                     /* sustain phase */
-      adsrcounter += sustain_step;
-      if (adsrcounter >= 1.0f) {
-        adsrcounter = SUSTAIN_LEVEL;
-        sustain_flag = 0;
-        phase++;
-      }
-      break;
-    default:                    /* release phase */
-      adsrcounter -= release_step;
-      if (adsrcounter <= 0.0f) adsrcounter = 0.0f;
-      break;
-    }
+    /* switch (phase) {
+     * case 0:                     /\* attack phase *\/
+     *   adsrcounter += attack_step;
+     *   if (adsrcounter >= 1.0f) {
+     *     adsrcounter = 1.0f;
+     *     phase++;
+     *   }
+     *   break;
+     * case 1:                     /\* decay phase *\/
+     *   adsrcounter -= decay_step;
+     *   if (adsrcounter <= SUSTAIN_LEVEL) {
+     *     adsrcounter = 0.0f;
+     *     sustain_flag = 1;
+     *     phase++;
+     *   }
+     *   break;
+     * case 2:                     /\* sustain phase *\/
+     *   adsrcounter += sustain_step;
+     *   if (adsrcounter >= 1.0f) {
+     *     adsrcounter = SUSTAIN_LEVEL;
+     *     sustain_flag = 0;
+     *     phase++;
+     *   }
+     *   break;
+     * default:                    /\* release phase *\/
+     *   adsrcounter -= release_step;
+     *   if (adsrcounter <= 0.0f) adsrcounter = 0.0f;
+     *   break;
+     * } */
   }
 
   return (WaveFrag) { w, sample_num };
@@ -341,8 +356,8 @@ make_violin()
   violin->adsr.pred = 1;
   
   violin->reverb = 0.01f;
-  violin->adsr.attack_p = 0.55;
-  violin->adsr.release_p = 0.25;
+  violin->adsr.attack_p = 0.09;
+  violin->adsr.release_p = 0.09;
   violin->adsr.decay_p = 0.05;
   violin->adsr.sustain_p = max(1.0f - (violin->adsr.attack_p+
                                        violin->adsr.decay_p+